两种模式酵母中可分解丙酮醛的 GLO3的特性及鉴定

摘要

GLO3是一种不依赖辅助因子就可分解丙酮醛的酶，有研究表明大肠杆菌的EcHsp31和人的HsDJ-1均属于这种GLO3。丙酮醛是细胞糖酵解过程中产生的一种有毒的副产物，乙二醛酶Ⅰ（ GLO1）和乙二醛酶Ⅱ（GLO2）在谷胱甘肽（GSH）的辅助下可以降解细胞内丙酮醛，乙二醛酶Ⅲ（GLO3）不需要GSH的辅助可以直接降解MG。研究真菌的GLO3降解丙酮醛的机制，对认识和研究因丙酮醛引起的疾病具有重要的指导意义。研究表明，真菌中GLO3同源蛋白十分复杂，Hsp31在真菌中广泛存在，DJ-1只在部分真菌中存在，进化树结果支持GLO3的同源蛋白Hsp31和DJ-1是一种趋同进化。对模式真菌酿酒酵母的ScHsp31和裂殖酵母SpDJ-1进行GLO3的酶活测定和HPLC产物检测表明，这两种蛋白均具有GLO3的特性。%Most recently, a GSH-independent glyoxalase pathway was identified in Escherichia coli, Caenorhabditis elegans, mice and humans.Mechanisms of MG detoxicification include the glutathione (GSH)-dependent pathway consisting of glyoxalase Ⅰ ( GLO1 ) and glyoxalase Ⅱ ( GLO2 ) , and GSH-independent pathway catalyzed by glyoxalase Ⅲ (GLO3).E.coli Hsp31 and metazoan DJ-1 proteins, belong to two different subfamilies of the Hsp31/DJ-1 superfamily, have been demonstrated to have GLO 3 activity.However, genes encoding GLO3 have not been reported in fungi .We performed a systematic survey of homologs of Hsp 31 and DJ-1 in fungi.We found that Hsp31 proteins are widely distributed among different fungal groups , whereas DJ-1 proteins have a very limited distribution in fungi .Phylogenetic analysis of these sequences revealed that fungal Hsp 31 and DJ-1 proteins form two distinct monophyletic groups , and that fungal Hsp 31 proteins can clearly be divided into different classes .One Saccharomyces cerevisiae Hsp31 protein ( ScHsp31 ) and Schizosaccharomyces pombe DJ-1 ( SpDJ-1 ) have GLO3 activity in vitro.Our results revealed that fungal homologs of the Hsp 31/DJ-1 superfamily could be GLO3, which may have some roles in protecting cells from MG toxicity .Our results also support the view that GLO 3 activity likely evolved through convergent evolution .