Biology subjects

Zeng, L.

Publications and source records attributed to Zeng, L..

At least 55 records · Page 3Linked to original sources

bioRxiv2024

Integrated Dual-Channel Retrograde Signaling Directs Stress Responses by Degrading the HAT1/TPL/IMPalpha-9 Suppressor Complex and Activating CAMTA3

The intricate communication between plastids and the nucleus, shaping stress-responsive gene expression, has long intrigued researchers. This study combines genetics, biochemical analysis, cellular biology, and protein modeling to uncover how the plastidial metabolite MEcPP activates the stress-response regulatory hub known as the Rapid Stress Response Element (RSRE). Specifically, we identify the HAT1/TPL/IMP- 9 suppressor complex, where HAT1 directly binds to RSRE and its activator, CAMTA3, masking RSRE and sequestering the activator. Stress-induced MEcPP disrupts this complex, exposing RSRE and releasing CAMTA3, while enhancing Ca2+ influx and raising nuclear Ca2+levels crucial for CAMTA3 activation and the initiation of RSRE- containing gene transcription. This coordinated breakdown of the suppressor complex and activation of the activator highlights the dual-channel role of MEcPP in plastid-to- nucleus signaling. It further signifies how this metabolite transcends its expected biochemical role, emerging as a crucial initiator of harmonious signaling cascades essential for maintaining cellular homeostasis under stress. SummaryThis study uncovers how the stress-induced signaling metabolite MEcPP disrupts the HAT1/TPL/IMP-9 suppressor complex, liberating the activator CAMTA3 and enabling Ca2+ influx essential for CAMTA3 activation, thus orchestrating stress responses via repressor degradation and activator induction.

plant biology↗

bioRxiv2024

Berberine is a novel mitochondrial calcium uniporter (MCU) inhibitor that disrupts MCU-EMRE assembly

The mitochondrial calcium uniporter (MCU) complex mediates Ca2+ entry into mitochondrial, which plays a crucial role in regulating cellular energy metabolism and apoptosis. Dysregulation of MCU is implicated in various diseases, such as neurodegenerative disorders, cardiac diseases and cancer. Despite its importance, developing specific and clinically viable MCU inhibitors has been challenging. Here, we identify Berberine, a well-established drug with a documented safety profile, as a potent MCU inhibitor through a virtual screening of an FDA-approved drug library. Berberine localizes within mitochondria and directly binds to the juxtamembrane loop domain of MCU. This binding disrupts the interaction of MCU with its essential regulator, EMRE, thereby inhibiting rapid Ca2+ entry into the mitochondria. Notably, Berberine pretreatment reduces mitochondrial Ca2+ overload and mitigate ischemia/reperfusion-induced myocardial injury in mice. Our findings establish Berberine as a potent MCU inhibitor, offering a safe therapeutic strategy for diseases associated with dysregulated mitochondrial calcium homeostasis.

cell biology↗

bioRxiv2024

Systematic Analysis of the Glucose-PTS in Streptococcus sanguinis Highlighted its Importance in Central Metabolism and Bacterial Fitness

Previous work reported that deletion of the Enzyme IIAB subunits (EIIABMan, manL) of the glucose phosphotransferase system (glucose-PTS, manLMNO) in Streptococcus sanguinis impacted carbon catabolite repression (CCR) and bacterial fitness. Here, a single nucleotide polymorphism in ManN, ManNA91E, produced the unusual phenotype of increased excretion of organic acids and H2O2, yet elevated PTS activities. To characterize the contributions of each component of the glucose-PTS to bacterial fitness, we performed genetic analyses by deleting from S. sanguinis SK36 the entire operon and each EIIMan subunit individually; and genes encoding the catabolite control protein CcpA ({Delta}ccpA) and the redox regulator Rex ({Delta}rex) for comparison. Deletion of each subunit incurred a growth defect on glucose partly due to elevated excretion of H2O2; when supplemented with catalase this defect was rescued, instead resulting in a significantly higher yield than the parent. All glucose-PTS deletion mutants presented an increased antagonism against the oral pathobiont Streptococcus mutans, a phenotype absent in {Delta}ccpA despite increased H2O2 output. A shift in the pyruvate node towards mixed acid fermentation and increased arginine deiminase activity enhanced pH homeostasis in glucose-PTS mutants, but not {Delta}ccpA. Despite the purported ability of Rex to regulate central carbon metabolism, deletion of rex had no significant impact on most of the phenotypes discussed here. These findings place glucose-PTS in the pivotal position of controlling central carbon flux in streptococci, with critical outcomes impacting acidogenicity, aciduricity, pH homeostasis, and antagonism, highlighting its potential as a therapeutic target for treating diseases with a dysbiotic microbiome. ImportanceManagement of carbohydrate metabolism and environmental stress is key to the survival of oral commensal species such as S. sanguinis. Antagonism of oral pathobionts and modulation of the environmental pH and oxidative potential by commensals are crucial to the maintenance of microbial homeostasis and prevention of oral diseases including dental caries. It is therefore vital to understand how these species regulate sugar fermentation, production of acids and ammonia, and stress management in an environment known for a feast-and-famine cycle of carbohydrates and similar fluctuations in pH and oxygen tension. Here, we detail that genetic alterations of the glucose-PTS transporter in S. sanguinis can significantly affect the regulation of factors required for bacterial fitness and homeostatic ability independent of known catabolic regulators, it is then discussed how these changes may impact the survival of streptococcal species and affect caries onset.

