5epv
From Proteopedia
Histidine kinase domain from the LOV-HK blue-light receptor from Brucella abortus
Structural highlights
Function[LOVHK_BRUA2] Photosensitive kinase that is involved in increased bacterial virulence upon exposure to light. Once ejected from an infected animal host, sunlight acts as an environmental signal that increases the virulence of the bacterium, preparing it for infection of the next host (By similarity). This photoreceptor protein is directly related to the bacterium's survival and replication within host macrophages, as it is required for optimal replication of bacteria inside macrophages.[1] Publication Abstract from PubMedIn 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. Structural Insights into the HWE Histidine Kinase Family: The Brucella Blue Light-Activated Histidine Kinase Domain.,Rinaldi J, Arrar M, Sycz G, Cerutti ML, Berguer PM, Paris G, Estrin DA, Marti MA, Klinke S, Goldbaum FA J Mol Biol. 2016 Feb 2. pii: S0022-2836(16)00081-4. doi:, 10.1016/j.jmb.2016.01.026. PMID:26851072[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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