Abiko Layara Akemi, Dias Teixeira Raphael, Engilberge Sylvain, Grahl Anne, Mühlethaler Tobias, Sharpe Timothy, Grzesiek Stephan
Biozentrum, University of Basel, Basel, Switzerland.
Paul Scherrer Institut, Villigen, Switzerland.
Nat Chem. 2022 Oct;14(10):1133-1141. doi: 10.1038/s41557-022-01009-9. Epub 2022 Aug 11.
Recent high-pressure NMR results indicate that the preactive conformation of the β-adrenergic receptor (βAR) harbours completely empty cavities of ~100 Å volume, which disappear in the active conformation of the receptor. Here we have localized these cavities using X-ray crystallography of xenon-derivatized βAR crystals. One of the cavities is in direct contact with the cholesterol-binding pocket. Solution NMR shows that addition of the cholesterol analogue cholesteryl hemisuccinate impedes the formation of the active conformation of detergent-solubilized βAR by blocking conserved G protein-coupled receptor microswitches, concomitant with an affinity reduction of both isoprenaline and G protein-mimicking nanobody Nb80 for βAR detected by isothermal titration calorimetry. This wedge-like action explains the function of cholesterol as a negative allosteric modulator of βAR. A detailed understanding of G protein-coupled receptor regulation by cholesterol by filling of a dry void and the easy scouting for such voids by xenon may provide new routes for the development of allosteric drugs.
最近的高压核磁共振结果表明，β-肾上腺素能受体（βAR）的预激活构象具有约100 Å体积的完全空的腔，这些腔在受体的激活构象中消失。在这里，我们利用氙衍生化βAR晶体的X射线晶体学对这些腔进行了定位。其中一个腔与胆固醇结合口袋直接接触。溶液核磁共振显示，添加胆固醇类似物胆固醇半琥珀酸酯会通过阻断保守的G蛋白偶联受体微开关来阻碍去污剂溶解的βAR活性构象的形成，同时等温滴定量热法检测到异丙肾上腺素和模拟G蛋白的纳米抗体Nb80对βAR的亲和力降低。这种楔形作用解释了胆固醇作为βAR负变构调节剂的功能。通过填充一个干燥的空隙来详细了解胆固醇对G蛋白偶联受体的调节作用，以及利用氙轻松探测此类空隙，可能为变构药物的开发提供新途径。
