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High‐level, constitutive expression of the mgtC gene confers increased thermotolerance on Salmonella enterica serovar Typhimurium
Author(s) -
Gall Aaron R.,
Hegarty Annie E.,
Datsenko Kirill A.,
Westerman Richard P.,
SanMiguel Phillip,
Csonka Laszlo N.
Publication year - 2018
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.13988
Subject(s) - biology , salmonella enterica , salmonella , serotype , gene , microbiology and biotechnology , enterobacteriaceae , gene expression , genetics , bacteria , escherichia coli
Summary We found that mutations that increased the transcription of the mgtCBR (Mg 2+ transport‐related) operon conferred increased thermotolerance on this organism. The 5′ leader of the mgtCBR mRNA contains two short open reading frames (ORFs), mgtM and mgtP , whose translation regulates the expression of the mgtCBR operon by a mechanism that is similar to attenuation in amino acid biosynthetic operons. We obtained two types of mutations that resulted in elevated transcription of the operon: defects in the mgtM ribosome‐binding site, impairing the translation of this ORF and deletions encompassing the stop codon of mgtM that extend the translation of this ORF across a downstream Rho termination site. These mgtM mutations give further insights into the mechanism of the transcriptional control of the mgtCBR operon that we discuss in this work. We show that the increased thermotolerance requires elevated expression of the mgtC gene, but functional mgtB and mgtR , which respectively encode an Mg 2+ transporter and a regulatory protein, are dispensable for this response. MgtC has been shown to have complex functions, including a requirement for virulence, flagella‐independent motility and synthesis of cellulose and we now found that it has a role in the regulation of thermotolerance.