microbiology↗

bioRxiv2024

Glycerol Metabolism Contributes to Competition by Oral Streptococci through Production of Hydrogen Peroxide

As a biological byproduct from both humans and microbes, glycerols contribution to microbial homeostasis in the oral cavity remains understudied. Here we examined glycerol metabolism by Streptococcus sanguinis, a commensal associated with oral health. Genetic mutants of glucose-PTS enzyme II (manL), glycerol metabolism (glp and dha pathways), and transcriptional regulators were characterized with regard to glycerol catabolism, growth, production of hydrogen peroxide (H2O2), transcription, and competition with Streptococcus mutans. Biochemical assays identified the glp pathway as a novel source of H2O2 production by S. sanguinis that is independent of pyruvate oxidase (SpxB). Genetic analysis indicated that the glp pathway requires glycerol and a transcriptional regulator, GlpR, for expression and is negatively regulated by PTS, but not the catabolite control protein, CcpA. Conversely, deletion of either manL or ccpA increased expression of spxB and a second, H2O2-non-producing glycerol metabolic pathway (dha), indicative of a mode of regulation consistent with conventional carbon catabolite repression (CCR). In a plate-based antagonism assay and competition assays performed with planktonic and biofilm-grown cells, glycerol greatly benefited the competitive fitness of S. sanguinis against S. mutans. The glp pathway appears to be conserved in several commensal streptococci and actively expressed in caries-free plaque samples. Our study suggests that glycerol metabolism plays a more significant role in the ecology of the oral cavity than previously understood. Commensal streptococci, though not able to use glycerol as a sole carbohydrate for growth, benefit from catabolism of glycerol through production of both ATP and H2O2. ImportanceGlycerol is an abundant carbohydrate found in oral cavity, both due to biological activities of humans and microbes, and as a common ingredient of foods and health care products. However, very little is understood regarding the metabolism of glycerol by some of the most abundant oral bacteria, commensal streptococci. This was in part because most streptococci cannot grow on glycerol as the sole carbon source. Here we show that Streptococcus sanguinis, an oral commensal associated with dental health, can degrade glycerol for persistence and competition through two independent pathways, one of which generates hydrogen peroxide at levels capable of inhibiting a dental pathobiont, Streptococcus mutans. Preliminary studies suggest that several other commensal streptococci are also able to catabolize glycerol, and glycerol-related genes are being actively expressed in human dental plaque samples. Our findings reveal the potential of glycerol to significantly impact microbial homeostasis which warrants further exploration.

microbiology↗

bioRxiv2024

Coxsackievirus group B3 regulates ASS1-mediated metabolic reprogramming and promotes macrophage inflammatory polarization in viral myocarditis

