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Overexpression of an antisense RNA, ArrS, increases the acid resistance of Escherichia coli

2014; Microbiology Society; Volume: 160; Issue: 5 Linguagem: Inglês

10.1099/mic.0.075994-0

1465-2080

Toshiko Aiso, Shigeru Kamiya, Hideo Yonezawa, Shinobu Gamou,

Bacteriophages and microbial interactions

The antisense RNA ArrS is complementary to a sequence in the 5′ untranslated region of the gadE T3 mRNA, the largest transcript of gadE , which encodes a transcriptional activator of the glutamate-dependent acid resistance system in Escherichia coli . Expression of arrS is strongly induced during the stationary growth phase, particularly under acidic conditions, and transcription is dependent on σ S and GadE. The aim of the present study was to clarify the role of ArrS in controlling gadE expression by overexpressing arrS in E. coli . The results showed a marked increase in the survival of arrS -overexpressing cells at 2 h after a shift to pH 2.5. This was accompanied by increased expression of gadA , gadBC and gadE . The level of gadE T3 mRNA decreased markedly in response to arrS overexpression, and was accompanied by a marked increase in gadE mRNA T2. T2 mRNA had a monophosphorylated 5′ terminus, which is usually found in cleaved mRNAs, and no T2 mRNA was observed in an RNase III-deficient cell strain. In addition, T2 mRNA was not generated by a P3-deleted gadE – luc translational fusion. These results suggest strongly that T2 mRNA is generated via the processing of T3 mRNA. Moreover, the T2 mRNA, which was abundant in arrS -overexpressing cells, was more stable than T3 mRNA in non-overexpressing cells. These results suggest that overexpression of ArrS positively regulates gadE expression in a post-transcriptional manner.