Staphyloferrin A: a structurally new siderophore from staphylococci

Publisher Website
Google Scholar
Abstract
Two ferric ion‐binding compounds, designated staphyloferrin A and B, were detected in the culture filtrates of staphylococci‐grown under iron‐deficient conditions. Staphyloferrin A was isolated from cultures ofStaphylococcus hyicusDSM 20459. The structural elucidation of this highly hydrophilic, acid‐labile compound revealed a novel siderophore,N2,N5‐di‐(l‐oxo‐3‐hydroxy‐3,4‐dicarboxybutyl)‐D‐ornithine, which consists of one ornithine and two citric acid residues linked by two amide bonds. The two citric acid components of staphyloferrin A provide two tridentate pendant ligands, comprising of a β‐hydroxy, β‐carboxy‐substituted carboxylic acid derivative, for octahedral metal chelation. The CD spectrum of the staphyloferrin A ferric complex indicates a predominant A configuration about the ferric ion center. The uptake of ferric staphyloferrin A byS. hyicusobeys Michaelis‐Menten kinetics (Km= 0.246 μM;vmax= 82 pmol · mg−1· min−1), indicating active transport of this siderophore. The staphyloferrin A transport system is different from that of the ferrioxamines as shown by an antagonism test. Production of staphyloferrin A is strongly iron‐dependent and is stimulated by supplementation of the medium with either D‐ or L‐ornithine. DL‐[5‐14C]ornithine was incorporated into staphyloferrin A, demonstrating that ornithine is an intermediate in staphyloferrin A biosynthesis.