Research Article

Structural Changes in Bacteriorhodopsin During Ion Transport at 2 Angstrom Resolution

Science  08 Oct 1999:
Vol. 286, Issue 5438, pp. 255-260
DOI: 10.1126/science.286.5438.255

You are currently viewing the abstract.

View Full Text

Via your Institution

Log in through your institution

Log in through your institution


Abstract

Crystal structures of the Asp96 to Asn mutant of the light-driven proton pump bacteriorhodopsin and its M photointermediate produced by illumination at ambient temperature have been determined to 1.8 and 2.0 angstroms resolution, respectively. The trapped photoproduct corresponds to the late M state in the transport cycle—that is, after proton transfer to Asp85 and release of a proton to the extracellular membrane surface, but before reprotonation of the deprotonated retinal Schiff base. Its density map describes displacements of side chains near the retinal induced by its photoisomerization to 13-cis,15-anti and an extensive rearrangement of the three-dimensional network of hydrogen-bonded residues and bound water that accounts for the changed pK a values (where K a is the acid constant) of the Schiff base and Asp85. The structural changes detected suggest the means for conserving energy at the active site and for ensuring the directionality of proton translocation.

  • * To whom correspondence should be addressed. E-mail: hudel{at}uci.edu or jlanyi{at}orion.oac.uci.edu

View Full Text

Related Content