Premium
ATP reduction by MgtC and Mg 2+ homeostasis by MgtA and MgtB enables Salmonella to accumulate RpoS upon low cytoplasmic Mg 2+ stress
Author(s) -
Park Myungseo,
Nam Daesil,
Kweon DaeHyuk,
Shin Dongwoo
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.14105
Subject(s) - rpos , biology , salmonella enterica , sigma factor , escherichia coli , salmonella , gene expression , microbiology and biotechnology , cytoplasm , bacteria , gene , biochemistry , rna polymerase , genetics , promoter
Summary RpoS is one of several alternative sigma factors known to alter gene expression profiles by RpoS‐associated RNA polymerase in response to a variety of stresses. The enteric bacteria Salmonella enterica and Escherichia coli accumulate RpoS under low Mg 2+ concentrations via a common mechanism in which the PhoP regulator activates expression of antiadaptor proteins that, by sequestering the adaptor RssB, prevent RpoS degradation by the protease ClpXP. Here, we demonstrate that this genetic program alone does not fully support RpoS accumulation when cytoplasmic Mg 2+ concentration drops to levels that impair protein synthesis. Under these circumstances, only S. enterica continues RpoS accumulation in a manner dependent on other PhoP‐activated programs (i.e. ATP reduction by the MgtC protein and Mg 2+ import by the MgtA and MgtB transporters) that maintain translation homeostasis. Moreover, we provide evidence that the mgtC gene, which is present in S. enterica but not in E. coli , is responsible for the differences in RpoS accumulation between these two bacterial species. Our results suggest that bacteria possess a mechanism to control RpoS accumulation responding to cytoplasmic Mg 2+ levels, the difference of which causes distinct RpoS accumulation in closely related bacterial species.