Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA.
Cell. 2010 Dec 10;143(6):966-77. doi: 10.1016/j.cell.2010.11.028.
Phospholipid-binding modules such as PH, C1, and C2 domains play crucial roles in location-dependent regulation of many protein kinases. Here, we identify the KA1 domain (kinase associated-1 domain), found at the C terminus of yeast septin-associated kinases (Kcc4p, Gin4p, and Hsl1p) and human MARK/PAR1 kinases, as a membrane association domain that binds acidic phospholipids. Membrane localization of isolated KA1 domains depends on phosphatidylserine. Using X-ray crystallography, we identified a structurally conserved binding site for anionic phospholipids in KA1 domains from Kcc4p and MARK1. Mutating this site impairs membrane association of both KA1 domains and intact proteins and reveals the importance of phosphatidylserine for bud neck localization of yeast Kcc4p. Our data suggest that KA1 domains contribute to "coincidence detection," allowing kinases to bind other regulators (such as septins) only at the membrane surface. These findings have important implications for understanding MARK/PAR1 kinases, which are implicated in Alzheimer's disease, cancer, and autism.
磷脂结合模块，如 PH、C1 和 C2 结构域，在许多蛋白激酶的位置依赖调节中发挥关键作用。在这里，我们确定了 KA1 结构域（激酶相关-1 结构域），它位于酵母隔膜相关激酶（Kcc4p、Gin4p 和 Hsl1p）和人类 MARK/PAR1 激酶的 C 末端，是一个与膜结合的结构域，能够与酸性磷脂结合。分离的 KA1 结构域的膜定位依赖于磷脂酰丝氨酸。通过 X 射线晶体学，我们在 Kcc4p 和 MARK1 的 KA1 结构域中鉴定出一个结构保守的阴离子磷脂结合位点。突变该位点会损害 KA1 结构域和完整蛋白的膜结合，同时揭示了磷脂酰丝氨酸对于酵母 Kcc4p 在芽颈处定位的重要性。我们的数据表明，KA1 结构域有助于“偶联检测”，使激酶只能在膜表面与其他调节剂（如 septin）结合。这些发现对于理解 MARK/PAR1 激酶具有重要意义，MARK/PAR1 激酶与阿尔茨海默病、癌症和自闭症有关。
