Biology subjects

M, B.

Publications and source records attributed to M, B..

4 recordsLinked to original sources

bioRxiv2023

Outer membrane proteins in Mycobacterium tuberculosis and its potential role in small molecule permeation

Increased resistance to current anti-mycobacterial and a potential bias towards relatively hydrophobic chemical entities highlight an urgent need to understand how current anti-TB drugs enter the tubercle bacilli. While inner membrane proteins are well-studied, how small molecules cross the impenetrable outer membrane remains unknown. Here we employed mass spectrometry-based proteomics to show that octyl-{beta}-glucopyranoside selectively extracts the outer membrane proteins of Mycobacterium tuberculosis. Differentially expressed proteins between nutrient replete and depleted conditions were enriched to identify proteins involved in nutrient uptake. We demonstrate cell surface localization of seven new proteins using immunofluorescence and show that overexpression of the proteins LpqY and ProX leads to hypersensitivity towards streptomycin, while expression of SubI, FecB2, and Rv0999 exhibited higher membrane permeability, assessed through EtBr accumulation assay. Further, proton NMR metabolomics suggests the role of four outer membrane proteins in glycerol uptake. This study identifies several outer membrane proteins that are involved in the permeation of small hydrophilic molecules and are potential targets for enhancing uptake and efficacy of anti-TB drugs.

microbiology↗

bioRxiv2022

Trends in Arabidopsis Research post genome sequencing- A Scientometric study

1.Arabidopsis thaliana, a model plant, is intensively researched because of the intrinsic advantages associated with its life cycle, genetics, and other characteristics. In the present study, we analysed the publication data of research work done on A. thaliana during 2001-2020, a period when the whole genome sequence of the plant was available to the researchers. The current meta-analysis showed that 31965 research papers were published globally on Arabidopsis during the study period. The USA topped the countries with the maximum share of publications (28.97%), followed by China, Japan, and West European countries. The analysis showed a temporal shift in the number of publications from different countries and their research focus. After 2013, the research output from China was higher than that from the USA, and there was a shift in focus from developmental biology to stress-related topics. Plant Physiology journal carried the most research work (2490 publications) on Arabidopsis, which was followed by Plant Cell (2376), the Plant Journal (2260) and the Journal of Experimental Botany (1121). However, there was a progressive decline in the publication in these journals, and a shift was evident in favour of open access journals like Frontiers in Plant Science. The publication and citation numbers also show ongoing Arabidopsis researchs relevance to plant sciences, particularly curiosity-driven and discovery-based science. This article delves into the patterns in the prominence of research areas, ideas and foci for the future Arabidopsis research roadmap.

plant biology↗

bioRxiv2020

Transcription repressor protein ZBTB25 interacts with HDAC1 in macrophages infected with Mycobacterium tuberculosis, and its inhibition leads to autophagy and killing of the intracellular pathogen

Downregulation of host gene expression is one of the key strategies adopted by intracellular pathogens such as Mycobacterium tuberculosis (MTB) for their survival and subsequent pathogenesis. In a previous study, we have shown that HDAC1 levels go up in macrophages infected with MTB and it hypoacetylates histone H3 at the promoter of IL-12B gene leading to its downregulation. Here we show that after infection with MTB, the levels of the phosphorylated form of HDAC1 increase significantly in macrophages. Employing immunoprecipitation and LC-MS/MS, we found transcriptional repressor protein ZBTB25 associates with HDAC1 silencing complex along with transcriptional corepressor Sin3a. By chromatin immunoprecipitation and PCR analyses, we found that phosphorylated HDAC1, Sin3a, and ZBTB25 are recruited to the promoter of IL-12B to downregulate its expression in infected macrophages. Knocking down of ZBTB25 enhanced release of IL-12p40 from infected macrophages. Interestingly, the treatment of infected macrophages with CI994 (inhibitor of HDAC1) or dithiopyridine (inhibitor of ZBTB25) promoted the colocalization of LC3 (microtubule-associated protein 1A/1B-light chain 3, a marker for autophagy) and MTB in autophagosomes. Induction of autophagy resulted in the killing of intracellular MTB. Enhanced phosphorylation of JAK2 and STAT4 was observed in macrophages upon CI994 and dithiopyridine treatment, and inhibition of JAK2/STAT4 negated the killing of intracellular mycobacteria suggesting a possible role of these proteins in the autophagy-mediated killing of intracellular MTB.

microbiology↗

bioRxiv2020

Acetylation of isoniazid - a novel mechanism of isoniazid resistance in Mycobacterium tuberculosis

Isoniazid (INH), one of the first-line drugs used for the treatment of tuberculosis, is a pro-drug which is converted into its active form by the intracellular KatG enzyme of Mycobacterium tuberculosis. The activated drug hinders cell wall biosynthesis by inhibiting InhA protein. INH resistant strains of M. tuberculosis usually have mutations in katG, inhA, ahpC, kasA, and ndh genes. However, INH resistant strains which do not have mutations in any of these genes are reported, suggesting that these strains may adopt some other mechanism to become resistant to INH. In the present study we characterized Rv2170, a putative acetyltransferase in M. tuberculosis, to elucidate its role in inactivating isoniazid. The purified recombinant protein was able to catalyze transfer of acetyl group to INH from acetyl CoA. HPLC and LC-MS analyses showed that following acetylation by Rv2170, INH is broken down into isonicotinic acid and acetylhydrazine. Drug susceptibility assay and confocal analysis showed that M. smegmatis, which is susceptible to INH, is not inhibited by INH acetylated with Rv2170. Recombinant M. smegmatis and M. tuberculosis H37Ra overexpressing Rv2170 were found to be resistant to INH at minimum inhibitory concentrations that inhibited wildtype strains. In addition, intracellular M. tuberculosis H37Ra overexpressing Rv2170 survived better in macrophages when treated with INH. Our results strongly indicate that Rv2170 acetylates INH, and this could be one of the strategies adopted by at least some M. tuberculosis strains to overcome INH toxicity.

biochemistry↗