Iron-responsive genetic regulation in Campylobacter jejuni: cloning and characterization of a fur homolog

Abstract

The Fur protein of Escherichia coli represses transcription from Fur-responsive genes in an iron-dependent manner. We have demonstrated a Fur-like iron-responsive genetic regulatory activity operating in Campylobacter jejuni by using a chloramphenicol acetyl transferase reporter gene separated from its promoter by a synthetic Fur-responsive operator. A fur-like gene has been cloned from C. jejuni by partial functional complementation of an E. coli fur mutation. Sequence analysis has shown that, at the amino acid level, the C. jejuni Fur protein is 35% identical with its E. coli counterpart.

Metalloregulation in vitro of the aerobactin promoter of Escherichia coli by the Fur (ferric uptake regulation) protein

“…In addition, there are some indications that Fur may act positively on other promoters (Niederhoffer et al, 1990;Hall and Foster, 1996). Highly conserved homologues of the fur gene of E. coli have been cloned and characterized from diverse Gramnegative bacteria (Staggs and Perry, 1991;Litwin and Calderwood, 1993b;Prince et al, 1993;Thomas and Sparling, 1994;Wooldridge et al, 1994), which suggests that the molecular mechanism involved in the regulation of iron acquisition could be shared by many microorganisms. The simplest of all iron-regulated promoters is that found at the 5Ј region of the aerobactin operon, which determines the biosynthesis of this siderophore in many virulent enterobacterial strains.…”

Pathogenesis of Enteric Infection by Campylobacter

“…Thus, an iron-responsive regulatory circuit similar to the Fur system probably regulates a subset of virulence-associated genes in C. jejuni. Wooldridge et al (1994) and now others (Chan et al, 1995) have cloned the fur gene from C . jejuni.…”

Virulence of Campylobacter species: A molecular genetic approach

“…The degree of dissimilarity of the C. jejuni Fur protein with respect to its E. coli counterpart is reflected both antigenically, by its lack of reactivity in Western blots, and functionally, by the low level of repression of an E. coli furregulated promoter compared to that afforded by the E. coli Fur protein. 162 If C. jejuni Fur-like protein is truly the major iron-dependent regulator in this organism, its recognition sequence, as well as the repressor itself, may have diverged significantly between the two species. Since Fur and Fur-like repressors are known to regulate some virulence determinant genes in other bacteria, it is likely that the Fur-like repressor protein also regulates a subset of C. jejuni genes with a role in pathogenesis.…”