Komatsu Tomoya, Matsui Ikuo, Yokoyama Hideshi
Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, Japan.
Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8566, Japan.
Biochem Biophys Rep. 2022 Nov 11;32:101384. doi: 10.1016/j.bbrep.2022.101384. eCollection 2022 Dec.
Stomatin is a major integral membrane protein in human erythrocytes. In a form of hemolytic anemia known as hereditary stomatocytosis, stomatin is deficient in the erythrocyte membrane due to mis-trafficking. It is a member of stomatin, prohibitin, flotillin, and HflK/C (SPFH) domain proteins, and SPFH proteins could function as membrane-bound oligomeric scaffolding proteins in lipid rafts. The previously determined structure of the SPFH domain of (Ph) stomatin formed a trimer, whereas that of mouse stomatin formed a dimer. To elucidate the difference of oligomerization state, structural and chromatographic analyses using Ph stomatin were performed, and the key residues were suggested to determine whether SPFH domains form dimers or trimers. From gel-filtration analyses, PhStom (56-234) formed a trimer or tetramer, whereas PhStom (63-234) and PhStom (56-234) K59S formed a dimer. The residues 56-62, particularly Lys59, were involved in trimerization. Based on the crystal structure of PhStom (63-234), it formed a banana-shaped dimer, as observed in mouse stomatin. Thus, residues 162-168 are involved in dimerization. This study provides important insight into the molecular function and oligomerization state of stomatin.
血影蛋白是人类红细胞中的一种主要整合膜蛋白。在一种称为遗传性口形红细胞增多症的溶血性贫血中，由于运输错误，血影蛋白在红细胞膜中缺乏。它是血影蛋白、抑制素、弗洛蒂林和HflK/C（SPFH）结构域蛋白家族的成员，SPFH蛋白可作为脂筏中膜结合的寡聚支架蛋白发挥作用。先前确定的（Ph）血影蛋白的SPFH结构域形成三聚体，而小鼠血影蛋白的SPFH结构域形成二聚体。为了阐明寡聚化状态的差异，对Ph血影蛋白进行了结构和色谱分析，并提出了决定SPFH结构域是形成二聚体还是三聚体的关键残基。从凝胶过滤分析来看，PhStom（56 - 234）形成三聚体或四聚体，而PhStom（63 - 234）和PhStom（56 - 234）K59S形成二聚体。56 - 62位残基，特别是赖氨酸59，参与三聚化。基于PhStom（63 - 234）的晶体结构，它形成了如在小鼠血影蛋白中观察到的香蕉形二聚体。因此，162 - 168位残基参与二聚化。本研究为血影蛋白的分子功能和寡聚化状态提供了重要见解。
