A heat shock operon in Coxiella burnetii produces a major antigen homologous to a protein in both mycobacteria and Escherichia coli

A gene library from the DNA of Coxiella burnetii has been constructed in the cosmid vector pHC79. A particular clone, pJB196, reacted strongly with Coxiella -specific antibodies elicited in a number of different species of animals. This clone produced two abundant C. burnetii -specific polypeptides, a 14-kilodalton nonimmunoreactive protein and a 62-kilodalton immunoreactive protein. Sequencing identified two open reading frames, encoding polypeptides of 10.5 and 58.3 kilodaltons. The only transcriptional control element observed on the 5' side of the initiation codon resembled a heat shock promoter. This heat shock promoter was functionally regulated in Escherichia coli , since both proteins were produced by growth conditions at 37 degree C and neither protein was detected at 23 degree C. There were four sequences from the literature that were highly homologous (> 50%) to the 62-kilodalton protein from C. burnetii .