1py6 | pdb_00001py6
Bacteriorhodopsin crystallized from bicells
|
Overview
The molecular forces that stabilize membrane protein structure are poorly understood. To investigate these forces we introduced alanine substitutions at 24 positions in the B helix of bacteriorhodopsin and examined their effects on structure and stability. Although most of the results can be rationalized in terms of the folded structure, there are a number of surprises. (1) We find a remarkably high frequency of stabilizing mutations (17%), indicating that membrane proteins are not highly optimized for stability. (2) Helix B is kinked, with the kink centered around Pro50. The P50A mutation has no effect on stability, however, and a crystal structure reveals that the helix remains bent, indicating that tertiary contacts dominate in the distortion of this helix. (3) We find that the protein is stabilized by about 1kcal/mol for every 38A(2) of surface area buried, which is quite similar to soluble proteins in spite of their dramatically different environments. (4) We find little energetic difference, on average, in the burial of apolar surface or polar surface area, implying that van der Waals packing is the dominant force that drives membrane protein folding.
About this Structure
1PY6 is a Single protein structure of sequence from Halobacterium salinarum with RET as ligand. Full crystallographic information is available from OCA.
Reference
Side-chain contributions to membrane protein structure and stability., Faham S, Yang D, Bare E, Yohannan S, Whitelegge JP, Bowie JU, J Mol Biol. 2004 Jan 2;335(1):297-305. PMID:14659758
Page seeded by OCA on Thu Feb 21 14:33:52 2008
