Centre for Discovery Brain Sciences, Deanery of Biomedical Sciences, University of Edinburgh, Edinburgh, UK.
Centre for Discovery Brain Sciences, Deanery of Biomedical Sciences, University of Edinburgh, Edinburgh, UK
Life Sci Alliance. 2023 Jan 19;6(4). doi: 10.26508/lsa.202201791. Print 2023 Apr.
Human transmembrane adenylyl cyclase 9 (AC9) is not regulated by heterotrimeric G proteins. Key to the resistance to stimulation by Gs-coupled receptors (GsRs) is auto-inhibition by the COOH-terminal domain (C2b). The present study investigated the role of the C2b domain in the regulation of cyclic AMP production by AC9 in HEK293FT cells expressing the GloSensor22F cyclic AMP-reporter protein. Surprisingly, we found C2b to be essential for sustaining the basal output of cyclic AMP by AC9. A human mutation (E326D) in the parallel coiled-coil formed by the signalling helices of AC9 dramatically increased basal activity, which was also dependent on the C2b domain. Intriguingly, the same mutation enabled stimulation of AC9 by GsRs. In summary, auto-regulation by the C2b domain of AC9 sustains its basal activity and quenches activation by GsR. Thus, AC9 appears to be tailored to support constitutive activation of cyclic AMP effector systems. A switch from this paradigm to stimulation by GsRs may be occasioned by conformational changes at the coiled-coil or removal of the C2b domain.
人类跨膜腺苷酸环化酶 9（AC9）不受异三聚体 G 蛋白的调节。对 Gs 偶联受体（GsR）刺激的抗性的关键是由羧基末端结构域（C2b）的自动抑制。本研究探讨了 C2b 结构域在调节表达 GloSensor22F cAMP 报告蛋白的 HEK293FT 细胞中 AC9 的 cAMP 产生中的作用。令人惊讶的是，我们发现 C2b 对于维持 AC9 的基础 cAMP 输出是必不可少的。AC9 信号螺旋形成的平行卷曲螺旋中的人类突变（E326D）极大地增加了基础活性，这也依赖于 C2b 结构域。有趣的是，相同的突变使 AC9 能够被 GsR 刺激。总之，AC9 的 C2b 结构域的自动调节维持其基础活性并抑制 GsR 的激活。因此，AC9 似乎旨在支持 cAMP 效应系统的组成性激活。这种从这种模式到 GsR 刺激的转变可能是卷曲螺旋的构象变化或 C2b 结构域的去除引起的。
