Kashima Toma, Akama Megumi, Wakinaka Takura, Arakawa Takatoshi, Ashida Hisashi, Fushinobu Shinya
1 Department of Biotechnology, The University of Tokyo.
2 Manufacturing Division, Yamasa Corporation.
J Appl Glycosci (1999). 2024 Aug 20;71(3):81-90. doi: 10.5458/jag.jag.JAG-2024_0005. eCollection 2024.
To overcome incompatibility issues and increase the possibility of blood transfusion, technologies that enable efficient conversion of A- and B-type red blood cells to the universal donor O-type is desirable. Although several blood type-converting enzymes have been identified, detailed understanding about their molecular functions is limited. α-Galactosidase from JCM 1254 (AgaBb), belonging to glycoside hydrolase (GH) 110 subfamily A, specifically acts on blood group B antigen. Here we present the crystal structure of AgaBb, including the catalytic GH110 domain and part of the C-terminal uncharacterized regions. Based on this structure, we deduced a possible binding mechanism of blood group B antigen to the active site. Site-directed mutagenesis confirmed that R270 and E380 recognize the fucose moiety in the B antigen. Thermal shift assay revealed that the C-terminal uncharacterized region significantly contributes to protein stability. This region is shared only among GH110 enzymes from and some species. The elucidation of the molecular basis for the specific recognition of blood group B antigen is expected to lead to the practical application of blood group conversion enzymes in the future.
为了克服不相容问题并增加输血的可能性，能够将A型和B型红细胞高效转化为通用供体O型的技术是很有必要的。尽管已经鉴定出几种血型转换酶，但对其分子功能的详细了解仍然有限。来自日本微生物菌种保藏中心1254株（AgaBb）的α-半乳糖苷酶属于糖苷水解酶（GH）110亚家族A，它特异性作用于B血型抗原。在此，我们展示了AgaBb的晶体结构，包括催化性的GH110结构域和部分C末端未表征区域。基于此结构，我们推导了B血型抗原与活性位点的可能结合机制。定点诱变证实R270和E380识别B抗原中的岩藻糖部分。热迁移分析表明C末端未表征区域对蛋白质稳定性有显著贡献。该区域仅在来自某些物种的GH110酶中共享。对B血型抗原特异性识别的分子基础的阐明有望在未来实现血型转换酶的实际应用。
