Diverse domain architectures of CheA histidine kinase, a central component of bacterial and archaeal chemosensory systems.

We found that in contrast to the best-studied model organisms, such as and , most bacterial and archaeal species have a CheA protein with a different domain composition. We report variations in CheA architecture, such as domain duplication and acquisition as well as class-specific domain composition. Our results will be of interest to those working on signal transduction in bacteria and archaea and lay the foundation for experimental studies.