Coxsackievirus group B3 (CVB3) belongs to the genus Enteroviruses of the family Picornaviridae and is the main pathogen underlying viral myocarditis (VMC). No specific therapeutic is available for this condition. Argininosuccinate synthase 1 (ASS1) is a key enzyme in the urea cycle that converts citrulline and aspartic acid to argininosuccinate. Here, we found that CVB3 and its capsid protein VP2 inhibit the autophagic degradation of ASS1 and that CVB3 consumes citrulline to upregulate ASS1, triggers urea cycle metabolic reprogramming, then activates macrophages to develop pro-inflammatory polarization, thereby promoting the occurrence and development of VMC. Conversely, citrulline supplementation to prevent depletion can downregulate ASS1, rescue macrophage polarization, and alleviate the pathogenicity of VMC. These findings provide a new perspective on the occurrence and development of VMC, revealing ASS1 as a potential new target for the treatment of this disease. IMPORTANCEViral myocarditis (VMC) is a common and potentially life-threatening myocardial inflammatory disease, most commonly caused by CVB3 infection. So far, the pathogenesis of VMC caused by CVB3 is mainly focused on two aspects: one is the direct myocardial injury caused by a large number of viral replication in the early stage of infection, and the other is the local immune cell infiltration and inflammatory damage of the myocardium in the adaptive immune response stage. There are few studies on the early innate immunity of CVB3 infection in myocardial tissue, but the appearance of macrophages in the early stage of CVB3 infection suggests that they can play a regulatory role as early innate immune response cells in myocardial tissue. Here, we discovered a possible new mechanism of VMC caused by CVB3, revealed new drug targets for anti-CVB3 and discovered the therapeutic potential of citrulline for VMC.

microbiology↗

bioRxiv2024

Developmental editing control of mRNA ND7 involves KREH2 helicase-dependent gRNAselection and proposed RNA structure in Trypanosoma brucei

Unknown factors regulate mitochondrial U-insertion/deletion (U-indel) RNA editing in procyclic-form (PCF) and bloodstream-form (BSF) T. brucei. This editing, directed by anti-sense gRNAs, creates canonical protein-encoding mRNAs and may developmentally control respiration. Canonical editing by gRNAs that specify protein-encoding mRNA sequences occurs amid massive non-canonical editing of unclear sources and biological significance. We found PCF-specific repression at a major early checkpoint in mRNA ND7, involving helicase KREH2-dependent opposite modulation of canonical and non-canonical "terminator" gRNA utilization. Terminator-programmed editing derails canonical editing and installs proposed repressive structure in 30% of the ND7 transcriptome. BSF-to-PCF differentiation in vitro recreated this negative control. Remarkably, KREH2-RNAi knockdown relieved repression and increased editing progression by reverting canonical/terminator gRNA utilization. ND7 transcripts lacking early terminator-directed editing in PCF exhibited similar negative editing control along the mRNA sequence, suggesting global modulation of gRNA utilization fidelity. The terminator is a "moonlighting" gRNA also associated with mRNA COX3 canonical editing, so the gRNA transcriptome seems multifunctional. Thus, KREH2 is the first identified repressor in developmental editing control. This and our prior work support a model whereby KREH2 activates or represses editing in a stage and substrate-specific manner. KREH2s novel dual role tunes mitochondrial gene expression in either direction during development.

molecular biology↗

bioRxiv2024

The molecular basis of pine wilt disease resistance in Pinus massoniana

Pine wilt disease (PWD), caused by the pine wood nematode (PWN) Bursaphelenchus xylophilus, results in significant economic and ecological damage to Pinus forests and plantations worldwide. Pinus massoniana is the primary host of PWD in southern China, but its response to the PWN remains largely unstudied. Previously, we observed PWD in a P. massoniana nursery that contained over 71 commonly used cultivars. Through field phenotyping, we identified two groups of PWN resistant cultivars. Resistant cultivars (RC) exhibited very low PWN carrying amounts (PCA) and had relatively low mortality, and tolerant cultivars (TC) had high PCA but low mortality. In this study, we confirmed via PWN inoculation assays that the resistant and tolerant cultivars had lower mortality rates, 10% and 11%, respectively, than other cultivars (which had a mortality rate of 83.3%). The RC had a PCA that was significantly lower than that of other cultivars, while the TC exhibited a higher PCA. To explore the molecular mechanisms underlying the response of P. massoniana to PWN, the transcriptome and metabolome of the above cultivars were profiled by high throughput sequencing. As no reference genome is available for P. massoniana, we generated a new full-length transcriptome library with iso-seq. Using the transcriptome and metabolome from different P. massoniana cultivars inoculated with PWN, we found three major PWD resistance strategies. 1) The common response strategy involved three important molecular pathways. First, synthesis of indole-3-acetic acid (IAA) and abcisic acid (ABA) were suppressed during PWN invasion, thus suppressing the synthesis of polysaccharides (especially myo-inositol and trehalose) and (-)-riboflavin through ABC transporters. Second, by inhibiting aspartic acid, the synthesis of arginine and proline through APS5 (aspartate aminotransferase 5) were suppressed. Third, by reducing cysteine, GERD (germacrene D synthase) was up-regulated, and sesquiterpenoid and triterpenoid metabolites were accumulated to resist PWN invasion. 2) The most effective resistance strategy involved the accumulation of reactive oxygen species (ROS), which enhanced jasmonic acid (JA) accumulation and highly induced the expression of chitinase, thus improving resistance to PWN. 3) The tolerance strategy involved the induction of phosphatidylcholine, which promoted flavonoid and anthocyanin synthesis via LPIN (phosphatidate phosphatase), LOX2S (lipoxygenase), and LOX1_5 (linoleate 9S-lipoxygenase), thus significantly inhibiting the pathogenicity of the PWN but not the PCA. These results illustrate the molecular mechanisms by which P. massoniana cultivars resist or tolerate PWN and are of great significance in the prevention and control of PWD.

