Iron Uptake in Salmonella typhimurium : Utilization of Exogenous Siderochromes as Iron Carriers

Abstract

Aerobic microorganisms have evolved a variety of siderochromes, special ligands which can dissolve insoluble ferric iron and facilitate its transport into the cell. We have found that enb mutants of Salmonella typhimurium blocked in the biosynthesis of enterobactin (its natural iron carrier) are able to utilize siderochromes of different types made by other microorganisms as iron carriers. The antibiotic albomycin 62 was used to select mutants defective in ferrichrome-mediated iron uptake. Twelve classes of albomycin-resistant mutants, named sid, were defined on the basis of their growth responses to other siderochromes. Most of these classes have genetic lesions in loci that are cotransduced with panC (represented at 9 min on the genetic map). The locus designated sid.J is cotransduced with enb, whereas sidK and sidL are linked with neither panC nor enb. Genetic and physiological data indicate that S. typhimurium has several transport systems of high specificity for a variety of siderochromes produced by other microorganisms.

The putative iron transport system SitABCD encoded on SPI1 is required for full virulence of Salmonella typhimurium

“…S. typhimurium synthesizes the siderophore enterobactin for iron(III) uptake (Luckey et al, 1972). Two studies a.…”

“…However, the primary iron source in the host is not clear. As noted, S. typhimurium are adept at using a large variety of metabolites and siderophores produced by a number of organisms for iron uptake (Luckey et al, 1972;Earhart, 1996;Reissbrodt et al, 1997). Perhaps a siderophore or siderophore-like substance is the primary source of iron in the host.…”

“…Some strains of S. typhimurium can also produce aerobactin, which is usually plasmid encoded (Reissbrodt and Rabsch, 1988). In addition, S. typhimurium can transport a variety of siderophores, including ferrichrome, ferrioxamines, pyoverdines, myxochelins and coprogen, that are produced by other organisms (Luckey et al, 1972;Kingsley et al, 1995). Certain metabolites, such as 2,3-dihydroxybenzoic acid and dihydroxybenoylserines, can also act as siderophores (Earhart, 1996).…”

Induction of an outer membrane protein of 78 kDa in Vibrio vulnificus cultured in the presence of desferrioxamine B under iron-limiting conditions

“…Since in vivo growth of bacteria depends upon their ability to acquire iron from the host, the siderophore-mediated iron uptake has been suggested as one of the factors determining bacterial virulence [2]. In addition to their endogenous siderophores, some bacterial species such as Escherichia coli [2], Salmonella typhimurium [3], Pseudomonas aeru-ginosa [4], Yersinia enterocolitica [5], and Neisseria gonorrhoeae [6] are able to utilize exogenous siderophores produced by other bacteria or fungi. Bacteria do not solely utilize the cognate siderophores, whether or not they produce their own siderophores.…”

Characterization of the catecholate indicator strain S. typhimurium TA2700 as an ent fhuC double mutant

“…A sidA mu-tant of S. typhimurium (TA2700), unable to use the diverse hydroxamate siderophores (e.g. coprogen, rhodotorulic acid, ferrioxamine and ferrichrome) was isolated [3]. Using siderophore-pattern analysis, this strain proved to be a good indicator strain for enterobactin and other selected catecholate siderophores [4^6].…”