Biology subjects

Rodriguez Gallo, M. C.

Publications and source records attributed to Rodriguez Gallo, M. C..

4 recordsLinked to original sources

bioRxiv2025

Chemical Inhibition of Splicing-Related Protein Kinases Reveals Phosphorylation-Driven Regulation of RNA Alternative Splicing in Arabidopsis Seedlings

Serine / arginine (SR) protein kinases (SRPKs) are capable of transmitting external signals to the spliceosome by phosphorylating SR proteins. In plants, few studies have looked at the regulation of RNA splicing by post-translational modification (PTMs), despite the spliceosome and splicing factor proteins exhibiting extensive phosphorylation. Many of these PTM events have the potential to dramatically change the expression of various genes, such as those involved in abiotic stress. Here, we sought to explore the regulatory function of Arabidopsis thaliana SRPKs in the context of RNA alternative splicing. To do so, we utilized four well-known and well-characterized chemical inhibitors specifically designed to target and inhibit SRPK enzymatic activity. Our data found that SRPK chemical inhibitors SPHINX31 and SRPIN340 induced shorter root development phenotypes and an abolishment of root hair formation. Using a multi-omics approach combining transcriptomics and phosphoproteomics, we find extensive changes in the splicing of genes involved in root development, RNA splicing, cytoskeletal organization, and cell differentiation. We also reveal splicing factors exhibiting differential alternative splicing as well as a down-regulated in their phosphorylation status. Overall, our data indicate that AtSRPKs phosphorylate diverse splicing factors and influence the alternative splicing of genes involved in root development and a wide-range of related pathways.

plant biology↗

bioRxiv2025

Prolific release of S-layer units and associated proteins by the methanotrophic bacterium Methylomicrobium album BG8

Some methanotrophs synthesize S-layers that overlay their outer membrane. TEM imaging revealed that Methylomicrobium album BG8 constitutively sheds abundant S-layer units, a phenotype not found in 7 other methanotrophs, even though Methylotuvimicrobium buryatense 5GB1 produces a similar structure. Release of S-layer units occurred regardless of carbon (methane or methanol) or nitrogen (ammonium or nitrate) source, with 50X trace metals, under copper deprivation, and at all growth phases. The released S-layer units were isolated from the culture medium of M. album BG8 by density gradient centrifugation for proteome analysis. The proteome revealed the S-layer protein subunits, transporters for calcium uptake including TolC and Repeats-in-Toxin (RTX) proteins, transporters for uptake for cobalamin and siderophores, cell wall biogenesis proteins, and proteins with Type I secretion system (T1SS) target domains. M. album BG8 adapted to grow at pH 4 lost its S-layer and genome analysis revealed a frameshift mutation plus reduced expression of the S-layer unit gene plus the deletion and almost no expression of an S-layer-associated porin gene. Together, the results suggest that the biogenesis and secretion of M. album BG8 S-layer is mediated by its associated T1SS, the S-layer possesses metal acquisition functions, and low pH adaptation of M. album BG8 results in loss of S-layer, likely due to reduced, or incomplete, expression of S-layer units and loss of an associated porin. The involvement of the T1SS and shedding phenotype of the S-layer in M. album BG8 could be applied towards selective secretion of proteins and other factors of bioindustrial interest. ImportanceThe methanotrophic bacterium M. album BG8 produces and sheds large quantities of S-layer units into the culture medium regardless of carbon or nitrogen source, metal availability or growth phase. Of the 8 methanotrophic bacteria screened, only M. album BG8 possessed this phenotype. Proteomics analysis of density gradient purified culture supernatant identified the S-layer protein units and proteins involved in metal uptake and S-layer biogenesis, some with secretion signals for the T1SS. M. album BG8 adapted to grow at low pH lost production of its S-layer due to mutations in the genes encoding S-layer units and an associated porin. Better understanding of M. album BG8 S-layer production and its shedding phenotype could be harnessed for exporting expressed proteins and bioproducts of industrial interest for ease of collection and downstream processing.

microbiology↗

bioRxiv2024

B4 Raf-like MAPKKK RAF24 regulates Arabidopsis thaliana flowering time through HISTONE MONO-UBIQUITINATION 2

The timing of flowering is a critical agronomic trait governed by a number of external cues. Despite our genetic understanding of flowering time being well established, we have a limited understanding of how these signals are transmitted to different flowering genes through protein phosphorylation. Here, we characterize a novel B4 Raf-like MAPKKK protein kinase called RAF24, whose mutation results in an early flowering phenotype. Comparative analysis to related B4 Raf-like MAPKKKs indicates that RAF24 uniquely affects flowering time, while phosphoproteome analyses found RAF24 impacts the phosphorylation status of proteins involved in distinct flowering pathways. In particular, we found the RING-type ubiquitin ligase HISTONE MONO-UBIQUITINATION 2 (HUB2) to possess the largest phosphorylation change in raf24 deficient plants relative to wild-type Arabidopsis and that RAF24 suppresses ligase activity of HUB2 in order to maintain appropriate levels of H2Bub1. Furthermore, we found that RAF24 regulates HUB2 phosphorylation through subclass I and III SUCROSE NON-FERMENTING KINASE 2 (SnRK2) protein kinases; known substrates of B4 RAF-like MAPKKKs. Lastly, using a combination of phospho-mimetic and -ablative plant lines, we validate the importance of HUB2 phosphorylation at S314 in regulating flowering time. Collectively, our findings implicate RAF24 as a higher-order flowering regulator, while further implicating HUB2 as a centerpiece of flowering regulation.

plant biology↗

bioRxiv2024

Catalytically inactive subgroup VIII receptor-like cytoplasmic kinases regulate the immune-triggered oxidative burst in Arabidopsis thaliana

Protein kinases are key components of multiple cell signaling pathways. Several protein kinases of the receptor-like cytoplasmic kinase (RLCK) family have demonstrated roles in immune and developmental signaling across various plant species, making them a family of interest in the study of phosphorylation-based signal relay. Here, we present our investigation of a subfamily of RLCKs in Arabidopsis thaliana. Specifically, we focus on subgroup VIII RLCKs: MAZ and its paralog CARK6, as well as CARK7 and its paralog CARK9. We found that both MAZ and CARK7 associate with the calcium-dependent protein kinase CPK28 in planta, and furthermore that CPK28 phosphorylates both MAZ and CARK7 on multiple residues in areas that are known to be critical for protein kinase activation. Genetic analysis suggests redundant roles for MAZ and CARK6 as negative regulators of the immune-triggered oxidative burst. We find evidence that supports homo- and hetero-dimerization between CARK7 and MAZ, which may be a general feature of this protein family. Multiple biochemical experiments suggest that neither MAZ nor CARK7 demonstrate catalytic protein kinase activity in vitro. Interestingly, we find that a mutant variant of MAZ incapable of protein kinase activity is able to complement maz-1 mutants, suggesting noncatalytic roles of MAZ in planta. Overall, our study identifies subgroup VIII RLCKs as new players in Arabidopsis immune signaling and highlights the importance of noncatalytic functions of protein kinases.

plant biology↗