Novel mechanism of Escherichia coli porin regulation

Maria Castillo-Keller, Phu Vuong, Rajeev Misra

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

A novel mechanism of Escherichia coli porin regulation was discovered from multicopy suppressors that permitted growth of cells expressing a mutant OmpC protein in the absence of DegP. Analyses of two suppressors showed that both substantially lowered OmpC expression. Suppression activities were confined to a short DNA sequence, which we designated ipeX for inhibition of porin expression, and to DNA containing a 3′-truncated ompR gene. The major effect of ipeX on ompC expression was exerted posttranscriptionally, whereas the truncated OmpR protein reduced ompC transcription. ipeX was localized within an untranslated region of 247 base pairs between the stop codon of nmpC-a remnant porin gene from the cryptic phage qsr′ (DLP12) genome-and its predicted Rho-independent transcriptional terminator. Interestingly, another pro-phage, PA-2, which encodes a porin similar to NmpC, known as Lc, has sequences downstream from lc identical to that of ipeX. PA-2 lysogenization leads to Lc expression and OmpC inhibition. Our data show that the synthesis of the lc transcript, whose 3′ end contains the corresponding ipeX sequence, inhibits OmpC expression. Overexpression of ipeX RNA inhibited both OmpC and OmpF expression but not that of OmpA. ompC-phoA chimeric gene constructs revealed a 248-bp untranslated region of ompC required for ipeX-mediated inhibition. However, no sequence complementarity was found between ipeX and this region of ompC, indicating that inhibition may not involve simple base pairing between the two RNA molecules. The effect of ipeX on ompC, but not on ompF, was independent of the RNA chaperone Hfq.

Original languageEnglish (US)
Pages (from-to)576-586
Number of pages11
JournalJournal of Bacteriology
Volume188
Issue number2
DOIs
StatePublished - Jan 2006

Fingerprint

Porins
Escherichia coli
Untranslated Regions
RNA
Base Pairing
Bacteriophages
Genes
Terminator Codon
Mutant Proteins
Genome
DNA
Growth
OmpC protein

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Immunology

Cite this

Novel mechanism of Escherichia coli porin regulation. / Castillo-Keller, Maria; Vuong, Phu; Misra, Rajeev.

In: Journal of Bacteriology, Vol. 188, No. 2, 01.2006, p. 576-586.

Research output: Contribution to journalArticle

Castillo-Keller, Maria ; Vuong, Phu ; Misra, Rajeev. / Novel mechanism of Escherichia coli porin regulation. In: Journal of Bacteriology. 2006 ; Vol. 188, No. 2. pp. 576-586.
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