How Do Short Chain Nonionic Detergents Destabilize G-Protein-Coupled Receptors?

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• 作者：Sangbae Lee ; Allen Mao ; Supriyo Bhattacharya ; Nathan Robertson ; Reinhard Grisshammer ; Christopher G. Tate ; Nagarajan Vaidehi
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：November 30, 2016
• 年：2016
• 卷：138
• 期：47
• 页码：15425-15433
• 全文大小：606K
• ISSN：1520-5126

文摘

Stability of detergent-solubilized G-protein-coupled receptors (GPCRs) is crucial for their purification in a biologically relevant state, and it is well-known that short chain detergents such as octylglucoside are more denaturing than long chain detergents such as dodecylmaltoside. However, the molecular basis for this phenomenon is poorly understood. To gain insights into the mechanism of detergent destabilization of GPCRs, we used atomistic molecular dynamics simulations of thermostabilized adenosine receptor (A_2AR) mutants embedded in either a lipid bilayer or detergent micelles of alkylmaltosides and alkylglucosides. A_2AR mutants in dodecylmaltoside or phospholipid showed low flexibility and good interhelical packing. In contrast, A_2AR mutants in either octylglucoside or nonylglucoside showed decreased α-helicity in transmembrane regions, decreased α-helical packing, and the interpenetration of detergent molecules between transmembrane α-helices. This was not observed in octylglucoside containing phospholipid. Cholesteryl hemisuccinate in dodecylmaltoside increased the energetic stability of the receptor by wedging into crevices on the hydrophobic surface of A_2AR, increasing packing interactions within the receptor and stiffening the detergent micelle. The data suggest a three-stage process for the initial events in the destabilization of GPCRs by octylglucoside: (i) highly mobile detergent molecules form small micelles around the receptor; (ii) loss of α-helicity and decreased interhelical packing interactions in transmembrane regions are promoted by increased receptor thermal motion; (iii) transient separation of transmembrane helices allowed penetration of detergent molecules into the core of the receptor. The relative hydration of the headgroup and alkyl chain correlates with detergent harshness and suggests new avenues to develop milder versions of octylglucoside for receptor crystallization.