收稿日期: 2021-07-13
网络出版日期: 2021-12-25
基金资助
国家自然科学基金青年项目(82000183)
AwB subtype caused by a novel ABO *A allele and its molecular mechanisms
Received date: 2021-07-13
Online published: 2021-12-25
目的: 对1例血型AwB亚型个体进行血清学鉴定和基因检测,探讨血型AwB亚型发生的分子学机制。方法: 使用标准血清学实验方法对1例血型AwB亚型个体进行ABO血清学定型,并对其ABO基因7个外显子及其侧翼序列进行PCR扩增、基因克隆和测序分析;采用Chimera软件进行ABO基因编码糖基转移A酶（glycosyl transferase A,GTA）突变体构建,用PyMOL软件作图并进行分析。结果: 血清学鉴定结果显示该个体为AwB亚型。DNA克隆和基因测序分析结果显示,先证者的A基因为一个A1.02与A3.03顺式表达的等位基因,基因型为ABO*Avar/B.01。在国际输血协会数据库中查询,发现该变异A等位基应为一种新等位基因,其存在c.467C>T和c.838C>T错义突变,导致GTA发生p.P156L和p.L280F氨基酸置换。对GTA空间结构进行分析后认为,导致该表型的p.L280F未导致GTA蛋白整体结构的改变,但改变了GTA 280位氨基酸与周围氨基酸残基的氢键网络,导致局部构象改变。结论: 本研究发现了1个新的A等位基因导致的AwB亚型,其形成机制为A1.02等位基因编码的糖基转移酶存在p.L280F突变,可能改变了邻近氨基酸间的作用力,从而导致A酶活性减弱,在与B等位基因共表达时形成AwB亚型。
周璐, 雷航, 洪叶, 金爽, 董永勤, 王学锋, 蔡晓红 . 一个新的ABO*A等位基因导致的AwB亚型及其分子机制研究[J]. 诊断学理论与实践, 2021 , 20(06) : 547 -551 . DOI: 10.16150/j.1671-2870.2021.06.006
Objective: To investigate the molecular mechanism of AwB subtype by performing serological and gene detection in a Chinese individual. Methods: One case of AwB subtype was determined by ABO serology using standard serological method, and 7 exons of ABO gene and their flanks were amplified by PCR, and then cloned and sequenced. Glycosyl Transferase A (GTA) mutants were constructed by Chimera software, and was mapped and analyzed by PyMOL software. Results: Serological identification showed that this individual had AwB subtype. DNA cloning and gene sequen-cing analysis showed that the A gene from the proband was A cis-expressed allele of A1.02 and A3.03, and the genotype was ABO*Avar/B.01. In the ISBT database, the A allele of this variant should be a novel allele, with missense mutations in c. 467C>T and c. 838C>T, which could result in p.P.156L and p.L.280F amino acid replacement in GTA. Analysis of the spatial structure of GTA showed, p.L280F resulted in the phenotypes, and did not lead to changes in the overall structure of GTA proteins, which altered the hydrogen bond network between amino acid 280 and surrounding amino acid residues, resulting in local conformation changes. Conclusions: AwB subtype caused by a novel A allele-is reported for the first time. The formation mechanism may be as follows: p.L280F mutations in glycosyltransferases encoded by the A1.02 allele alter the interactions between adjacent amino acids, resulting in reduced activity of the A enzyme,and AwB subtype occurs when co-expressing with the B allele.
Key words： ABO blood group system; AwB subtype; Genetic mutation
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