Iron-hydroxamate uptake systems in Bacillus subtilis: identification of a lipoprotein as part of a binding protein-dependent transport system.
Bacillus subtilis was shown to utilize three types of hydroxamate siderophores, ferrichromes, ferrioxamines and shizokinen, each of which is taken up by different transport systems. Mutants deficient in the uptake of ferrichrome and/or ferrioxamine B were isolated. The gene fhuD, which was able to complement a mutant defective in ferrichrome uptake, was cloned. The deduced sequence of FhuD showed low but significant homology to the binding proteins FepB, FecB and FhuD of Escherichia coli, which are all components of binding protein-dependent, ferric siderophore transport systems. The first 23 amino acids of FhuD of B. subtilis possessed all characteristics of a lipoprotein signal sequence. The processing of FhuD in E. coli was inhibited by globomycin. Inhibition by globomycin indicated a lipid modification at the N-terminal cysteine in E. coli. It is highly likely that this step may also take place in B. subtilis. As in other binding protein-dependent transport systems of Gram-positive organisms it is proposed that the lack of a periplasm is compensated for by the lipid through which the binding protein is anchored to the cytoplasmic membrane.
Lehrstuhl für Mikrobiologie II, Universität Tübingen, Germany.
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R
Schneider
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K
Hantke
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents; D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001692:Biological Transport / Q000187:drug effects; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism; D029968:Escherichia coli Proteins; D005290:Ferric Compounds / Q000378:metabolism* / Q000494:pharmacology; D005291:Ferrichrome / Q000031:analogs & derivatives / Q000494:pharmacology; D005798:Genes, Bacterial; D006877:Hydroxamic Acids / Q000378:metabolism*; D016623:Ion Pumps; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D010455:Peptides / Q000494:pharmacology; D033902:Periplasmic Binding Proteins; D033903:Periplasmic Proteins; D011956:Receptors, Cell Surface / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D017262:Siderophores / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D005290:Ferric Compounds; D006877:Hydroxamic Acids; D016623:Ion Pumps; D008074:Lipoproteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D010455:Peptides; D033902:Periplasmic Binding Proteins; D033903:Periplasmic Proteins; D011956:Receptors, Cell Surface; D017262:Siderophores; C061266:fepB protein, E coli; C074579:iron (III) hydroxamate; C035902:siderophore receptors; C069969:fhuD protein, E coli; C069970:FecB protein, E coli; D005291:Ferrichrome; C015657:albomycin; C072459:ferrimycin; C017339:globomycin