plant biology↗

bioRxiv2024

Virus-derived Synthetic Riboswitches for Real-time Coronaviruses Sensing in Live Cells

Real-time sensing of viral infection in live cells are crucial for virology research and antiviral development. However, existing methods face challenges of low signal sensitivity and the necessity for viral manipulation and cell fixation. Here, we develop a viral riboswitch (vRibo) approach that employs the viral replicase to induce transgene expression upon viral infection. The vRibo is designed to detect viral real-time transcription and replication in live cells, which in response triggers the translation of reporter and therapeutic genes. By integrating a viral packaging sequence, vRibo can be transmitted to neighboring cells through progeny virions, effectively acting as a Trojan Horse. The negative-strand vRibo elements demonstrated effective detection of several coronaviruses, including 229E and OC43, due to the conservation of cis-acting RNA structures across coronaviruses. Notably, vRibo functions as a dual-purpose system, acting both as an infection detector and inducible antiviral system. vRibo has the potential for basic virology research applications and can be adopted in improving the inducible expression of mRNA medicines for future coronaviruses.

bioengineering↗

bioRxiv2024

Warfarin analogs target disulfide bond-forming enzymes and suggest a residue important for quinone and coumarin binding

Disulfide bond formation has a central role in protein folding of both eukaryotes and prokaryotes. DsbB and VKOR enzymes catalyze the oxidation of the oxidoreductase partner and the formation of de novo disulfide bonds using quinone as cofactor. We have used E. coli and a family of warfarin analogs to study de novo disulfide bond formation. We found that human VKORc1 can function in E. coli by removing two positive residues, allowing the search for novel anticoagulants. One analog was capable of inhibiting both bacterial DsbB and VKOR, and a second one antagonized only the mammalian enzymes. We identified the two amino acid residues responsible for binding. One of these is also essential for quinone binding in both DsbB and VKOR. Our studies highlight a conserved role of this residue in de novo disulfide-generating enzymes and enable the design of novel anticoagulants or antibacterials using coumarin as a scaffold.

microbiology↗

bioRxiv2024

Mutations in HUA2 restore flowering in the Arabidopsis trehalose 6-phosphate synthase1 (tps1) mutant

Plant growth and development are regulated by many factors, including carbohydrate availability and signaling. Trehalose 6-phosphate (T6P), which is synthesized by TREHALOSE-6-PHOSPHATE SYNTHASE 1 (TPS1), is positively correlated with and functions as a signal that informs the cell about the carbohydrate status. Mutations in TPS1 negatively affect the growth and development of Arabidopsis thaliana and complete loss-of-function alleles are embryo lethal, which can be overcome using inducible expression of TPS1 (GVG::TPS1) during embryogenesis. Using EMS mutagenesis in combination with genome re-sequencing we have identified several alleles in the floral regulator HUA2 that restore flowering and embryogenesis in tps1-2 GVG::TPS1. Genetic analyses using a HUA2 T-DNA insertion allele, hua2-4, confirmed this finding. RNA-seq analyses demonstrated that hua2-4 has widespread effects on the tps1-2 GVG::TPS1 transcriptome, including key genes and pathways involved in regulating flowering. Higher order mutants combining tps1-2 GVG::TPS1 and hua2-4 with alleles in the key flowering time regulators FLOWERING LOCUS T (FT), SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1), and FLOWERING LOCUS C (FLC) were constructed to analyze the role of HUA2 during floral transition in tps1-2 in more detail. Taken together, our findings demonstrate that loss of HUA2 can restore flowering and embryogenesis in tps1-2 GVG::TPS1 in part through activation of FT, with contributions of the upstream regulators SOC1 and FLC. Interestingly, we found that mutation of FLC is sufficient to induce flowering in tps1-2 GVG::TPS1. Furthermore, we observed that mutations in HUA2 modulate carbohydrate signaling and that this regulation might contribute to flowering in hua2-4 tps1-2 GVG::TPS1.

