3LI8: Crystal Structure of the extracellular domain of the putative histidine kinase mmHK1S-Z2

Histidine kinase (HK) receptors are used ubiquitously by bacteria to monitor environmental changes, and they are also prevalent in plants, fungi, and other protists. Typical HK receptors have an extracellular sensor portion that detects a signal, usually a chemical ligand, and an intracellular transmitter portion that includes both the kinase domain itself and the site for histidine phosphorylation. While kinase domains are highly conserved, sensor domains are diverse. HK receptors function as dimers, but the molecular mechanism for signal transduction across cell membranes remains obscure. In this study, eight crystal structures were determined from five sensor domains representative of the most populated family, family HK1, found in a bioinformatic analysis of predicted sensor domains from transmembrane HKs. Each structure contains an inserted repeat of PhoQ/DcuS/CitA (PDC) domains, and similarity between sequence and structure is correlated across these and other double-PDC sensor proteins. Three of the five sensors crystallize as dimers that appear to be physiologically relevant, and comparisons between ligated structures and apo-state structures provide insights into signal transmission. Some HK1 family proteins prove to be sensors for chemotaxis proteins or diguanylate cyclase receptors, implying a combinatorial molecular evolution.
PDB ID: 3LI8Download
MMDB ID: 81868
PDB Deposition Date: 2010/1/24
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 1.75  Å
Source Organism:
Similar Structures:
Biological Unit for 3LI8: monomeric; determined by author
Molecular Components in 3LI8
Label Count Molecule
Protein (1 molecule)
Hypothetical Sensory Transduction Histidine Kinase
Molecule annotation
Chemicals (6 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB