Regulation of rns, a positive regulatory factor for pili of enterotoxigenic Escherichia coli

Abstract

Attachment of enterotoxigenic Escherichia coli to the human gut is considered an important early step in infection that leads to diarrhea. This attachment is mediated by pili, which belong to a limited number of serologically distinguishable types. Many of these pili require the product of rns, or a closely related gene, for their expression. We have located the major promoter for ins and found that although its sequence diverges significantly from a sigma-70 promoter consensus sequence, it is very strong. Transcription of rns is negatively regulated both at a region upstream of this promoter and at a region internal to the rns open reading frame.In addition, rns positively regulates its own transcription, probably by counteracting these two negative effects.

Growing Repertoire of AraC/XylS Activators

“…In addition to the pilinencoding operons, Rns activates expression of its own gene (14). Rns regulation of at least the cooB operon also involves repression by H-NS (32).…”

Transcriptional regulation of the macrophage‐induced gene (gspA) of Legionella pneumophila and phenotypic characterization of a null mutant

“…The plasmid pUC-4K was purchased from Pharmacia Biotech, and was the source of the Kan R gene used in generating the insertional mutation in gspA. The single-copy plasmid pEU730 is a spectinomycin-resistant plasmid containing a promoterless lacZ gene (Froehlich et al, 1994). The plasmid pTLP6 is a chloramphenicol-resistant plasmid containing the rpsL allele, which confers sensitivity to streptomycin (McClain et al, 1996;Arroyo et al, 1994).…”

“…The approx. 250 bp PCR product was purified from agarose gel and directionally cloned into the PacI-KpnI sites of the single-copy plasmid pEU730 (Froehlich et al, 1994), which places the promoterless lacZ gene immediately downstream under the control of the gspA promoter. The recombinant was designated pGSZ, and electroporated into L. pneumophila (Cianciotto and Fields, 1992).…”

Mutagenesis of the Rns regulator of enterotoxigenic Escherichia coli reveals roles for a linker sequence and two helix–turn–helix motifs

“…The Rns protein was originally identified as being required for the expression of CS1 and CS2 fimbriae of ETEC (Caron et al, 1989). Rns also positively autoregulates its gene expression (Froehlich et al, 1994) and activates the genes yiiS (unknown function) (Munson et al, 2002) and cexE, which encodes an uncharacterized extracytoplasmic protein . In addition, Rns can act as a negative regulator, repressing the expression of NlpA .…”