Chen Kai-En, Tillu Vikas A, Gopaldass Navin, Chowdhury Sudeshna Roy, Leneva Natalya, Kovtun Oleksiy, Ruan Juanfang, Guo Qian, Ariotti Nicholas, Mayer Andreas, Collins Brett M
Institute for Molecular Bioscience, the University of Queensland, St Lucia, QLD, Australia.
Department of Immunobiology, University of Lausanne, Epalinges, Switzerland.
Nat Commun. 2025 Apr 15;16(1):3568. doi: 10.1038/s41467-025-58846-8.
Retromer mediates endosomal retrieval of transmembrane proteins in all eukaryotes and was first discovered in yeast in complex with the Vps5 and Vps17 sorting nexins (SNXs). Cryoelectron tomography (cryoET) studies of Retromer-Vps5 revealed a pseudo-helical coat on membrane tubules where dimers of the Vps26 subunit bind Vps5 membrane-proximal domains. However, the Vps29 subunit is also required for Vps5-Vps17 association despite being far from the membrane. Here, we show that Vps5 binds both Vps29 and Vps35 subunits through its unstructured N-terminal domain. A Pro-Leu (PL) motif in Vps5 binds Vps29 and is required for association with Retromer on membrane tubules in vitro, and for the proper recycling of the Vps10 cargo in Saccharomyces cerevisiae. CryoET of Retromer tubules with Vps5-Vps17 heterodimers show a similar architecture to the coat with Vps5-Vps5 homodimers, however, the spatial relationship between Retromer units is highly restricted, likely due to more limited orientations for docking. These results provide mechanistic insights into how Retromer and SNX-BAR association has evolved across species.
Retromer介导所有真核生物中跨膜蛋白的内体回收,最初是在酵母中与Vps5和Vps17分选连接蛋白(SNXs)形成复合物时被发现的。对Retromer-Vps5的冷冻电子断层扫描(cryoET)研究揭示了膜小管上的假螺旋衣被,其中Vps26亚基的二聚体结合Vps5的膜近端结构域。然而,尽管Vps29亚基远离膜,但它对于Vps5-Vps17的结合也是必需的。在这里,我们表明Vps5通过其无结构的N端结构域与Vps29和Vps35亚基结合。Vps5中的一个脯氨酸-亮氨酸(PL)基序结合Vps29,是体外与膜小管上的Retromer结合以及酿酒酵母中Vps10货物正确循环所必需的。带有Vps5-Vps17异二聚体的Retromer小管的cryoET显示出与带有Vps5-Vps5同二聚体的衣被相似的结构,然而,Retromer单元之间的空间关系受到高度限制,这可能是由于对接方向更有限。这些结果为Retromer和SNX-BAR结合在物种间如何进化提供了机制上的见解。