These proteins share a highly-conserved sequence at their N-terminus. They include several proteins from Rhodopirellula baltica and also several from proteobacteria. The proteins are produced by the Batl operon which appears to be important in pathogenicity and aerotolerance. This family is the conserved N-terminus, but the full length proteins carry multiple membrane-spanning domains. BatA ensures bacterial survival in the early stages of the infection process, when the infected sites are aerobic, and is produced under conditions of oxidative stress.