Enhancement of ABL Kinase Catalytic Efficiency by a Direct Binding Regulator Is Independent of Other Regulatory Mechanisms
Enhancement of ABL Kinase Catalytic Efficiency by a Direct Binding Regulator Is Independent of Other Regulatory Mechanisms
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DOI：
10.1074/jbc.m804002200
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发表时间：
2008-11-14
影响因子：
4.8
通讯作者：
Colicelli, John
中科院分区：
文献类型：
--
作者：
Cao, Xiaoqing;Tanis, Keith Q.;Colicelli, John
ABL家族酪氨酸激酶受自身抑制和磷酸化机制的严格调节。这些激酶通过涉及SH 3和SH 2结构域的分子内相互作用保持非活性构象。RIN 1是RAS的下游效应子，与ABL SH 3和SH 2结构域结合并刺激ABL酪氨酸激酶活性。RIN 1与ABL 2激酶的结合导致K-m大幅降低，V-max向ABL共有底物肽小幅增加。酶效率（k（cat）/K-m）通过RIN 1增加超过5倍。此外，RIN 1强烈增强ABL介导的CRK、PSTPIP 1和DOK 1的磷酸化，所有这些都建立了ABL底物，但具有独特的蛋白质结构和不同的靶序列。重要的是，RIN 1介导的ABL激酶活性刺激不依赖于SRC介导的磷酸化激活。RIN 1增加了ABL 1和ABL 2的激酶活性，并且这发生在SH 3-SH 2-酪氨酸激酶结构域核心之外存在或不存在ABL调节结构域的情况下。我们进一步证明了与广泛耐药相关的催化位点突变ABL 1（T315 I）仍然对RIN 1的刺激有反应。这些发现与变构激酶激活机制一致，通过该机制，RIN 1结合通过减轻自身抑制促进更易接近的ABL催化位点。因此，直接破坏RIN 1结合可能是抑制正常和致癌ABL活性的有用策略，包括混淆当前治疗策略的耐药突变体。通过去阻遏的刺激可能适用于许多其他的酪氨酸激酶的自抑制耦合SH 3和SH 2结构域。
ABL family tyrosine kinases are tightly regulated by autoinhibition and phosphorylation mechanisms. These kinases maintain an inactive conformation through intramolecular interactions involving SH3 and SH2 domains. RIN1, a downstream effector of RAS, binds to the ABL SH3 and SH2 domains and stimulates ABL tyrosine kinase activity. RIN1 binding to the ABL2 kinase resulted in a large decrease in K-m and a small increase in V-max toward an ABL consensus substrate peptide. The enzyme efficiency (k(cat)/K-m) was increased more than 5-fold by RIN1. In addition, RIN1 strongly enhanced ABL-mediated phosphorylation of CRK, PSTPIP1, and DOK1, all established ABL substrates but with unique protein structures and distinct target sequences. Importantly RIN1-mediated stimulation of ABL kinase activity was independent of activation by SRC-mediated phosphorylation. RIN1 increased the kinase activity of both ABL1 and ABL2, and this occurred in the presence or absence of ABL regulatory domains outside the SH3-SH2-tyrosine kinase domain core. We further demonstrate that a catalytic site mutation associated with broad drug resistance, ABL1(T315I), remains responsive to stimulation by RIN1. These findings are consistent with an allosteric kinase activation mechanism by which RIN1 binding promotes a more accessible ABL catalytic site through relief of autoinhibition. Direct disruption of RIN1 binding may therefore be a useful strategy to suppress the activity of normal and oncogenic ABL, including inhibitor-resistant mutants that confound current therapeutic strategies. Stimulation through derepression may be applicable to many other tyrosine kinases autoinhibited by coupled SH3 and SH2 domains.