Cloning and characterization of a Campylobacter jejuni iron-uptake operon.
We report that C. jejuni modifies its outer membrane protein (OMP) repertoire when cultivated under iron-limiting conditions such as during incubation with epithelial cells. To identify genes encoding de novo expressed OMPs, a C. jejuni cosmid library was screened with antisera raised against proteins expressed in the presence of epithelial cells. A single clone was identified encoding an 80-kDa antigen. Sequence analysis of subclones identified an operon of three open reading frames (ORFs) encoding proteins that are homologous to the E. coli ferrichrome uptake system encoded by the fhu locus. Under low-iron conditions, C. jejuni expressed the 80-kDa OMP, indicating that its expression is regulated by the presence of iron. Southern blot analysis indicated that six of eleven isolates of C. jejuni harbor a fhuA homolog which, like all other DNA in this region sequenced thus far, is strikingly GC-rich (65%) compared with the C. jejuni genome (35% G+C).
Galindo
M A
MA
Department of Veterinary Science and Microbiology, The University of Arizona, Tucson, Arizona 85721, USA.
Day
W A
WA
Raphael
B H
BH
Joens
L A
LA
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001483:Base Sequence; D001692:Biological Transport; D016123:Campylobacter jejuni / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D029968:Escherichia coli Proteins / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D007501:Iron / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics*; D033902:Periplasmic Binding Proteins; D011991:Receptors, Virus / Q000235:genetics; D017422:Sequence Analysis, DNA
D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C050900:FhuA protein, E coli; D026901:Membrane Transport Proteins; D033902:Periplasmic Binding Proteins; D011991:Receptors, Virus; C069968:fhuB protein, E coli; C069969:fhuD protein, E coli; D007501:Iron