期刊
JOURNAL OF MOLECULAR RECOGNITION
卷 22, 期 4, 页码 307-318出版社
WILEY
DOI: 10.1002/jmr.949
关键词
adrenergic; GPCR; G-protein; agonist; antagonist; activation; flexible docking; binding energy
资金
- NIH [5-R01-GM071872, 1-R01-GM074832]
- Roadmap Initiative grant [P50 GM07319]
The 2.4 angstrom crystal structure of the beta(2)-adrenergic receptor (beta(2)AR) in complex with the high-affinity inverse agonist (-)-carazolol provides a detailed structural framework for the analysis of ligand recognition by adrenergic receptors. Insights into agonist binding and the corresponding conformational changes triggering G-protein coupled receptor (GPCR) activation mechanism are of special interest. Here we show that while the carazolol pocket captured in the beta(2)AR crystal structure accommodates (-)-isoproterenol and other agonists without steric clashes, a finite movement of the flexible extracellular part of TM-V helix (TM-Ve) obtained by receptor optimization in the presence of docked ligand can further improve the calculated binding affinities for agonist compounds. Tilting of TM-Ve towards the receptor axis provides a more complete description of polar receptor-ligand interactions for full and partial agonists, by enabling optimal engagement of agonists with two experimentally identified anchor sites, formed by Asp113/Asn312 and Ser203/Ser204/Ser207 side chains. Further, receptor models incorporating a flexible TM-V backbone allow reliable prediction of binding affinities for a set of diverse ligands, suggesting potential utility of this approach to design of effective and subtype-specific agonists for adrenergic receptors. Systematic differences in capacity of partial, full and inverse agonists to induce TM-V helix tilt in the beta(2)AR model suggest potential role of TM-V as a conformational rheostat involved in the whole spectrum of beta(2)AR responses to small molecule signals. Copyright (C) 2009 John Wiley & Sons, Ltd.
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