Biology subjects

Torres, M. A.

Publications and source records attributed to Torres, M. A..

7 recordsLinked to original sources

bioRxiv2026

A molecular description of plant cellulose biosynthesis inhibition

Dictating cell growth and morphology, cellulose biosynthesis is intrinsic to plant cell biology. Accordingly, cellulose biosynthesis inhibitors (CBIs) are important herbicides, toxins, and experimental tools. We currently lack mechanistic understanding of CBI activity, preventing engineering of herbicide selectivity and disease immunity. Contrasting classical inhibitors, we unexpectedly identify the unusual Streptomyces phytotoxin thaxtomin A as the only in vitro-active CBI, with unprecedentedly broad-spectrum activity against various cellulose synthase enzymes. High-resolution cryo-electron microscopy reveals that thaxtomin A leverages exotic nitroaromatic chemistry to target a strictly conserved site in cellulose synthases polysaccharide secretion channel. Strikingly, in vitro biosynthesis and biophysical assays demonstrate thaxtomin As near-picomolar efficacy. Plant and algal systems reveal that its global arrest of cellulose biosynthesis produces an osmotically driven crisis in expanding cells. Finally, site-directed mutagenesis generates the first toxin-resistant cellulose synthase. Our results underscore celluloses critical function in plant lifeforms and inform efforts to inhibit related enzymes across kingdoms.

plant biology↗

bioRxiv2025

Glycan recognition by a plant sentinel immune receptor

Pathogens target and degrade the extracellular matrix surrounding plant cells. A central question is how cell wall-derived damage-associated molecular patterns (DAMPs) are recognized and integrated to trigger immune responses. We address this question by determining the structure of the multidomain receptor IGP1 in both apo form and bound to the cellulose-derived DAMP cellotriose. Structural analyses reveal that constitutive Leucine Rich Repeat-malectin interactions preconfigure IGP1 for ligand recognition and that the receptor features a highly specific sugar-binding pocket in the LRR domain capable of distinguishing fine variations in glycan structures. By directly sensing cello-oligomers, IGP1 acts as a cell wall sentinel that links pathogen-induced wall degradation to immune alerting, equipping plants to mount rapid and robust defense responses.

plant biology↗

bioRxiv2024

The clumped isotope signatures of multiple methanogenesis metabolisms

Methane is a potent greenhouse gas, an important energy source, and a potential biosignature on extraterrestrial planetary bodies. The relative abundances of doubly substituted ("clumped") methane isotopologues (13CH3D and 12CH2D2) offer important information on the sources and sinks of methane. However, the clumped isotope signatures of microbially produced methane from different methanogenic pathways lack a systematic investigation. In this study, we provide a dataset encompassing the relative isotopologue abundances produced by hydrogenotrophic, methylotrophic, acetoclastic, and methoxydotrophic methanogenesis. We find that a statistical "combinatorial effect" generates significant differences in 12CH2D2 compositions between hydrogenotrophic methanogenesis and other pathways. The thermodynamic drive of methanogenic reactions and phylogenetic affiliation may also influence the isotope compositions of methane. Our study provides new experimental constraints on the isotope signatures of different microbial methanogenic pathways, and evidence of the mechanisms responsible for the observed differences. TeaserA novel stable isotope tool to track and differentiate sources of biological methane.

microbiology↗

bioRxiv2022

Cultivation of plant-growth promoters in vinasse: contributions for a circular and green economy

Vinasse is a by-product with a key role in the circular economy. In this work, we analyze sugarcane vinasse as culture medium for obtaining single and mixed inoculants. Trichoderma harzianum was cultured in single and sequential co-culture with Pseudomonas capeferrum or Rhizobium sp. Fungal biomass was higher in vinasse than in a laboratory medium. Residual vinasses presented almost neutral pH and lower conductivities and toxicity than raw vinasse. Fertigation with residual vinasses improves characteristics of soil evidenced in the total N, cation exchange capacity, urease and acid phosphatase, and the microbial metabolic diversity, in comparison to raw vinasse. The evaluation of the treatment indicates that vinasse is suitable for the production of inoculants containing T. harzianum and that the co-culture with P. capeferrum improves the characteristics of the residual vinasse in comparison to Rhizobium sp. Obtaining this valuable biomass in vinasse is relevant for the circular and green economy.

bioengineering↗

bioRxiv2022

A group of Arabidopsis thaliana Leucine Rich Repeat-Malectin Receptor Kinases are required for the activation of immune responses triggered by cellulose and mixed-linked glucan oligosaccharides

