bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2021.10.29.466536

Silencing of an efflux pump coding gene decreases the efflux rate of pyrazinoic acid in Mycobacterium smegmatis

Quinones-Garcia, S.·Gilman, R. H.·Sheen, P.·Zimic, M.
View original source ↗Export metadata ↓

Abstract

BackgroundTuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (MTB). The recommended treatment for TB is based on the use of first-line drugs, including pyrazinamide (PZA). PZA is also a drug used in the treatment of multidrug-resistant TB (MDR-TB) because of its main effect against the latent stage. The main cause of resistance to PZA is mutations in the pncA gene, which compromise the activity of the encoded enzyme pyrazinamidase (PZAse), which hydrolyzes PZA into POA, the active antituberculosis molecule. The mechanism of action of PZA requires that POA is expelled from the bacterium by an efflux mechanism. After that, if the extracellular medium is sufficiently acidic, POA is protonated and returns to the cytosol, releasing the proton and repeating the cycle, resulting lethal to the bacteria. The efflux pump responsible for extruding the POA to the extracellular environment is not yet known. Mycobacterium smegmatis is naturally resistant to PZA and has a 900-fold faster POA efflux rate than MTB, and has the advantage to be a faster growing mycobacterium. MethodsIn the present study we have silenced the transcription of several genes encoding efflux pumps in M. smegmatis by CRISPRi (CRISPR interference). These genes (MSMEG_0250, MSMEG_3815, MSMEG_0241, MSMEG_5046 and MSMEG_0410) were homologous to efflux pump genes in MTB. POA efflux rate was measured, and a quantitative Waynes test was performed after silencing each gene. ResultsSilencing of MSMEG_0250, resulted in approximately 5-fold decrease in the POA efflux rate in M. smegmatis (P<0.0001). None of the other silenced genes showed a notable decrease in POA efflux rate.

Explore related subjects

molecular biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Quinones-Garcia, S., Gilman, R. H., Sheen, P., Zimic, M.. 2021-10-30. Silencing of an efflux pump coding gene decreases the efflux rate of pyrazinoic acid in Mycobacterium smegmatis. https://doi.org/10.1101/2021.10.29.466536

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Trans-branching of polyubiquitin chains orchestrates the DNA replication stress response

Polyubiquitin chain geometry dictates functional consequences of ubiquitylation. Although branched polyubiquitin chains are abundant in cells, little is known about their functions. Here we show that branching on the DNA replication factor PCNA, mediated by the ubiquitin-conjugating enzyme UBE2K and involving lysines 63 and 48 of ubiquitin, orchestrates the sequence of events in response to replication stress. By inducing VCP-dependent extraction of PCNA from chromatin, branching promotes re-priming of stalled forks and necessitates a BRCA1-dependent pathway of daughter-strand gap repair. Our study identifies hyper-accumulation of daughter-strand gaps as the mechanistic basis underlying the toxicity of inhibitors of the PCNA-specific isopeptidase, USP1, in BRCA1-deficient cells. Moreover, an unexpected preference of UBE2K to operate in trans suggests a general timing mechanism to organize hierarchies amongst ubiquitin signals.

molecular biology↗
bioRxiv2026

Impaired proteostasis is an early feature of the diabetic heart in humans and mice

Diabetes and obesity increase cardiac lipid levels leading to cardiomyopathy and heart failure. We hypothesized that intermittent fasting would reduce cardiac lipid levels. Surprisingly, intermittent fasting increased myocardial triglyceride content, but rescued mortality and attenuated cardiomyopathy in mice overexpressing cardiomyocyte acyl-CoA synthetase 1 (MHC-ACSL1). Lipid overload caused cardiomyocyte accumulation of polyubiquitinated protein aggregates containing desmin, a scaffolding intermediate filament protein, which intermittent fasting prevented. Furthermore, intermittent fasting reversed elevated myocardial C16:0 ceramide content, and knockdown of ceramide synthase CerS5 and CerS6 reduced palmitate-induced protein aggregation, highlighting a role for C16:0 ceramides in this pathology. Conversely, impairing aggrephagy with cardiomyocyte-specific p62 ablation induced heart failure in mice fed a high-fat diet, with paradoxically reduced cardiac lipid content. Crucially, non-failing diabetic human hearts also exhibited protein aggregate pathology. Taken together, these results demonstrate that impaired proteostasis characterizes cardiomyopathy from cardiac lipid overload and identify a promising new therapeutic target for this condition.

molecular biology↗
bioRxiv2026

Spatial profiling and neurovascular communication in the developing and adolescent cortex following prenatal alcohol exposure

Fetal alcohol spectrum disorders (FASD) constitute a wide range of developmental, cognitive, and behavioral impairments caused by prenatal alcohol exposure (PAE). Although neuronal and vascular consequences of PAE have been studied, how alcohol affects the cerebrovasculature within the framework of the neurovascular unit (NVU) across development remains poorly understood. At minimum, the NVU comprises neurons, astrocyte endfeet, and endothelial cells (ECs), which coordinate to maintain brain homeostasis. Here, we used the NanoString Digital Spatial Profiling platform to characterize spatial transcriptomic data from neurons, astrocytes, and ECs from PAE and saccharin (SAC) control cortices at embryonic day 18 (E18) and postnatal day 28 (P28). Differentially expressed genes were then used for Ingenuity Pathway Analysis (IPA) to identify altered biological pathways and perform comparison analyses across developmental time points, while CellChat was used to infer cell cell communication networks. We uncovered thousands of differentially expressed genes and numerous altered pathways and biological processes in PAE cortices across development. Both IPA and CellChat analyses implicated dysregulation of vascular and extracellular matrix (ECM) remodeling, cell adhesion, and neuroinflammatory signaling. CellChat further predicted the loss of several key bidirectional relationships and altered ligand-receptor interactions among neurovascular cell types at E18 and P28. Overall, these findings identify PAE associated alterations in neurovascular gene expression and intercellular signaling across development, providing potential mechanisms by which PAE may disrupt neurodevelopment.

molecular biology↗