Abstract: Objective To identify a rare cisAB subtype by immunoserology and PacBio third-generation sequencing technology, and explore the molecular mechanism of amino acid mutations in cisAB glycosyltransferase by molecular docking. Methods The ABO phenotype was identified by immunoserological method, and the genotype was identified by three generation sequencing technology. The homologous modeling and molecular docking of cisAB01 glycosyltransferase were used to explore the structural changes of the glycosyltransferase after key amino acid mutations. Results The serological phenotype was AB. The gene sequencing showed that the genotype was cisAB.01/O.01.02. Homology modeling and molecular docking showed that p.Pro156Leu and p.Gly268Ala mutation of cisAB01 glycosyltransferase alter the spatial structure of the binding groove of catalytic active center. Conclusion The p.Pro156Leu and p.Gly268Ala mutation are key sites for the bifunctional activity of cisAB01 glycosyltransferase．

Key words: cisAB subtype, PacBio third-generation sequencing technology, Homology modeling, Molecular mechanism, Molecular docking