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.