Hfq-dependent regulation of OmpA synthesis is mediated by an antisense RNA

AUTOR(ES)

Udekwu, Klas I.

FONTE

Cold Spring Harbor Laboratory Press

RESUMO

This paper shows that the small RNA MicA (previously SraD) is an antisense regulator of ompA in Escherichia coli. MicA accumulates upon entry into stationary phase and down-regulates the level of ompA mRNA. Regulation of ompA (outer membrane protein A), previously attributed to Hfq/mRNA binding, is lost upon deletion of the micA gene, whereas overexpression of MicA inhibits the synthesis of OmpA. In vitro, MicA binds to the ompA mRNA leader. Enzymatic and chemical probing was used to map the structures of MicA, the ompA mRNA leader, and the complex formed upon binding. MicA binding generates a footprint across the ompA Shine-Dalgarno sequence, consistent with a 12 + 4 base-pair interaction, which is additionally supported by the effect of mutations in vivo and by bioinformatics analysis of enterobacterial micA/ompA homolog sequences. MicA is conserved in many enterobacteria, as is its ompA target site. In vitro toeprinting confirmed that binding of MicA specifically interferes with ribosome binding. We propose that MicA, when present at high levels, blocks ribosome binding at the ompA translation start site, which—in line with previous work—secondarily facilitates RNase E cleavage and subsequent mRNA decay. MicA requires the presence of the Hfq protein, although the mechanistic basis for this remains unclear.

Documentos Relacionados

• Constitutive Activation of the Escherichia coli Pho Regulon Upregulates rpoS Translation in an Hfq-Dependent Fashion
• Hfq (HF1) stimulates ompA mRNA decay by interfering with ribosome binding
• Host factor I, Hfq, binds to Escherichia coli ompA mRNA in a growth rate-dependent fashion and regulates its stability
• Effect of OmpA signal peptide mutations on OmpA secretion, synthesis, and assembly.
• Regulation of the OmpA outer membrane protein of Escherichia coli.