Mutations Affecting Iron Transport in Escherichia coli

Abstract

A mutant of Escherichia coli K-12 unable to form an essential component of the enterochelin-dependent iron transport system has been isolated. This strain carries a mutation in a gene designated fep, mapping close to two genes, entA and entD, concerned with enterochelin synthesis. Strain AN102, which carries the fepallele, accumulates large quantities of enterochelin and gives a growth response to sodium citrate. The cytochrome b1 and total iron content, and the measurement of the uptake of a5FeE+, indicate an impairment of the enterochelin-dependent iron transport system. The growth response to sodium citrate is related to the presence, in strain AN102, of an inducible citrate-dependent iron transport system. MATERIALS AND METHODS Chemicals. Chemicals used were of the highest purity obtainable and, unless otherwise specified, were not further purified. "5Fe3+ was obtained as a carrierfree solution of FeCI3 in 0.1 M HCI from The Radiochemical Centre, Amersham, England. Enterochelin and 2, 3-dihydroxy-N-benzoylserine were isolated from culture supernatants as described previously (9; O'Brien and Gibson, in press). Bacterial strains. All the strains used were derived from E. coli K-12 and are listed in Table 1. Culture media. The medium used for growth of cells, except those used in iron-uptake experiments, was double-strength medium 56 described by Monod et al. (8). To the sterilized mineral salts base was 219

Iron uptake in colicin B-resistant mutants of Escherichia coli K-12

“…The aroE cbt strain P1553 is very similar to the aroB fep mutant described by Cox et al (4,21). Both cbt and feb mutations block the active uptake of ferri-enterochelin but do not affect ferrichrome-, rhodotorulic acid-, or citrate-mediated iron uptake.…”

“…coli in the absence of freely available iron (7). Specific iron uptake systems have been identified for enterochelin- (4); for ferrichrome- (11,28), a siderochrome produced by Ascomycetes, Basidiomycetes, and Fungi Imperfecti (20); and for citrate-mediated iron uptake (6) in E. coli K-12.…”

Concerted loop motion triggers induced fit of FepA to ferric enterobactin

“…We purified enterobactin from E. coli strain AN102 (Cox et al, 1970), prepared its ferric complex (Wayne and Neilands, 1975; Klebba et al, 1982), and stored the ferric siderophore on ice. When FeEnt solutions became oxidized or degraded, we repurified the authentic metal complex by chromatography on a Sephadex LH-20 (Wayne and Neilands, 1975) and determined its concentration from its absorbance at 495 nm.…”

Competence ofCorynebacterium glutamicumas a host for the production of type I polyketides

“…Analogous to PKS systems, both EntB and EntF are phosphopantetheinylated by a PPTase named EntD (UniProt ID P19925) encoded in the enterobactin locus (Gehring et al, 1997;Lambalot et al, 1996). While inactivation of entD abolishes production of enterobactin in E. coli (Cox et al, 1970), this phenotype can be rescued by complementation with an exogenous PPTase (Barekzi et al, 2004). To test whether PptACg is similarly capable to act as a substitute for the enterobactin PPTase, an entD mutation was introduced into the E. coli strain BW25113, which was previously reported as enterobactin producer (Ma and Payne, 2012).…”