LRAT-specific domain facilitates vitamin A metabolism by domain swapping in HRASLS3
- Case Western Reserve Univ., Cleveland, OH (United States). School of Medicine. Cleveland Center for Membrane and Structural Biology. Dept. of Pharmacology
Cellular uptake of vitamin A, production of visual chromophore and triglyceride homeostasis in adipocytes depend on two representatives of the vertebrate N1pC/P60 protein family, lecithin:retinol acyltransferase (LRAT) and HRAS-like tumor suppressor 3 (HRASLS3). Both proteins function as lipid-metabolizing enzymes but differ in their substrate preferences and dominant catalytic activity. The mechanism of this catalytic diversity is not understood. In this paper, by using a gain-of-function approach, we identified a specific sequence responsible for the substrate specificity of N1pC/P60 proteins. A 2.2-Å crystal structure of the HRASLS3-LRAT chimeric enzyme in a thioester catalytic intermediate state revealed a major structural rearrangement accompanied by three-dimensional domain swapping dimerization not observed in native HRASLS proteins. Structural changes affecting the active site environment contributed to slower hydrolysis of the catalytic intermediate, supporting efficient acyl transfer. Finally, these findings reveal structural adaptation that facilitates selective catalysis and mechanism responsible for diverse substrate specificity within the LRAT-like enzyme family.
- Research Organization:
- Case Western Reserve Univ., Cleveland, OH (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER); USDOE Office of Science (SC), Basic Energy Sciences (BES); National Inst. of Health (NIH) (United States)
- Grant/Contract Number:
- AC02-06CH11357; EY023948; EY009339; T32 GM007250; P41RR012408; P41GM103473
- OSTI ID:
- 1168504
- Journal Information:
- Nature Chemical Biology, Vol. 11, Issue 1; ISSN 1552-4450
- Publisher:
- Nature Publishing GroupCopyright Statement
- Country of Publication:
- United States
- Language:
- ENGLISH
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