Characterization of a Rickettsia rickettsii DNA fragment analogous to the fir A-ORF17-lpxA region of Escherichia coli.
The firA and lpxA genes, as well as an ORF coding for a putative 16-kDa protein of unknown function, have been identified and characterized in the obligate intracellular bacterium. Rickettsia rickettsii. This is the first description of these genes, which code for enzymes involved in the biosynthesis of lipid A, in a species outside of the Enterobacteriaceae. The deduced amino acid (aa) sequences of FirA, ORF16 and LpxA of R. rickettsii, when compared to their Escherichia coli analogs, exhibited 35, 44 and 41% aa identity, respectively. In addition, the order of genes in R. rickettsii, firA-ORF16-lpxA, was identical to that found in E. coli; however, the spacing between the rickettsial genes was greater. Interestingly, the R. rickettsii FirA and LpxA deduced proteins retain an unusual hexapeptide repeat pattern found in E. coli and Salmonella typhimurium FirA/Ssc and E. coli LpxA, as well as other acyltransferases, providing additional support for the importance of this structure.
Shaw
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Department of Microbiology and Immunology, University of South Alabama College of Medicine, Mobile 36688.
Wood
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D000217:Acyltransferases / Q000235:genetics; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D017124:Conserved Sequence; D004269:DNA, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000235:genetics; D016366:Open Reading Frames; D012091:Repetitive Sequences, Nucleic Acid; D012284:Rickettsia rickettsii / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D009842:Oligopeptides; D000217:Acyltransferases; C050304:acyl-(acyl-carrier-protein)-UDP-N-acetylglucosamine acyltransferase