MS5 is a meiosis-related protein belonging to the Brassicaceae-specific domain of unknown function family and characterized by the MS5 superfamily domain (MSD). In this study, we elucidated the three-dimensional crystal structure and potential biochemical function of the MSD. It was observed that the MSD adopts a cystatin-like fold, mainly consisting of a central α-helix and four- or five-stranded antiparallel β-sheets that wrap around it. However, unlike cystatins, which inhibit cysteine proteases, the MSD displayed allosteric activation of papain. We believe that our study provides insight into novel mechanisms of proteolytic enzyme regulation and may serve as a basis for functional studies of the MS5 family proteins in plants.

中文翻译：

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减数分裂相关蛋白 MS5 的结构分析揭示了半胱氨酸蛋白酶抑制剂样折叠的非经典木瓜蛋白酶增强

MS5 是一种减数分裂相关蛋白，属于未知功能家族的十字花科特定域，以 MS5 超家族域 (MSD) 为特征。在这项研究中，我们阐明了 MSD 的三维晶体结构和潜在的生化功能。据观察，MSD 采用类似胱抑素的折叠，主要由中央 α-螺旋和环绕它的四链或五链反平行 β-折叠组成。然而，与抑制半胱氨酸蛋白酶的胱抑素不同，MSD 显示木瓜蛋白酶的变构激活。我们相信我们的研究提供了对蛋白水解酶调控新机制的深入了解，并可作为植物中 MS5 家族蛋白功能研究的基础。