Nucleotide sequences of the sfuA, sfuB, and sfuC genes of Serratia marcescens suggest a periplasmic-binding-protein-dependent iron transport mechanism.
The cloned sfu region of the Serratia marcescens chromosome confers the ability to grow on iron-limited media to an Escherichia coli K-12 strain that is unable to synthesize a siderophore. This DNA fragment was sequenced and found to contain three genes termed sfuA, sfuB, and sfuC, arranged and transcribed in that order. The sfuA gene encoded a periplasmic polypeptide with calculated molecular weights of 36,154 for the precursor and 33,490 for the mature protein. The sfuB gene product was a very hydrophobic protein with a molecular weight of 56,589. The sfuC gene was found to encode a rather polar but membrane-bound protein with a molecular weight of 36,671 which exhibited strong homology to consensus sequences of nucleotide-binding proteins. The number, structural characteristics, and locations of the SfuABC proteins were typical of a periplasmic-binding-protein-dependent transport mechanism. How Fe3+ is solubilized and taken up across the outer membrane remains an enigma.
Mikrobiologie II, Universität Tübingen, Federal Republic of Germany.
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Angerer
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Gaisser
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Braun
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics*; D003062:Codon / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D007501:Iron / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D033902:Periplasmic Binding Proteins; D010957:Plasmids; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D012706:Serratia marcescens / Q000235:genetics* / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; D003062:Codon; D004269:DNA, Bacterial; D008565:Membrane Proteins; D015345:Oligonucleotide Probes; D033902:Periplasmic Binding Proteins; C062885:sfu proteins, Serratia marcescens; D007501:Iron