2O9D

Crystal Structure of AqpZ mutant T183C.

Summary for 2O9D

• Entry DOI: 10.2210/pdb2o9d/pdb
• Related: 2O9E 2O9F 2O9G
• Descriptor: Aquaporin Z, octyl alpha-L-altropyranoside, octyl beta-D-galactopyranoside, ... (4 entities in total)
• Functional Keywords: aquaporin, integral membrane protein, structural genomics, psi-2, protein structure initiative, center for structures of membrane proteins, csmp, membrane protein
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 48844.86

Authors

Savage, D.F.,Stroud, R.M.,Center for Structures of Membrane Proteins (CSMP) (deposition date: 2006-12-13, release date: 2007-02-13, Last modification date: 2023-12-27)

Primary citation

Savage, D.F.,Stroud, R.M.
Structural basis of aquaporin inhibition by mercury.
J.Mol.Biol., 368:607-617, 2007

PubMed Abstract: The aquaporin family of channels was defined based on the inhibition of water transport by mercurial compounds. Despite the important role of mercurials, little is known about the structural changes involved upon mercury binding leading to channel inhibition. To elucidate the mechanism we designed a mutant, T183C, of aquaporin Z (AqpZ) patterned after the known mercury-sensitive site of aquaporin 1 (AQP1) and determined the X-ray crystal structures of the unbound and mercury blocked states. Superposition of the two structures shows no conformational rearrangement upon mercury binding. In the blocked structure, there are two mercury sites, one bound to Cys183 and occluding the pore, and a second, also bound to the same cysteine but found buried in an interstitial cavity. To test the mechanism of blockade we designed a different mutant, L170C, to produce a more effective mercury block at the pore site. In a dose-response inhibition study, this mutant was 20 times more sensitive to mercury than wild-type AqpZ and four times more sensitive than T183C. The X-ray structure of L170C shows four mercury atoms at, or near, the pore site defined in the T183C structure and no structural change upon mercury binding. Thus, we elucidate a steric inhibition mechanism for this important class of channels by mercury.

PubMed: 17376483
DOI: 10.1016/j.jmb.2007.02.070

Experimental method

X-RAY DIFFRACTION (2.3 Å)