期刊
JOURNAL OF MOLECULAR BIOLOGY
卷 428, 期 6, 页码 1165-1179出版社
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmb.2016.01.026
关键词
signal transduction; two-component system; X-ray crystallography; molecular dynamics simulations; autophosphorylation mechanism
资金
- Argentinian Ministry of Science
- Argentinian Research Council
- National Science Foundation Postdoctoral Research Fellowship in Biology [DBI-1401889]
- Direct For Biological Sciences
- Div Of Biological Infrastructure [1401889] Funding Source: National Science Foundation
In response to light, as part of a two-component system, the Brucella blue light-activated histidine kinase (LOV-HK) increases its autophosphorylation, modulating the virulence of this microorganism. The Brucella histidine kinase (HK) domain belongs to the HWE family, for which there is no structural information. The HWE family is exclusively present in proteobacteria and usually coupled to a wide diversity of light sensor domains. This work reports the crystal structure of the Brucella HK domain, which presents two different dimeric assemblies in the asymmetric unit: one similar to the already described canonical parallel homodimers (C) and the other, an antiparallel non-canonical (NC) dimer, each with distinct relative subdomain orientations and dimerization interfaces. Contrary to these crystallographic structures and unlike other HKs, in solution, the Brucella HK domain is monomeric and still active, showing an astonishing instability of the dimeric interface. Despite this instability, using cross-linking experiments, we show that the C dimer is the functionally relevant species. Mutational analysis demonstrates that the autophosphorylation activity occurs in cis. The different relative subdomain orientations observed for the NC and C states highlight the large conformational flexibility of the HK domain. Through the analysis of these alternative conformations by means of molecular dynamics simulations, we also propose a catalytic mechanism for Brucella LOV-HK. (C) 2016 Elsevier Ltd. All rights reserved.
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