5EPV: Histidine kinase domain from the LOV-HK blue-light receptor from Brucella abortus

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.
PDB ID: 5EPVDownload
MMDB ID: 136759
PDB Deposition Date: 2015/11/12
Updated in MMDB: 2017/12
Experimental Method:
x-ray diffraction
Resolution: 2.51  Å
Source Organism:
Similar Structures:
Biological Unit for 5EPV: monomeric; determined by author
Molecular Components in 5EPV
Label Count Molecule
Protein (1 molecule)
Blue-light-activated Histidine Kinase(Gene symbol: BME_RS13525)
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

Citing MMDB