Department of Chemical and Biological Engineering, University of Colorado-Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303, United States.
Biochemistry. 2021 Feb 2;60(4):254-258. doi: 10.1021/acs.biochem.0c00841. Epub 2021 Jan 15.
Allosteric regulation enables dynamic adjustments to protein function that permit tight control over cellular biochemistry. Discrepancies in the allosteric systems of related proteins can thus reveal important differences in their susceptibilities to influential stimuli (e.g., allosteric ligands, mutations, or post-translational modifications). This study uses an optogenetic actuator as a tool to compare the allosteric systems of two structurally related regulatory proteins: protein tyrosine phosphatase 1B (PTP1B) and T-cell protein tyrosine phosphatase (TCPTP). It begins with an interesting observation: The fusion of a protein light switch to the allosterically influential α7 helix of PTP1B permits optical modulation of its catalytic activity, but a similar fusion to TCPTP does not. A subsequent analysis of different PTP chimeras shows that replacing regions of TCPTP with homologous regions from PTP1B can enhance photocontrol; as TCPTP becomes more "PTP1B-like", its photosensitivity increases. Interestingly, the structural changes required for photocontrol also enhance the sensitivity of TCPTP to other allosteric inputs, notably, an allosteric inhibitor and a newly reported activating mutation. Our findings indicate that the allosteric functionality of the α7 helix of PTP1B is not conserved across the PTP family and highlight residues necessary to transfer this functionality to other PTPs. More broadly, our results suggest that simple gene fusion events can strengthen allosteric communication within individual protein domains and describe an intriguing application for optogenetic actuators as structural probes-a sort of physically disruptive "ratchet"-for studying protein allostery.
变构调节使蛋白质功能能够进行动态调整，从而可以对细胞生物化学进行紧密控制。因此，相关蛋白质的变构系统的差异可以揭示它们对有影响力的刺激（例如变构配体、突变或翻译后修饰）的敏感性的重要差异。本研究使用光遗传学致动器作为工具比较两种结构相关的调节蛋白的变构系统：蛋白酪氨酸磷酸酶 1B（PTP1B）和 T 细胞蛋白酪氨酸磷酸酶（TCPTP）。它首先观察到一个有趣的现象：将蛋白质光开关融合到 PTP1B 的变构影响的 α7 螺旋中，可以使其催化活性得到光调节，但类似的融合到 TCPTP 则不行。对不同的 PTP 嵌合体的后续分析表明，用 PTP1B 的同源区域替换 TCPTP 的区域可以增强光控；随着 TCPTP 变得更“像 PTP1B”，其光敏性增加。有趣的是，光控所需的结构变化也增强了 TCPTP 对其他变构输入的敏感性，特别是变构抑制剂和新报道的激活突变。我们的研究结果表明，PTP1B 的 α7 螺旋的变构功能在整个 PTP 家族中没有保守性，并突出了将这种功能转移到其他 PTP 所需的残基。更广泛地说，我们的结果表明，简单的基因融合事件可以增强单个蛋白质结构域内的变构通讯，并描述了光遗传学致动器作为结构探针的一种有趣应用，即一种物理上的破坏性“棘轮”，用于研究蛋白质变构。
