University of Southern Denmark, PHYLIFE: Physical Life Science, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark.
Danish Cancer Society, Danish Cancer Society Research Center, Copenhagen, Denmark.
Biophys J. 2023 Jul 25;122(14):3008-3017. doi: 10.1016/j.bpj.2023.04.002. Epub 2023 Apr 6.
The annexins are a family of Ca-dependent peripheral membrane proteins. Several annexins are implicated in plasma membrane repair and are overexpressed in cancer cells. Annexin A4 (ANXA4) and annexin A5 (ANXA5) form trimers that induce high curvature on a membrane surface, a phenomenon deemed to accelerate membrane repair. Despite being highly homologous to ANXA4, annexin A3 (ANXA3) does not form trimers on the membrane surface. Using molecular dynamics simulations, we have reverse engineered an ANXA3-mutant to trimerize on the surface of the membrane and induce high curvature reminiscent of ANXA4. In addition, atomic force microscopy images show that, like ANXA4, the engineered protein forms crystalline arrays on a supported lipid membrane. Despite the trimer-forming and curvature-inducing properties of the engineered ANXA3, it does not accumulate near a membrane lesion in laser-punctured cells and is unable to repair the lesion. Our investigation provides insights into the factors that drive annexin-mediated membrane repair and shows that the membrane-repairing property of trimer-forming annexins also necessitates high membrane binding affinity, other than trimer formation and induction of negative membrane curvature.
膜联蛋白是一类依赖 Ca2+的外周膜蛋白家族。几种膜联蛋白参与质膜修复，并且在癌细胞中过度表达。膜联蛋白 A4（ANXA4）和膜联蛋白 A5（ANXA5）形成三聚体，在膜表面诱导高曲率，这一现象被认为可以加速膜修复。尽管膜联蛋白 A3（ANXA3）与 ANXA4 高度同源，但它不会在膜表面形成三聚体。通过分子动力学模拟，我们对 ANXA3 进行了反向工程改造，使其在膜表面三聚体化并诱导类似于 ANXA4 的高曲率。此外，原子力显微镜图像显示，与 ANXA4 类似，该工程蛋白在支撑脂质膜上形成结晶阵列。尽管工程化的 ANXA3 具有三聚体形成和曲率诱导特性，但它不会在激光穿孔细胞中的膜损伤附近积累，并且无法修复损伤。我们的研究提供了对驱动膜联蛋白介导的膜修复的因素的深入了解，并表明三聚体形成的膜联蛋白的膜修复特性除了三聚体形成和诱导负膜曲率之外，还需要高的膜结合亲和力。
