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Author Rensburg, Elizabeth J. Van ♦ Osman, Ayman G. ♦ Cholo, Moloko C. ♦ Anderson, Ronald
Source Directory of Open Access Journals (DOAJ)
Content type Text
Publisher Hindawi Limited
File Format HTM / HTML
Date Created 2015-09-10
Copyright Year ©2015
Language English
Subject Domain (in LCC) R
Subject Keyword Medicine
Abstract Two potassium (K+)-uptake systems, Trk and Kdp, are operative in Mycobacterium tuberculosis (Mtb), but the environmental factors triggering their expression have not been determined. The current study has evaluated the expression of these genes in the Mtb wild-type and a trk-gene knockout strain at various stages of logarithmic growth in relation to extracellular K+ concentrations and pH. In both strains, mRNA levels of the K+-uptake encoding genes were relatively low compared to those of the housekeeping gene, sigA, at the early- and mid-log phases, increasing during late-log. Increased gene expression coincided with decreased K+ uptake in the context of a drop in extracellular pH and sustained high extracellular K+ concentrations. In an additional series of experiments, the pH of the growth medium was manipulated by the addition of 1N HCl/NaOH. Decreasing the pH resulted in reductions in both membrane potential and K+ uptake in the setting of significant induction of genes encoding both K+ transporters. These observations are consistent with induction of the genes encoding the active K+ transporters of Mtb as a strategy to compensate for loss of membrane potential-driven uptake of K+ at low extracellular pH. Induction of these genes may promote survival in the acidic environments of the intracellular vacuole and granuloma.
ISSN 23146133
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG ♦ Career/Technical Study
Learning Resource Type Article
Publisher Date 2015-01-01
e-ISSN 23146133
Journal BioMed Research International
Volume Number 2015


Source: Directory of Open Access Journals (DOAJ)