Journal
BIOCHEMICAL JOURNAL
Volume 436, Issue -, Pages 591-597Publisher
PORTLAND PRESS LTD
DOI: 10.1042/BJ20110091
Keywords
isomerohydrolase; liposome; membrane-associated protein; retinyl ester (RE); RPE65
Categories
Funding
- National Institutes of Health [EY018659, EY012231, EY019309, P20RR024215]
- American Diabetes Association
Ask authors/readers for more resources
The visual cycle is a multi-step pathway to recycle 11-cis retinal, the chromophore for both rod and cone visual pigments. The isomerohydrolase RPE65, a membrane-associated enzyme, converts atRE (all-trans-retinyl ester) to 11-cis-retinol, a key step in the visual cycle. Previously, it has been shown that membrane association of RPE65 is essential for its catalytic activity. Using purified recombinant chicken RPE65 and an in vitro liposome-based floatation assay, we present evidence that the RPE65 membrane-binding affinity was significantly facilitated by incorporation of atRE, the substrate of RPE65, into liposomal membrane. Using tryptophan emission fluorescence quenching and CD spectroscopy, we showed that, upon membrane binding, RPE65 undergoes conformational changes at both the tertiary and secondary structural levels. Specifically, tryptophan fluorescence quenching showed that the tertiary RPE65 structure became more open towards the hydrophilic environment upon its association with the membrane. Simultaneously, a decrease in the a-helix content of RPE65 was revealed upon binding with the lipid membrane containing atRE. These results demonstrated that RPE65's functional activity depends on its conformational changes caused by its association with the membrane.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available