Pharmazeutisches Institut der Universität Tübingen, Tübingen, Germany; Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany.
Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany.
Cell Signal. 2020 Apr;68:109538. doi: 10.1016/j.cellsig.2020.109538. Epub 2020 Jan 10.
Mammalian adenylate cyclases (ACs) are pseudoheterodimers with dissimilar hexahelical membrane-anchors, isoform-specifically conserved for more than half a billion years. We exchanged both membrane anchors of the AC isoform 2 by the quorum-sensing receptor from Vibrio harveyi, CqsS, which has a ligand, Cholera-Autoinducer-1 (CAI-1). In the chimera, AC activity was stimulated by Gsα, CAI-1 had no effect. Surprisingly, CAI-1 inhibited Gsα stimulation. We report that Gsα stimulation of human AC isoforms 2, 3, 5, and 9 expressed in Sf9 cells is inhibited by serum as is AC activity in membranes isolated from rat brain cortex. AC2 activation by forskolin or forskolin/Gsα was similarly inhibited. Obviously, serum contains as yet unidentified factors affecting AC activity. The data establish a linkage in ACs, in which the membrane anchors, as receptors, transduce extracellular signals to the cytosolic catalytic dimer. A mechanistic three state model of AC regulation is presented compatible with all known regulatory inputs into mammalian ACs. The data allow designating the membrane anchors of mammalian ACs as orphan receptors, and establish a new level of AC regulation.
哺乳动物腺苷酸环化酶（ACs）是具有不同六螺旋膜锚的伪异源二聚体，其异构体特异性保守了超过 5 亿年。我们通过群体感应受体 Vibrio harveyi 的 CqsS 交换了 AC 同工型 2 的两个膜锚，CqsS 有一个配体霍乱毒素自动诱导物-1（CAI-1）。在嵌合体中，AC 活性被 Gsα 刺激，CAI-1 没有影响。令人惊讶的是，CAI-1 抑制了 Gsα 的刺激。我们报告说，在 Sf9 细胞中表达的人 AC 同工型 2、3、5 和 9 被血清抑制，大鼠大脑皮质分离的膜中的 AC 活性也被抑制。 forskolin 或 forskolin/Gsα 对 AC2 的激活也受到类似的抑制。显然，血清中含有影响 AC 活性的未知因素。这些数据建立了 AC 之间的联系，其中膜锚作为受体，将细胞外信号转导到胞质催化二聚体。提出了一种与所有已知调节输入到哺乳动物 AC 的机制三态模型一致的 AC 调节机制。这些数据允许将哺乳动物 AC 的膜锚指定为孤儿受体，并建立了新的 AC 调节水平。
