Biology subjects

Mukamolova, G.

Publications and source records attributed to Mukamolova, G..

4 recordsLinked to original sources

bioRxiv2024

The RpfB switch is a novel B12-sensing riboswitch regulating (non-replicating) persistence in Mycobacterium tuberculosis.

Riboswitches are metabolite-sensing RNA elements that control a wide range of genes in bacteria. Most riboswitches identified to date are broadly conserved and control genes that are directly involved in the transport or biosynthesis of their cognate ligands. However, a minority of switches are restricted to a few species and in addition may bind less obvious ligands. One such switch controls the expression of the Mycobacterium tuberculosis rpfB operon, which is critical for resuscitation of dormant bacteria, ribosome maturation and reactivation of latent tuberculosis infection. The switch is restricted to pathogenic mycobacteria and until now, its ligand was unknown. However, in the current study, we identify the ligand as cobalamin or vitamin B12. Using in-line probing, we show that vitamin B12 binds directly to the riboswitch RNA, and we predict a structure based on the cleavage pattern. Moreover, we show that B12 suppresses the expression of an rpfB-lacZ reporter fusion and crucially, that B12 suppresses resuscitation of M. tuberculosis from a state of non-replicating persistence. These findings demonstrate a pivotal role of crosstalk between a host-derived metabolite and a pathogen riboswitch in controlling M. tuberculosis persistence with potential for improved interventions.

molecular biology↗

bioRxiv2021

A Mycobacterium tuberculosis effector targets mitochondrion, controls energy metabolism and limits cytochrome c exit.

Host metabolism reprogramming is a key feature of Mycobacterium tuberculosis (Mtb) infection that enables the survival of this pathogen within phagocytic cells and modulates the immune response facilitating the spread of the tuberculosis disease. Here, we demonstrate that a previously uncharacterized secreted protein from Mtb, Rv1813c manipulates the host metabolism by targeting mitochondria. When expressed in eukaryotic cells, the protein is delivered to the mitochondrial intermembrane space and promotes the enhancement of host ATP production by boosting the oxidative phosphorylation metabolic pathway. Furthermore, the release of cytochrome c from mitochondria, an early apoptotic event in response to short-term oxidative stress, is delayed in Rv1813c expressing cells. This study reveals a novel class of mitochondria targeting effectors from Mtb which might participate in host cells metabolic reprogramming and apoptosis control during Mtb infections.

microbiology↗

bioRxiv2020

A virulence associated siderophore importer causes antimicrobial efflux in Klebsiella pneumoniae

The accessory genome of many pathogenic bacteria includes ABC transporters that scavenge metal by siderophore uptake and ABC transporters that contribute to antimicrobial resistance by multidrug efflux. There are mechanistic and recently recognised structural similarities between siderophore importer proteins and efflux pumps. Here we investigated the influence of siderophore importer YbtPQ on antimicrobial resistance of Klebsiella pneumoniae. YbtPQ is encoded in the yersiniabactin cluster in a prevalent mobile genetic element ICEKp, and is also common in pathogenicity islands of Escherichia coli and Yersinia species, where yersiniabactin enhances virulence. Deletion of ICEKp increased the sensitivity of K. pneumoniae to all antimicrobials tested. The mechanism was dependent on the yersiniabactin importer YbtPQ and involved antimicrobial efflux, since it was affected by the inhibitor reserpine. The element ICEKp is naturally highly mobile, indeed the accessory genome of K. pneumoniae is recognised as a reservoir of genes for the emergence of hospital outbreak strains and for transfer to other Gram-negative pathogens. Introduction of ICEKp, or a plasmid encoding YbtPQ, to E. coli decreased its sensitivity to a broad range of antimicrobials. Thus, a confirmed siderophore importer, on a rapidly evolving and highly mobile element capable of interspecies transfer, may have a secondary function exporting antimicrobials.

microbiology↗

bioRxiv2018

Mycobacteria recycle their peptidoglycan via a novel pathway which influences antimicrobial resistance and limits proliferation in macrophages.

Growth and division by most bacteria requires remodeling and cleavage of their cell wall. A byproduct of this process is the generation of free peptidoglycan (PG) fragments known as muropeptides. These muropeptides are recycled in many model organisms, where the bacteria can harness their unique nature as a signal for cell wall damage. These molecules also serve as important signals for hosts where binding to specific receptors reports on the presence of intracellular bacteria. Despite this critical role for muropeptides, it has long been thought that pathogenic mycobacteria such as Mycobacterium tuberculosis do not recycle their PG. Herein we show for the first time that M. tuberculosis and Mycobacterium bovis BCG are able to recycle components of their PG. We demonstrate that the core-mycobacterial gene lpqI, encodes an authentic NagZ {beta}-N-acetylglucosaminidase and that it is essential for PG-derived amino sugar recycling via an unusual pathway. By characterizing an M. bovis BCG strain lacking lpqI we are also able to show that stem-peptide recycling proceeds independent of amino sugar recovery and loss of lpqI leads to antimicrobial resistance in vitro. Together these data provide a critical first step in understanding how mycobacteria recycle their peptidoglycan.

microbiology↗