Adenylyl Cyclase 5 Regulation by Gβγ Involves Isoform-Specific Use of Multiple Interaction Sites
Adenylyl Cyclase 5 Regulation by Gβγ Involves Isoform-Specific Use of Multiple Interaction Sites
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DOI：
10.1124/mol.115.099556
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发表时间：
2015-10-01
影响因子：
3.6
通讯作者：
Dessauer, Carmen W.
中科院分区：
文献类型：
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作者：
Brand, Cameron S.;Sadana, Rachna;Dessauer, Carmen W.
腺苷酸环化酶 (AC) 将 ATP 转化为环 AMP (cAMP)，后者是细胞信号传导中重要的第二信使。异三聚体 G 蛋白和其他调节因子对于控制 AC 活性非常重要。根据 AC 同工型，G beta gamma 亚基可以有条件地刺激或抑制 cAMP 合成。我们之前表明 G α(s)-β γ 异三聚体与 5 型 AC (AC5) 的 N 末端 (NT) 结合。我们现在证明 G beta gamma 与多种 AC 亚型的 NT 结合。我们假设涉及非活性异三聚体的 G beta gamma/AC5 相互作用和 AC5 的 G beta gamma 刺激是可分离的事件。 G beta gamma“热点”的突变表明该位点对于 AC5 刺激是必需的，但对于与 AC5NT 的前 198 个氨基酸（G 蛋白支架位点）相互作用则不是必需的。这与 AC6 形成对比，其中 G beta gamma 热点是与 AC6NT 相互作用和刺激 AC6 所必需的。此外，SIGK 热点肽会破坏 AC 异构体 1、2 和 6 的 G beta gamma 调节，但不会破坏 AC5。 G beta gamma 还结合 AC5 和 AC6 的 C1/C2 催化结构域。最后，细胞与全长 AC5 的相互作用取决于 G beta gamma 上的多个位点。这表明了一种异构体特异性机制，其中 AC5NT 上结合的 Gbg 非常适合 AC5 的时空控制。我们认为 AC 的 G beta gamma 调节涉及多个结合事件，并且 AC NT 在异三聚体 G 蛋白亚基调节机制中的作用是同种型特异性的。
Adenylyl cyclase (AC) converts ATP into cyclic AMP (cAMP), an important second messenger in cell signaling. Heterotrimeric G proteins and other regulators are important for control of AC activity. Depending on the AC isoform, G beta gamma subunits can either conditionally stimulate or inhibit cAMP synthesis. We previously showed that the G alpha(s)-beta gamma heterotrimer binds to the N terminus (NT) of type 5 AC (AC5). We now show that G beta gamma binds to the NT of a wide variety of AC isoforms. We hypothesized that G beta gamma/AC5 interactions involving inactive heterotrimer and G beta gamma stimulation of AC5 were separable events. Mutations of the G beta gamma "hotspot" show that this site is necessary for AC5 stimulation but not for interactions with the first 198 aa of AC5NT, which is a G protein scaffolding site. This contrasts with AC6, where the G beta gamma hotspot is required for both interactions with AC6NT and for stimulation of AC6. Additionally, the SIGK hotspot peptide disrupts G beta gamma regulation of AC isoforms 1, 2, and 6, but not AC5. G beta gamma also binds the C1/C2 catalytic domains of AC5 and AC6. Finally, cellular interactions with full-length AC5 depend on multiple sites on G beta gamma. This suggests an isoform-specific mechanism in which bound Gbg at the AC5NT is ideally situated for spatiotemporal control of AC5. We propose G beta gamma regulation of AC involves multiple binding events, and the role of the AC NT for mechanisms of regulation by heterotrimeric G protein subunits is isoform-specific.