Plant immune system perceives through the extracellular ectodomains (ECDs) of Pattern Recognition Receptors (PRRs) a diversity of carbohydrate ligands from plant and microbial cell walls, which activate Pattern-Triggered Immunity (PTI). Among these ligands are oligosaccharides derived from mixed-linked {beta}-1,3/{beta}-1,4-glucans (MLGs, e.g., {beta}-1,4-D-(Glc)2-{beta}-1,3-D-Glc, MLG43) and cellulose (e.g., {beta}-1,4-D-(Glc)3, CEL3). The mechanisms of perception of carbohydrates by plants are poorly characterized, with the exception of that determining recognition of fungal chitin oligosaccharides (e.g., {beta}-1,4-D(GlcNAc)6, CHI6) that involves several PRRs with LysM-ECDs that function as receptor or co-receptors. Here, we describe the isolation and characterization of Arabidopsis thaliana mutants impaired in glycan perception (igp), which are defective in PTI activation mediated by MLG43 and CEL3, but not CHI6. igp1-igp4 are altered in receptor-like kinases [RLKs: AT1G56145 (IGP1), AT1G56130 (IGP2/3), and AT1G56140 (IGP4)] with Leucine-Rich-Repeat (LRR) and Malectin (MAL) domains in their ECDs. igp4 is a T-DNA insertional, loss of function mutant whereas igp1 and the allelic igp2/igp3 harbour point mutations (E906K and G773E, respectively) in their kinase domains, which impact their structure and surface electrostatic potential as revealed by in silico structural analyses. Notably, Isothermal Titration Calorimetry assays with purified ECD-RLKs showed that AT1G56145 binds with high affinity CEL3 (Kd = 1.19 {+/-} 0.03 M) and cellopentaose (Kd = 1.40 {+/-} 0.01 M), but not MLG43, supporting AT1G56145 function as a plant PRR for cellulose oligosaccharides. Our data suggest that these LRR-MAL RLKs are receptor/co-receptors of a novel mechanism of perception of cellulose and MLG-derived oligosaccharides and PTI activation in Arabidopsis thaliana. Significance StatementNew oligosaccharides that trigger plant immunity have been described recently, but the mechanisms of perception of these glycans are unknown. We describe here three Arabidopsis thaliana receptor kinases (AT1G56130, AT1G56140, and AT1G56145) with Leucine Rich Repeat (LRR) and Malectin (MAL) domains in their extracellular ectodomains (ECDs), which function as Pattern Recognition Receptors (PRRs) triggering immune response mediated by oligosaccharides from cellulose ({beta}-1,4-glucan) and mixed-linked {beta}-1,3/1,4-glucans (MLGs) of plant and microbial cell walls. The ECD-AT1G56145 binds cellulose oligosaccharides, but not MLGs, supporting its function as a novel receptor of carbohydrate ligands in plants. Our data indicate that these LRR-MAL-PRRs control a complex mechanism of oligosaccharides perception and immune activation that differs from that of fungal chitin oligosaccharides recognition which involves LysM-PRRs.

plant biology↗

bioRxiv2021

Insight in the quorum sensing-driven lifestyle of the non-pathogenic Agrobacterium tumefaciens 6N2 and the interactions with the yeast Meyerozyma guilliermondii

Agrobacterium tumefaciens is considered a prominent phytopathogen, though most isolates are nonpathogenic. Agrobacteria can inhabit plant tissues interacting with other microorganisms. Yeasts are likewise part of these communities. We analyzed the quorum sensing (QS) systems of A. tumefaciens strain 6N2, and its relevance for the interaction with the yeast Meyerozyma guilliermondii, both sugarcane endophytes. We show that strain 6N2 is nonpathogenic, produces OHC8-HSL, OHC10-HSL, OC12-HSL and OHC12-HSL as QS signals, and possesses a complex QS architecture, with one truncated, two complete systems, and three additional QS-signal receptors. A proteomic approach showed differences in QS-regulated proteins between pure (64 proteins) and dual (33 proteins) cultures. Seven proteins were consistently regulated by quorum sensing in pure and dual cultures. M. guilliermondii proteins influenced by QS activity were also evaluated. Several up- and down- regulated proteins differed depending on the bacterial QS. These results show the importance of the QS regulation in the bacteria-yeast interactions. HighlightsThe avirulent A. tumefaciens 6N2 has two replicons and a complex QS architecture The profile of QS-regulated proteins is modified in dual cultures with Pa. laurentii The bacterial QS activity alters the proteome of the yeast Pa. laurentii

microbiology↗

bioRxiv2020

Comprehensive database of secondary metabolites from cyanobacteria

Cyanobacteria form harmful mass blooms in freshwater and marine environments around the world. A range of secondary metabolites has been identified from cultures of cyanobacteria and biomass collected from cyanobacterial bloom events. A comprehensive database is necessary to correctly identify cyanobacterial metabolites and advance research on their abundance, persistence and toxicity in natural environments. We consolidated open access databases and manually curated missing information from the literature published between 1970 and March 2020. The result is the database CyanoMetDB, which includes more than 2000 entries based on more than 750 literature references. This effort has more than doubled the total number of entries with complete literature metadata and structural composition (SMILES codes) compared to publicly available databases to this date. Over the past decade, more than one hundred additional secondary metabolites have been identified yearly. We organized all entries into structural classes and conducted substructure searches of the provided SMILES codes. This approach demonstrated, for example, that 65% of the compounds carry at least one peptide bond, 57% are cyclic compounds, and 30% carry at least one halogen atom. Structural searches by SMILES code can be further specified to identify structural motifs that are relevant for analytical approaches, research on biosynthetic pathways, bioactivity-guided analysis, or to facilitate predictive science and modeling efforts on cyanobacterial metabolites. This database facilitates rapid identification of cyanobacterial metabolites from toxic blooms, research on the biosynthesis of cyanobacterial natural products, and the identification of novel natural products from cyanobacteria. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=125 SRC="FIGDIR/small/038703v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@3504f7org.highwire.dtl.DTLVardef@d92680org.highwire.dtl.DTLVardef@6ea103org.highwire.dtl.DTLVardef@10cd983_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioinformatics↗