Laboratory for Cell Biology, The First Affiliated Hospital, Zhengzhou University, Henan 450052, China; Henan Province Academician & Expert workstation, Clinical Research Centre, People's Hospital of Zhengzhou, China.
Res Microbiol. 2013 Dec;164(10):1028-34. doi: 10.1016/j.resmic.2013.08.009. Epub 2013 Sep 12.
Although the C-terminal motor and the N-terminal myosin-like domains of KCBP in Dunaliella salina (DsKCBP) are implicated in interaction with the microtubules, its microtubule binding property has not been addressed. It has been shown that several calmodulin isoforms suppress the microtubule binding activity of KCBP, but whether the calmodulin-like protein (CLP) has this ability remains unknown. The results of our previous study showed that there are two microtubule binding sites in DsKCBP, motor domain at the C-terminus and MyTH4-FREM at the N-terminus. In the present study, MyTH4, without the companion of FERM, was identified as the minimal domain responsible for interaction with the microtubules in the N-terminal of DsKCBP. CLP interacted with the calmodulin-binding domain of DsKCBP in the presence of Ca(2+), and inhibited the microtubule-binding activity of motor domain but not MyTH4 domain. Furthermore, MyTH4 domain in the N-terminus of DsKCBP was responsible for binding to the microtubules, and had 10-fold weaker affinity to the microtubules than the motor domain.
尽管来自盐生杜氏藻（Dunaliella salina）的 KCBP 的 C 端马达和 N 端肌球蛋白样结构域与微管相互作用有关，但它的微管结合特性尚未得到解决。已经表明，几种钙调蛋白同工型抑制 KCBP 的微管结合活性，但钙调蛋白样蛋白（CLP）是否具有这种能力尚不清楚。我们之前的研究结果表明，DsKCBP 中有两个微管结合位点，C 端的马达结构域和 N 端的 MyTH4-FREM。在本研究中，没有 FERM 伴侣的 MyTH4 被确定为负责与 DsKCBP N 端微管相互作用的最小结构域。CLP 在 Ca2+存在下与 DsKCBP 的钙调蛋白结合域相互作用，并抑制马达结构域的微管结合活性，但不抑制 MyTH4 结构域。此外，DsKCBP N 端的 MyTH4 结构域负责与微管结合，与微管的亲和力比马达结构域弱 10 倍。
