Biology subjects

Dugar, G.

Publications and source records attributed to Dugar, G..

3 recordsLinked to original sources

bioRxiv2026

Modulation of rob expression accelerates development of antibiotic resistance in Yersinia enterocolitica

Multidrug-resistant bacteria pose a severe threat to global health. Mutations in transcriptional regulators accelerate the emergence of multidrug resistance and may have a crucial impact on pathogen evolvability under antibiotic exposure. Here, we investigate these dynamics in the bacterial pathogen Yersinia enterocolitica. In this organism, we identified a high-frequency de novo mutation in the promoter of an AraC/XylS-family transcriptional regulator, Rob. This mutation arose independently during resistance evolution against three of six antibiotic classes. Sequence and structure alignments indicate that Rob is a previously uncharacterized, lineage-specific regulator in Y. enterocolitica, featuring a conserved promoter architecture. This promoter mutation resulted in robust rob overexpression, leading to the activation of multiple downstream efflux- and membrane-associated pathways. This regulatory mutation emerges early and shapes the acquisition of tetracycline resistance, while also enhancing high-level enrofloxacin resistance in combination with canonical mutations in gyrA and parC. Despite being favored under antibiotic selection, rob overexpression is costly, resulting in counter-selection of the -57 G>A rob allele in the absence of antibiotics. Together, these findings identify Rob as a Yersinia-specific efflux regulator and demonstrate how regulatory mutations can transiently accelerate antibiotic resistance. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/707304v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@107aa88org.highwire.dtl.DTLVardef@4ccd66org.highwire.dtl.DTLVardef@411e2aorg.highwire.dtl.DTLVardef@1235fbc_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2025

Comprehensive architecture of the bacterial RNA interactome

RNA-based regulation pervades bacteria, but obtaining a transcriptome-wide map of native RNA contacts has been technically challenging. Here TRIC-seq (Total RNA Interaction Capture) is introduced as an in situ, genetics-free proximity-ligation approach that preserves cellular context and resolves both intramolecular (structure) and intermolecular (regulatory) RNA contacts at high resolution and specificity. In Escherichia coli, TRIC-seq captures thousands of unique interactions, recovering known small RNA (sRNA) regulons and revealing non-canonical contacts among rRNAs, tRNAs and mRNAs, including a widespread interaction between the 3' extension of 16S rRNA and 5UTRs of stress-response mRNAs. Unsupervised analysis exposes a highly modular interactome organized by sRNA hubs. Beyond E. coli, TRIC-seq maps interactomes in diverse bacteria, enabling de novo discovery of novel sRNAs along with their targets. Finally, TRIC-seq uncovers a large, functionally coherent cohort of stress-related mRNAs that co-aggregate and are depleted for ribosome contacts.

microbiology↗

bioRxiv2022

The conserved protein WhiA influences branched-chain fatty acid precursors in Bacillus subtilis

The conserved WhiA protein family is present in most Gram-positive bacteria and plays a role in cell division. WhiA contains a DNA-binding motive and has been identified as a transcription factor in actinomycetes. In Bacillus subtilis, the absence of WhiA influences cell division and chromosome segregation, however, it is still unclear how WhiA influences these processes, but the protein does not seem to function as transcription factor in this organism. To further investigate the function of WhiA in B. subtilis, we performed a yeast two-hybrid screen to find interaction partners, and a Hi-C experiment to reveal possible changes in chromosome conformation. The latter experiment indicated a reduction in short range chromosome interactions, but how this would affect either cell division or chromosome segregation is unclear. Based on adjacent genes, a role in carbon metabolism was put forward. To study this, we measured exometabolome fluxes during growth on different carbon sources. This revealed that in {Delta}whiA cells the pool of branched-chain fatty acid precursors is lower. However, the effect on the membrane fatty acid composition was minimal. Transcriptome data could not link the metabolome effects to gene regulatory differences. IMPORTANCEWhiA is a conserved DNA binding protein that influences cell division and chromosome segregation in the Gram-positive model bacterium B. subtilis. The molecular function of WhiA is still unclear, but a previous study has suggested that the protein does not function as a transcription factor. In this study, we used yeast two-hybrid screening, chromosome conformation capture analysis, metabolomics, transcriptomics and fatty acid analysis to obtain more information about the workings of this enigmatic protein.

microbiology↗