Cloning, expression and sequence analysis of the Bartonella henselae gene encoding the HtrA stress-response protein.

A cloned fragment of Bartonella (Rochalimaea) henselae (Bh) DNA was found to direct synthesis of an immunoreactive protein in Escherichia coli (Ec). Sequence analysis revealed an open reading frame of 1509 nucleotides encoding a protein of 503 amino acids that exhibited extensive identity (over the entire protein) with the HtrA stress-response proteins of Brucella abortus (59%), Ec (37%) and Salmonella typhimurium (36%). When the putative htrA gene was amplified by polymerase chain reaction and used as template for in vitro transcription and translation, a protein with an apparent molecular mass of 62 kDa was synthesized from the plasmid template. These results suggest that the immunoreactive Bh protein is homologous to the HtrA class of stress-response proteins.