plant biology↗

bioRxiv2023

Small-molecule degraders reduce Aβ production through CAPRIN1-mediated lysosomal degradation of APP in Alzheimer iPSC-derived neurons

Overexpression of amyloid precursor protein (APP) is a key driver of amyloid {beta} (A{beta}) pathology, making APP a compelling therapeutic target in Alzheimers disease (AD). Here, we identify small molecules that selectively degrade APP in human neurons through a targeted protein degradation approach. Structural analyses reveal that these compounds act as molecular glues, binding at the interface between cytoplasmic activation/proliferation-associate protein 1 (CAPRIN1) and APP and stabilizing their interaction within a ternary complex. In neurons derived from induced pluripotent stem cells (iPSCs) from sporadic and familial AD patients, these compounds promote CAPRIN1-dependent degradation of both wild-type and mutant APP through the endo-lysosomal pathway. The lead compound, 0152, is blood-brain barrier permeable, and its administration significantly reduces A{beta} production and amyloid burden in the brains of 5xFAD mice. These findings demonstrate that molecular glue degraders harness the CAPRIN1-dependent lysosomal pathway for selective APP degradation, offering a targeted therapeutic strategy for AD.

neuroscience↗

bioRxiv2023

Spatial propagation of temperate phages within and among biofilms

Bacteria form groups comprised of cells and a secreted polymeric matrix that controls their spatial organization. These groups - termed biofilms - can act as refuges from environmental disturbances and from biotic threats, including phages. Despite the ubiquity of temperate phages and bacterial biofilms, live propagation of temperate phages within biofilms has never been characterized on cellular spatial scales. Here, we leverage several approaches to track temperate phages and distinguish between lytic and lysogenic host infections. We determine that lysogeny within E. coli biofilms initially occurs within a predictable region of cell group packing architecture on the biofilm periphery. Because lysogens are generally found on the periphery of large cell groups, where lytic viral infections also reduce local biofilm cell packing density, lysogens are predisposed to disperse into the passing liquid and are over-represented in biofilms formed from the dispersal pool of the original biofilm-phage system. Comparing our results with those for virulent phages reveals that temperate phages have previously unknown advantages in propagating over long spatial and time scales within and among bacterial biofilms.

microbiology↗

bioRxiv2023

Chlamydial protease-like activating factor targets SLC7A11 for degradation to induce ferroptosis and facilitate dissemination.

Chlamydia trachomatis, the most prevalent bacterial agent of sexually transmitted infections, possesses remarkable capacities for dissemination within the host, leading to reproductive health complications. The release of progeny through the orchestrated lysis of host cells plays a crucial role in Chlamydia dissemination, but the underlying molecular mechanisms remain largely elusive. Here, we uncovered a novel mechanism by which Chlamydia induces host cells ferroptosis to facilitate its dissemination. This process involves the degradation of host protein SLC7A11 by the chlamydial protease-like activating factor (CPAF), resulting in glutathione depletion, oxidative damage, and subsequent host cell lysis characterized by lipid peroxidation. Infection with CPAF-deficient strain fails to induce host cells ferroptosis, leading to restricted progeny release. Importantly, inhibiting ferroptosis effectively limits the release of Chlamydia progeny, highlighting its potential as a therapeutic strategy for controlling Chlamydia dissemination. These findings provide insights into the chlamydial conserved dissemination strategy and enhance understanding of its pathogenesis.

microbiology↗

bioRxiv2023

A novel nested gene Aff3ir participates in vascular remodelling by enhancing endothelial cell differentiation in mice

