4HYJ: Crystal Structure Of Exiguobacterium Sibiricum Rhodopsin

Light-driven proton pumps are present in many organisms. Here, we present a high-resolution structure of a proteorhodopsin from a permafrost bacterium, Exiguobacterium sibiricum rhodopsin (ESR). Contrary to the proton pumps of known structure, ESR possesses three unique features. First, ESR's proton donor is a lysine side chain that is situated very close to the bulk solvent. Second, the alpha-helical structure in the middle of the helix F is replaced by 310- and pi-helix-like elements that are stabilized by the Trp-154 and Asn-224 side chains. This feature is characteristic for the proteorhodopsin family of proteins. Third, the proton release region is connected to the bulk solvent by a chain of water molecules already in the ground state. Despite these peculiarities, the positions of water molecule and amino acid side chains in the immediate Schiff base vicinity are very well conserved. These features make ESR a very unusual proton pump. The presented structure sheds light on the large family of proteorhodopsins, for which structural information was not available previously.
PDB ID: 4HYJDownload
MMDB ID: 111831
PDB Deposition Date: 2012/11/13
Updated in MMDB: 2013/09
Experimental Method:
x-ray diffraction
Resolution: 2.3  Å
Source Organism:
Similar Structures:
Biological Unit for 4HYJ: monomeric; determined by author and by software (PISA)
Molecular Components in 4HYJ
Label Count Molecule
Protein (1 molecule)
Molecule annotation
Chemicals (14 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB