CSIR-Centre for Cellular and Molecular Biology (CCMB), Hyderabad, India.
CSIR-Centre for Cellular and Molecular Biology (CCMB), Hyderabad, India.
Biochem Biophys Res Commun. 2021 Sep 17;570:67-73. doi: 10.1016/j.bbrc.2021.07.018. Epub 2021 Jul 14.
Centrin-1, a Ca sensor protein of the centrin family is a crucial player for cell division in eukaryotes and plays a key role in the microtubule organising centre. Despite being regarded as a calcium sensor with a matched structure to calmodulin/troponin C, the protein undergoes mild changes in conformation and binds Ca with moderate affinity. We present an in-depth analysis of the Ca sensing by individual EF-hand motifs of centrin-1 and address unsolved questions of the rationales for moderate affinity and conformational transitions of the protein. Employing the more sensitive approach of Trp scanning of individual EF-hand motif, we have undertaken an exhaustive investigation of Ca binding to individual EF-hand motifs, named EF1 to EF4. All four EF-hand motifs of centrin-1 are structural as all of them bind both Ca and Mg. EF1 and EF4 are the most flexible sites as they undergo drastic conformational changes following Ca binding, whereas EF3 responds to Ca minimally. On the other hand, EF2 moves towards the protein surface upon binding Ca. The independent filling mode of Ca to EF-hand motifs and lack of intermotif communication explain the lack of cooperativity of binding, thus constraining centrin-1 to a moderate affinity binding protein. Thus, centrin-1 is distinct from other calcium sensors such as calmodulin.
中心体蛋白-1（Centrin-1）是中心体家族的钙传感器蛋白，在真核细胞的细胞分裂中起着至关重要的作用，并在微管组织中心发挥关键作用。尽管它被认为是一种具有与钙调蛋白/肌钙蛋白 C 匹配结构的钙传感器，但该蛋白的构象仅发生轻微变化，并以中等亲和力结合 Ca。我们对中心体蛋白-1 的单个 EF 手模体的钙感应进行了深入分析，并解决了该蛋白中等亲和力和构象转变的合理性方面尚未解决的问题。我们采用单个 EF 手模体色氨酸扫描的更敏感方法，对 EF1 到 EF4 这四个中心体蛋白-1 的 EF 手模体的 Ca 结合进行了详尽的研究。中心体蛋白-1 的所有四个 EF 手模体都是结构模体，因为它们都结合 Ca 和 Mg。EF1 和 EF4 是最灵活的位点，因为它们在结合 Ca 后会发生剧烈的构象变化，而 EF3 对 Ca 的响应最小。另一方面，EF2 在结合 Ca 时会向蛋白质表面移动。EF 手模体对 Ca 的独立填充模式和模间缺乏通讯解释了结合缺乏协同性，从而限制了中心体蛋白-1 成为一种中等亲和力的结合蛋白。因此，中心体蛋白-1 与钙调蛋白等其他钙传感器不同。
