Mycobacterial MenG: Partial Purification, Characterization, and Inhibition.

Menaquinone (MK) is an essential component of the electron transport chain (ETC) in the gram-variable and many Gram-positive pathogens. Three genes in the genome were annotated as methyltransferases involved in lipoquinone synthesis in mycobacteria. Heterologous expression of complemented an (the quinone -methyltransferase involved in ubiquinone and menaquinone synthesis) deletion in and expression in a wild-type strain increased quinone -methyltransferase specific activity by threefold.

Characterization of MenA (isoprenyl diphosphate:1,4-dihydroxy-2-naphthoate isoprenyltransferase) from Mycobacterium tuberculosis.

The menaquinone biosynthetic pathway presents a promising drug target against Mycobacterium tuberculosis and potentially other Gram-positive pathogens. In the present study, the essentiality, steady state kinetics of MenA from M. tuberculosis and the mechanism of MenA inhibition by Ro 48-8071 were characterized.

Comparative evaluation of 15% ethylenediamine tetra-acetic acid plus cetavlon and 5% chlorine dioxide in removal of smear layer: A scanning electron microscope study.

Aims: The purpose of this study was to compare the efficacy of smear layer removal by 5% chlorine dioxide and 15% Ethylenediamine Tetra-Acetic Acid plus Cetavlon (EDTAC) from the human root canal dentin.

Materials And Methods: Fifty single rooted human mandibular anterior teeth were divided into two groups of 20 teeth each and control group of 10 teeth. The root canals were prepared till F3 protaper and initially irrigated with 2% Sodium hypochlorite followed by 1 min irrigation with 15% EDTAC or 5% Chlorine dioxide respectively.

A phosphorylated pseudokinase complex controls cell wall synthesis in mycobacteria.

Prokaryotic cell wall biosynthesis is coordinated with cell growth and division, but the mechanisms regulating this dynamic process remain obscure. Here, we describe a phosphorylation-dependent regulatory complex that controls peptidoglycan (PG) biosynthesis in Mycobacterium tuberculosis. We found that PknB, a PG-responsive Ser-Thr protein kinase (STPK), initiates complex assembly by phosphorylating a kinase-like domain in the essential PG biosynthetic protein, MviN.

Lipoarabinomannan localization and abundance during growth of Mycobacterium smegmatis.

Lipoarabinomannan (LAM) is a structurally heterogeneous amphipathic lipoglycan present in Mycobacterium spp. and other actinomycetes, which constitutes a major component of the cell wall and exhibits a wide spectrum of immunomodulatory effects. Analysis of Mycobacterium smegmatis subcellular fractions and spheroplasts showed that LAM and lipomannan (LM) were primarily found in a cell wall-enriched subcellular fraction and correlated with the presence (or absence) of the mycolic acids in spheroplast preparations, suggesting that LAM and LM are primarily associated with the putative outer membrane of mycobacteria.

DosS responds to a reduced electron transport system to induce the Mycobacterium tuberculosis DosR regulon.

The DosR regulon in Mycobacterium tuberculosis is involved in respiration-limiting conditions, its induction is controlled by two histidine kinases, DosS and DosT, and recent experimental evidence indicates DosS senses either molecular oxygen or a redox change. Under aerobic conditions, induction of the DosR regulon by DosS, but not DosT, was observed after the addition of ascorbate, a powerful cytochrome c reductant, demonstrating that DosS responds to a redox signal even in the presence of high oxygen tension. During hypoxic conditions, regulon induction was attenuated by treatment with compounds that occluded electron flow into the menaquinone pool or decreased the size of the menaquinone pool itself.

Menaquinone synthesis is critical for maintaining mycobacterial viability during exponential growth and recovery from non-replicating persistence.

Understanding the basis of bacterial persistence in latent infections is critical for eradication of tuberculosis. Analysis of Mycobacterium tuberculosis mRNA expression in an in vitro model of non-replicating persistence indicated that the bacilli require electron transport chain components and ATP synthesis for survival. Additionally, low microM concentrations of aminoalkoxydiphenylmethane derivatives inhibited both the aerobic growth and survival of non-replicating, persistent M.

1-Deoxy-D-xylulose 5-phosphate reductoisomerase (IspC) from Mycobacterium tuberculosis: towards understanding mycobacterial resistance to fosmidomycin.

1-Deoxy-d-xylulose 5-phosphate reductoisomerase (IspC) catalyzes the first committed step in the mevalonate-independent isopentenyl diphosphate biosynthetic pathway and is a potential drug target in some pathogenic bacteria. The antibiotic fosmidomycin has been shown to inhibit IspC in a number of organisms and is active against most gram-negative bacteria but not gram positives, including Mycobacterium tuberculosis, even though the mevalonate-independent pathway is the sole isopentenyl diphosphate biosynthetic pathway in this organism. Therefore, the enzymatic properties of recombinant IspC from M.

Identification of a novel class of omega,E,E-farnesyl diphosphate synthase from Mycobacterium tuberculosis.

We have identified an omega,E,E-farnesyl diphosphate (omega,E,E-FPP) synthase, encoded by the open reading frame Rv3398c, from Mycobacterium tuberculosis that is unique among reported FPP synthases in that it does not contain the type I (eukaryotic) or the type II (eubacterial) omega,E,E-FPP synthase signature motif. Instead, it has a structural motif similar to that of the type I geranylgeranyl diphosphate synthase found in Archaea. Thus, the enzyme represents a novel class of omega,E,E-FPP synthase.