Endothelial integrity in the vasculature is critically maintained by vascular stem/progenitor cells (SPCs) giving rise to endothelial cells (ECs). However, the genes significantly activated during differentiation remain incompletely understood. Based on mouse aorta and vein cDNA library, we unearthed a hitherto unidentified gene nested residing within intron 6 of Aff3, christened as Aff3 intron resident (Aff3ir), upregulated during laminar shear stress-induced ECs differentiation in mouse. Proteomic analysis substantiated the presence of a 45-amino acid(aa) peptide (AFF3IR-ORF1) and 109-aa or 151-aa protein (AFF3IR-ORF2) encoded from two transcript variants. During embryonic development, AFF3IR-ORF1 peaked at E14.5, while AFF3IR-ORF2 displayed a continuous increase until E19.5. In adult mice, AFF3IR-ORF1 was detected in the lung, liver, spleen, and kidney, while AFF3IR-ORF2 was most abundant in the aorta. Furthermore, Western blot and immunofluorescence analyses revealed a specific upregulation of AFF3IR-ORF2, but not AFF3IR-ORF1, three days after femoral artery injury or hindlimb ischemia in vivo. Overexpression of AFF3IR-ORF2 enhanced, while its knockdown attenuated, SPCs differentiation into ECs induced by shear stress or vascular endothelial growth factor in vitro. Notably, the upregulated AFF3IR-ORF2 hindered SPCs proliferation by sequestering minichromosome maintenance complex component 3 in the cytoplasm, thereby shifting the status of SPCs from a pro-proliferation to a pro-differentiation state. In conclusion, our discoveries unveil the novel protein-coding gene Aff3ir as a participant in ECs differentiation, providing fresh insights into the regulation of vascular endothelial integrity.

cell biology↗

bioRxiv2023

IDR-induced CAR condensation improves the cytotoxicity of CAR-Ts against low-antigen cancers

Chimeric antigen receptor (CAR)-T cell-based therapies demonstrate remarkable efficacy for the treatment of otherwise intractable cancers, particularly B-cell malignancies. However, existing FDA-approved CAR-Ts are limited by low antigen sensitivity, rendering their insufficient targeting to low antigen-expressing cancers. To improve the antigen sensitivity of CAR-Ts, we engineered CARs targeting CD19, CD22, and HER2 by including intrinsically disordered regions (IDRs) that promote signaling condensation. The "IDR CARs" triggered enhanced membrane-proximal signaling in the CAR-T synapse, which led to an increased release of cytotoxic factors, a higher killing activity towards low antigen-expressing cancer cells in vitro, and an improved anti-tumor efficacy in vivo. No elevated tonic signaling was observed in IDR CAR-Ts. Together, we demonstrated IDRs as a new tool set to enhance CAR-T cytotoxicity and to broaden CAR-Ts application to low antigen-expressing cancers.

immunology↗

bioRxiv2023

The translation of a short open reading frame product within the human TUBA1B gene regulates cancer cell proliferation by importin-β

Understanding cancer biology is crucial for improving treatment strategies. This study identified TUBA1B-sORF1, a short open reading frame product alternatively translated from the human -tubulin gene (TUBA1B), which has a completely different amino acid sequence from the -tubulin 1B chain. TUBA1B-sORF1 is highly expressed in cancer cell lines and gastric carcinoma. Both methionine-initiated canonical and leucine-initiated noncanonical translations of TUBA1B-sORF1 coexist in cancer cells, and there is a transition between sORF1 and -tubulin translations, evidenced by the TUBA1B-sORF1/-tubulinlow/- subpopulation. Knocking down TUBA1B-sORF1 reduces cancer cell proliferation and tumorigenicity. TUBA1B-sORF1 facilitates protein nuclear translocation, leading to the upregulation of proliferation-promoting genes and downregulation of proliferation-inhibiting genes. Specifically, it forms a complex with importin {beta} and {beta}-catenin, promoting {beta}-catenin nuclear translocation and target gene transcription. These findings reveal that TUBA1B is a polycistronic gene translating at least two entirely different proteins: -tubulin and TUBA1B-sORF1. The variable translation between them may regulate tumorigenesis, making TUBA1B-sORF1 a promising therapeutic target and diagnostic biomarker for cancer treatment.

