The structure of a natural competency protein from the thermophilic bacterium Thermus thermophilus

Abstract

Natural transformation is an important mode of horizontal gene transmission in bacteria, a process that underlies the ability of these organisms to evolve rapidly and diverge into the vast multitude of forms that are observed in nature. The sharing of bacterial genes has become of increasing significance when studying the causes of bacterial drug resistance. Despite its importance, the state of competency that allows the uptake of DNA from the environment remains poorly understood in gram-negative bacteria. The highly thermophilic eubacterium Thermus thermophilus has become a focus of work seeking to elucidate the steps involved in natural transformation, the underlying developmental state of competency, and its link to type IV pilus formation. The protein ComZ has been shown to be required for competency in T. thermophilus but contains no detectable homology to other protein components of the apparatus or indeed any known proteins, with the exception of ComZ from very closely related species. During this project, ComZ was expressed, purified to homogeneity and studied via X-ray crystallography and yielded experimental phase data that allowed computation of an electron density map at 3.5 A resolution. In addition, the thermostability and domain architecture of ComZ was also studied by other methods. An initial model of ComZ is presented here, which shows a two domain structure comprising an alpha/beta domain and a 3 stranded parallel beta helix. This structure suggests that ComZ might have an enzymatic or binding role in natural competence.

Date of Award	1 Aug 2016
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Jeremy Derrick (Supervisor) & Stephen Prince (Supervisor)