Biology subjects

Villa-Tanaca, L.

Publications and source records attributed to Villa-Tanaca, L..

3 recordsLinked to original sources

bioRxiv2025

Uncovering the Genomic and Phenotypic Landscape of Nitrogen-Fixing Rhizobium miluonense WD29 in Free-Living Conditions

The endophytic bacterial strain Rhizobium miluonense WD29, isolated from the giant Mexican landrace maize Jala, demonstrates remarkable nitrogen fixation capabilities in free-living conditions. Through comprehensive genomic and phenotypic analyses, we characterized its unique attributes and potential applications in sustainable agriculture. Whole genome sequencing revealed a 6.8 Mb genome with 59.7% GC content, comprising 6,908 protein-coding genes, 3 rRNA genes, 46 tRNA sequences, and 146 insertion elements. Comparative genomic analysis showed that WD29 contains unique gene clusters associated with nitrogen fixation, biofilm formation, and plant growth promotion. The strain exhibits notable plant growth-promoting characteristics, including phosphate solubilization (26.1 {+/-} 1.9 {micro}g/mL), IAA production (19.7 {+/-} 2.5 {micro}g/mL), and multiple metallophore production capabilities (21.1-62.4% chelation for various metals). Significantly, R. miluonense WD29 demonstrates efficient nitrogen fixation in free-living conditions, with rates up to 21.7 {+/-} 2.3 nmol h-1 of reduced acetylene at optimal galactose concentrations (1 g/L), coupled with substantial exopoly-saccharide production (0.8 {+/-} 0.076 g/mL). The strains genome harbors at least 9 genes involved in exopolysaccharide biosynthesis, likely contributing to its biofilm formation capability and enhanced nitrogen fixation efficiency. Additionally, WD29 shows remarkable environmental adaptability, possessing genes for heavy metal resistance and various stress responses. These findings highlight R. miluonense WD29s potential as a valuable biofertilizer for sustainable agriculture, particularly for non-leguminous crops like maize, and demonstrate the importance of studying nitrogen-fixing bacteria isolated from traditional agricultural systems.

microbiology↗

bioRxiv2025

Maize plant infection by Ustilago maydis is regulated by the Fungal Sulfur Metabolism.

The sulfur metabolism is tightly regulated in cells. Cysteine, at physiological concentrations, plays a crucial role in protein assembly, as well as in coenzyme and metabolic intermediate synthesis. Additionally, cysteine is biotransformed into H2S, a gasotransmitter with several roles on cells, ranging from regulating mitochondrial metabolism to producing metabolic intermediates and mediating post-translational modification of proteins. While H2S has been shown to participate in the infection processes of animal pathogenic fungi, its role in phytopathogenic fungi remains unexplored. Here, we describe the conditions required to induce endogenous production of H2S in plant pathogenic fungi Ustilago maydis. Under these conditions, we observed an increased infection rate and more pronounced symptoms in maize plants. A label-free proteomic assay to examine adaptations of U. maydis under H2S-producing conditions shown an increased expression of extracellular enzymes required for virulence and mitochondrial proteins related to cellular respiration, ATP synthesis, and fatty acid degradation, along with enhanced expression of proteins involved in proteasomal degradation. Conversely, we found reduced expression of proteins associated with antioxidant responses, glycolysis, and the pentose phosphate pathway. These mitochondrial protein alterations correlated with increased mitochondrial biogenesis, ultrastructural changes, inhibition of the cytochrome respiratory pathway, and elevated activity of an alternative oxidase. Additionally, H2O2 production increased, while the enzymatic capacity for its detoxification decreased. Impaired lipid accumulation and altered intracellular distribution were also observed. Thus, in U. maydis, the modulation of cysteine metabolism regulates mitochondrial function, protein expression, lipid metabolism and infectious processes. Author SummaryUstilago maydis is a basidiomycete fungus that infects corn plants, inducing tumor formation. While in some countries this infection causes significant losses in maize crops, in Mexico, U. maydis, known as "huitlacoche," is celebrated as a culinary delicacy with important nutritional value. Additionally, it serves as an interesting model for studying infection by dimorphic phytopathogenic fungi. Animal models of fungal pathogenesis show that hydrogen sulfide (H2S), whether exogenously provided or induced by supplementation with its precursor cysteine, plays a role in infection processes in both the pathogen and the host cell. In this study, we explored the role of cysteine in the morphology, metabolism, and pathogenicity of U. maydis. Our findings indicate that cysteine treatment triggers an overproduction of H2S, alters mitochondrial morphology and nitrogen metabolism, and disrupts the oxidative balance in U. maydis. Furthermore, fungi to cysteine enhance tumor formation and anthocyanins accumulation in Zea mays plants. These findings suggest that H2S may play a key role in the infection efficiency of phytopathogenic fungi.

biochemistry↗

bioRxiv2021

Antifungal activity of fibrate-based compounds and substituted pyrroles inhibiting the enzyme 3-hydroxy-methyl-glutaryl-CoA reductase of Candida glabrata (CgHMGR), and decreasing yeast viability and ergosterol synthesis

Due to the emergence of multi-drug resistant strains of yeasts belonging to the Candida genus, there is an urgent need to discover antifungal agents directed at alternative molecular targets. The aim of the current study was to evaluate the capacity of synthetic compounds to inhibit the Candida glabrata enzyme denominated 3-hydroxy-methyl-glutaryl-CoA reductase (CgHMGR), and thus affect ergosterol synthesis and yeast viability. One series of synthetic antifungal compounds were analogues to fibrates, a second series had substituted 1,2-dihydroquinolines and the third series included substituted pyrroles. -asarone-related compounds 1c and 5b with a pyrrolic core were selected as the best antifungal candidates. Both inhibited the growth of fluconazole-resistant C. glabrata 43 and fluconazole-susceptible C. glabrata CBS 138. A yeast growth rescue experiment based on the addition of exogenous ergosterol showed that the compounds act by inhibiting the mevalonate synthesis pathway. A greater recovery of yeast growth occurred for the C. glabrata 43 strain and after the 1c (versus 5b) treatment. Given that the compounds decreased the ergosterol concentration in the yeast strains, they probably target the ergosterol synthesis. According to the docking analysis, the inhibitory effect of the 1c and 5b could possibly be mediated by their interaction with the amino acid residues of the catalytic site of CgHMGR. Since 1c displayed higher binding energy than -asarone and 5b, it is a good candidate for further research, which should include structural modifications to increase its specificity and potency as well as in vivo studies on its effectiveness at a therapeutic dose. HIGHLIGHTSO_LIFibrate-based and pyrrole-containing compounds were tested as C. glabrata inhibitors. C_LIO_LIThe best inhibitor from fibrate was 1c and from pyrroles was 5b. C_LIO_LIThese agents inhibited C. glabrata growth better than the reference antifungals. C_LIO_LIThey also inhibited ergosterol synthesis by the two C. glabrata strains tested. Experimental C_LI

microbiology↗