cancer biology↗

bioRxiv2023

Modifications of Two ESCRT-I Subunits with Distinct Ubiquitin Chains Regulate Plant Immunity

Sensing of pathogen- or microbe-associated molecular patterns (PAMPs/MAMPs) by pattern recognition receptors (PRRs) at the cell surface induces the first layer of host immunity against invading microbial pathogens. The immune receptor FLS2 perceives bacterial flagellin to initiate host immune signaling upon pathogen infections. It has been known that the FLS2 abundance is crucial for plant pattern-triggered immunity. Nevertheless, the underpinning regulatory mechanisms remain largely unclear. In this study, we demonstrate that XBAT35.2 positively modulates the protein level of FLS2. In addition to the Golgi, XBAT35.2 localizes at the plasma membrane and constitutively associates with FLS2, BAK1, and BIK1. Flg22 treatment increases the association of XBAT35.2 with FLS2 and BAK1 but reduces the interaction with BIK1. XBAT35.2 ubiquitinates two key components of the ESCRT-I complex, VPS37-1 and VPS28-2 with K48 and K63-linked polyubiquitin chains respectively, leading to degradation of VPS37-1 and diminished interaction of VPS28-2 with FLS2. Additionally, VPS37-1 and VPS28-2 play redundant, negative roles in FLS2-mediated immunity by promoting vacuolar breakdown of FLS2. Thus, by intercepting the function of VPS28-2 and VPS37-1, XBAT35.2 stabilizes FLS2 for host immunity. Our findings reveal a new regulatory circuit for modulating the FLS2 abundance and deepen our understanding of controlling the homeostasis of cell surface receptors. One-sentence summaryTargeting the ESCRT-I subunits VPS28-2 and VPS37-1 with distinct ubiquitin chains by the E3 ligase XBT35.2 stabilizes FLS2 and positively modulates plant immunity.

plant biology↗

bioRxiv2023

Genetic Characterization of Glyoxalase Pathway in Oral Streptococci and its Contribution to Interbacterial Competition

Substantial quantities of Reactive Electrophile Species (RES), including methylglyoxal and glyoxal, are generated by microbes and humans. To understand the impact of RES on oral microbial homeostasis, genetic analyses were performed on the glyoxalase pathway in Streptococcus mutans (SMU) and Streptococcus sanguinis (SSA). Loss of glyoxalase I (LguL), which catalyzes the rate-limiting reaction in RES degradation, reduced methylglyoxal and glyoxal tolerance to a far greater extent in SMU than in SSA, decreasing the competitiveness of SMU over SSA in planktonic cultures. MICs showed an overall greater RES tolerance by SMU than SSA; a finding consistent with the ability of methylglyoxal to induce the expression of lguL in SMU, but not in SSA. Computational analysis identified a novel paralogue of LguL in most streptococci represented by SMU.1112c in SMU. {Delta}SMU.1112c showed a minor decrease in methylglyoxal tolerance under certain conditions, but a significant growth defect on fructose; a phenotype reversed by the deletion of a fructose-1-phosphate-generating sugar: phosphotransferase system or addition of glutathione (GSH) to the medium. Further, deletion of the glucose-PTS in SMU increased RES tolerance partly through enhanced expression of the pyruvate-dehydrogenase complex. Consistent with the requirement of GSH for methylglyoxal detoxification, deletion of glutathione synthetase (gshAB) in SMU significantly reduced RES resistance. This study reveals the critical roles of RES in fitness and interbacterial competition and the effects of PTS in modulating RES metabolism. The fact that RES may impact the pathogenic potential of the oral microbiome via differential effects on beneficial and pathogenic species warrants further investigation. ImportanceAs highly reactive byproducts of sugar metabolism, very little is known regarding the contribution of methylglyoxal or related aldehyde compounds to oral health. The need to better understand the influence of these reactive electrophile species (RES) to microbial physiology and ecology is made more urgent by the widespread condition of hyperglycemia in humans, which is associated with elevated RES levels. Our study showed a significantly greater ability of a major caries pathobiont, Streptococcus mutans, to tolerate methylglyoxal and glyoxal than many commensal oral streptococci. Genetic analysis of methylglyoxal degradation in the pathobiont and commensals identified significant differences in genetic structure and gene regulation patterns that could contribute to differential fitness by constituents of the dental microbiota and ecologic shift in the presence of RES.

microbiology↗