Kern Maximilian, Fernandez-Sáiz Vanesa, Schäfer Zasie, Buchberger Alexander
Max Planck Institute of Biochemistry, Department of Molecular Cell Biology, Am Klopferspitz 18, 82152 Martinsried, Germany.
Biochem Biophys Res Commun. 2009 Mar 6;380(2):303-7. doi: 10.1016/j.bbrc.2009.01.076. Epub 2009 Jan 25.
The chaperone-related p97 protein plays a central role in various cellular processes involving the ubiquitin-proteasome system. The diverse functions of p97 are controlled by a large number of cofactors that recruit specific substrates or influence their ubiquitylation state. Many cofactors bind through a UBX or PUB domain, two major p97 binding modules. However, the recently identified UBXD1 cofactor possesses both domains. To elucidate the molecular basis underlying the interaction between UBXD1 and p97, we analyzed the contribution of both domains to p97 binding biochemically and in living cells. The PUB domain mediated robust binding to the carboxy-terminus of p97, while the UBX domain did not contribute to p97 binding. Importantly, we identified an additional p97 binding site in UBXD1 that competed with the p47 cofactor for binding to the N domain of p97. This novel, bipartite binding mode suggests that UBXD1 could be an efficient regulator of p97 cofactor interactions.
伴侣蛋白相关的p97蛋白在涉及泛素-蛋白酶体系统的各种细胞过程中发挥核心作用。p97的多种功能由大量辅助因子控制，这些辅助因子招募特定底物或影响其泛素化状态。许多辅助因子通过UBX或PUB结构域结合，这是两个主要的p97结合模块。然而，最近鉴定出的UBXD1辅助因子同时拥有这两个结构域。为了阐明UBXD1与p97之间相互作用的分子基础，我们从生化和活细胞水平分析了这两个结构域对p97结合的贡献。PUB结构域介导与p97羧基末端的强结合，而UBX结构域对p97结合没有贡献。重要的是，我们在UBXD1中鉴定出另一个p97结合位点，该位点与p47辅助因子竞争结合p97的N结构域。这种新的双位点结合模式表明UBXD1可能是p97辅助因子相互作用的有效调节因子。
