ISOLATION AND CHARACTERIZATION OF THE DNAA GENE OF RICKETTSIA-PROWAZEKII

The dnaA gene encoding the initiator protein of DNA replication was is olated from the obligate intracellular bacterium, Rickettsia prowazeki i. Comparison of the deduced amino acid sequence of R. prowazekii DnaA with other bacterial DnaA proteins revealed extensive similarity. How ever, the rickettsial sequence is unique in the number of basic lysine residues found within a highly conserved portion of the putative DNA binding region, suggesting that the rickettsial protein may recognize a DNA sequence that differs from the consensus DnaA box sequence ident ified in other bacteria. Consensus DnaA box sequences, found upstream of many bacterial dnaA genes, were not identified upstream of ricketts ial dnaA gene. In addition, gene organization within this region diffe red from that of other bacteria. The putative start of transcription o f the rickettsial dnaA gene was localized to a site 522 nucleotides (n t) upstream of the DnaA start codon.