Affiliation:
1. Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
Abstract
ABSTRACT
A previous bioinformatics-based search for small RNAs in
Escherichia coli
identified a novel RNA named IS183. The gene encoding this small RNA is located between and on the opposite strand of genes encoding two transcriptional regulators of the acid response,
gadX
(
yhiX
) and
gadW
(
yhiW
). Given that IS183 is encoded in the
gad
gene cluster and because of its role in regulating acid response genes reported here, this RNA has been renamed GadY. We show that GadY exists in three forms, a long form consisting of 105 nucleotides and two processed forms, consisting of 90 and 59 nucleotides. The expression of this small RNA is highly induced during stationary phase in a manner that is dependent on the alternative sigma factor σ
S
. Overexpression of the three GadY RNA forms resulted in increased levels of the mRNA encoding the GadX transcriptional activator, which in turn caused increased levels of the GadA and GadB glutamate decarboxylases. A promoter mutation which abolished
gadY
expression resulted in a reduction in the amount of
gadX
mRNA during stationary phase. The
gadY
gene was shown to overlap the 3′ end of the
gadX
gene, and this overlap region was found to be necessary for the GadY-dependent accumulation of
gadX
mRNA. We suggest that during stationary phase, GadY forms base pairs with the 3′-untranslated region of the
gadX
mRNA and confers increased stability, allowing for
gadX
mRNA accumulation and the increased expression of downstream acid resistance genes.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
294 articles.
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