4K0J: X-ray Crystal Structure Of A Heavy Metal Efflux Pump, Crystal Form I

Efflux pumps belonging to the ubiquitous resistance-nodulation-cell division (RND) superfamily transport substrates out of cells by coupling proton conduction across the membrane to a conformationally driven pumping cycle. The heavy metal-resistant bacteria Cupriavidus metallidurans CH34 relies notably on as many as 12 heavy metal efflux pumps of the RND superfamily. Here we show that C. metallidurans CH34 ZneA is a proton driven efflux pump specific for Zn(II), and that transport of substrates through the transmembrane domain may be electrogenic. We report two X-ray crystal structures of ZneA in intermediate transport conformations, at 3.0 and 3.7 A resolution. The trimeric ZneA structures capture protomer conformations that differ in the spatial arrangement and Zn(II) occupancies at a proximal and a distal substrate binding site. Structural comparison shows that transport of substrates through a tunnel that links the two binding sites, toward an exit portal, is mediated by the conformation of a short 14-aa loop. Taken together, the ZneA structures presented here provide mechanistic insights into the conformational changes required for substrate efflux by RND superfamily transporters.
PDB ID: 4K0JDownload
MMDB ID: 113908
PDB Deposition Date: 2013/4/4
Updated in MMDB: 2013/12
Experimental Method:
x-ray diffraction
Resolution: 3  Å
Source Organism:
Similar Structures:
Biological Unit for 4K0J: trimeric; determined by author and by software (PISA)
Molecular Components in 4K0J
Label Count Molecule
Proteins (3 molecules)
Heavy Metal Cation Tricomponent Efflux Pump Znea(czca- Like)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB