Biology subjects

Bueno, E.

Publications and source records attributed to Bueno, E..

3 recordsLinked to original sources

bioRxiv2021

Mutation of lipoprotein processing pathway gene lspA or inhibition of LspA activity by globomycin increases MRSA resistance to -lactam antibiotics

The Staphylococcus aureus cell envelope comprises numerous components, including peptidoglycan (PG), wall teichoic acids (WTA), lipoteichoic acids (LTA), targeted by antimicrobial drugs. MRSA resistance to methicillin is mediated by the mecA-encoded {beta}-lactam-resistant transpeptidase, penicillin binding protein 2a (PBP2a). However, PBP2a-dependent {beta}-lactam resistance is also modulated by the activity of pathways involved in the regulation or biosynthesis of PG, WTA or LTA. Here, we report that mutation of the lipoprotein signal peptidase II gene, lspA, from the lipoprotein processing pathway, significantly increased {beta}-lactam resistance in MRSA. Mutation of lgt, which encodes diacylglycerol transferase (Lgt) responsible for synthesis of the LspA substrate did not impact {beta}-lactam susceptibility. Consistent with previous reports, lgt and lspA mutations impaired growth in chemically defined media, but not in complex broth. MRSA exposure to the LspA inhibitor globomycin also increased {beta}-lactam resistance. Mutation of lgt in an lspA background restored {beta}-lactam resistance to wild type. The lspA mutation had no effect on PBP2a expression, PG composition or autolytic activity indicating a potential role for WTA or LTA. The lspA and lgt mutants exhibited marginally increased resistance to the D-alanine pathway inhibitor D-cycloserine. In addition, mutation of lgt and multicopy lspA expression, but not mutation of lspA, significantly increased susceptibility to the lipoteichoic acid synthase inhibitor Congo red revealing complex interplay between lipoprotein processing mutations and the expression/stability of cell surface glycopolymers. These findings indicate that accumulation of the LspA substrate, diacylglyceryl lipoprotein, increases MRSA resistance to {beta}-lactam antibiotics through impacts on cell envelope components other than PG.

microbiology↗

bioRxiv2020

The spore of the beans: Spatially explicit models predict coffee rust spread in fragmented landscapes

Landscape structure influences the spread of plant pathogens, primarily by affecting pathogen dispersal. Coffee leaf rust (Hemileia vastatrix), a fungal disease that causes heavy economic losses in the coffee industry, is likely to be affected by landscape structure via dispersal of its wind-borne spores. Previous studies have found positive associations between leaf rust incidence and the proportion of pasture cover, suggesting that deforestation may facilitate rust spore dispersal. We explored this idea by modeling the spread of rust transmission in simulated landscapes. Specifically, we modeled within-patch transmission using a probabilistic cellular automata model, and between-patch transmission using a random walk with spore movement inhibited by forest canopy cover. We used this model to understand how the spread of coffee rust is affected by: 1) clustering of coffee plants, 2) clustering of deforestation, and 3) proportion of landscape deforestation. We found that clustering of coffee plants is the primary driver of rust transmission, affecting the likelihood and severity of rust outbreak. Deforestation is important in landscapes with high clustering of coffee: rust outbreaks are more severe in landscapes with a higher proportion of deforested areas, and more variable in landscapes where deforested areas are more evenly dispersed throughout the landscape.

ecology↗

bioRxiv2020

Genetic dissection of the fermentative and respiratory contributions supporting Vibrio cholerae hypoxic growth

Both fermentative and respiratory processes contribute to bacterial metabolic adaptations to low oxygen tension (hypoxia). In the absence of O2 as a respiratory electron sink, many bacteria utilize alternative electron acceptors such as nitrate (NO3-). During canonical NO3- respiration, NO3- is reduced in a stepwise manner to N2 by a dedicated set of reductases. Vibrio cholerae, the etiological agent of cholera, only requires a single periplasmic NO3- reductase (NapA) to undergo NO3- respiration, suggesting that the pathogen possesses a non-canonical NO3- respiratory chain. Here, we used complementary transposon-based screens to identify genetic determinants of general hypoxic growth and NO3- respiration in V. cholerae. We found that while the V. cholerae NO3- respiratory chain is primarily composed of homologues of established NO3- respiratory genes, it also includes components previously unlinked to this process, such as the Na+-NADH dehydrogenase Nqr. The ethanol-generating enzyme AdhE was shown to be the principal fermentative branch required during hypoxic growth in V. cholerae. Relative to single adhE or napA mutant strains, a V. cholerae strain lacking both genes exhibited severely impaired hypoxic growth in vitro and in vivo. Our findings reveal the genetic bases for interactions between disparate energy production pathways that support pathogen fitness in shifting conditions. Such metabolic specializations in V. cholerae and other pathogens are potential targets for antimicrobial interventions. IMPORTANCEBacteria reprogram their metabolism in environments with low oxygen levels (hypoxia). Typically, this occurs via regulation of two major, but largely independent, metabolic pathways-fermentation and respiration. Here, we found that the diarrheal pathogen Vibrio cholerae has a respiratory chain for NO3- that consists largely of components found in other NO3- respiratory systems, but also contains several proteins not previously linked to this process. Both AdhE-dependent fermentation and NO3- respiration were required for efficient pathogen growth in both laboratory conditions and in an animal infection model. These observations provide genetic evidence for fermentative-respiratory interactions and identify metabolic vulnerabilities that may be targetable for new antimicrobial agents in V. cholerae and related pathogens.

microbiology↗