Identification of a partition region carried by the plasmid QpH1 of Coxiella burnetii.
Coxiella burnetii is an intracellular bacterial pathogen which causes Q fever in humans and other animals. Most of the isolates found carry plasmids which share considerable homology. Unfortunately all of these plasmids remain cryptic. Initial attempts to look for secreted or membrane proteins encoded by these plasmids using TnphoA mutagenesis revealed an open reading frame on the EcoRI-fragment C of the plasmid QpH1. Upstream DNA sequencing of the TnphoA insertions revealed a deduced peptide sequence with homology to the SopA protein which is encoded by the F plasmid in Escherichia coli. Maxicell analysis showed that fragment C encoded two proteins: one was 43.5 kDa in size and designated QsopA, and a second was 38 kDa in size. These proteins are similar in molecular weight to the SopA and SopB proteins, which are essential components of the partition mechanism of the F plasmid. The region appears to be conserved in plasmids QpRS, QpDV, and QpDG, but is absent in a plasmidless isolate in which plasmid sequences have integrated into the chromosomal DNA. Complementation studies demonstrated that fragment C has a plasmid partitioning function and can restore maintenance stability of the partition-defective mini-F plasmid. These data suggest that fragment C carries the plasmid partition region of the plasmid QpH1.
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Department of Microbiology, Washington State University, Pullman 99164-4233.
Mallavia
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LP
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D002455:Cell Division; D016997:Coxiella burnetii / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D016366:Open Reading Frames; D010957:Plasmids / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; C060971:SopA protein, Bacteria