1umx

From Proteopedia

Revision as of 15:53, 18 December 2007

PHOTOSYNTHETIC REACTION CENTER MUTANT WITH ARG M267 REPLACED WITH LEU (CHAIN M, R267L)

Overview

Relatively little is known about the functions of specific molecular, interactions between membrane proteins and membrane lipids. The structural, and functional consequences of disrupting a previously identified, interaction between a molecule of the diacidic lipid cardiolipin and the, purple bacterial reaction centre were examined. Mutagenesis of a highly, conserved arginine (M267) that is responsible for binding the head-group, of the cardiolipin (to leucine) did not affect the rate of photosynthetic, growth, the functional properties of the reaction centre, or the X-ray, crystal structure of the complex (determined to a resolution of 2.8 A)., However, the thermal stability of the protein was compromised by this, mutation, part of the reaction centre population showing an approximately, 5 degrees C decrease in melting temperature in response to the arginine to, leucine mutation. The crystallised mutant reaction centre also no longer, bound detectable amounts of cardiolipin at this site. Taken together, these observations suggest that this particular protein-lipid interaction, contributes to the thermal stability of the complex, at least when in, detergent micelles. These findings are discussed in the light of proposals, concerning the unfolding processes that occur when membrane proteins are, heated, and we propose that one function of the cardiolipin is to, stabilise the interaction between adjacent membrane-spanning alpha-helices, in a region where there are no direct protein-protein interactions.

About this Structure

1UMX is a Protein complex structure of sequences from Rhodobacter sphaeroides with FE, PO4, LDA, BCL, BPB, SPN and U10 as ligands. Known structural/functional Site: . Full crystallographic information is available from OCA.

Reference

Disruption of a specific molecular interaction with a bound lipid affects the thermal stability of the purple bacterial reaction centre., Fyfe PK, Isaacs NW, Cogdell RJ, Jones MR, Biochim Biophys Acta. 2004 Jan 30;1608(1):11-22. PMID:14741581

Page seeded by OCA on Tue Dec 18 18:03:39 2007