Mutation and mutagenesis of thiol peroxidase of Escherichia coli and a new type of thiol peroxidase family
Mutation and mutagenesis of thiol peroxidase of Escherichia coli and a new type of thiol peroxidase family
复制标题
DOI：
10.1128/jb.178.19.5610-5614.1996
复制
发表时间：
1996-10-01
影响因子：
3.2
通讯作者：
Kim, IH
中科院分区：
文献类型：
--
作者：
Cha, MK;Kim, HK;Kim, IH
先前已经报道了来自大肠杆菌的一种新的硫氧还蛋白连接的巯基过氧化物酶（Px）（M. K. Cha，H. K.金和我H. Kim，J.Biol.Chem.270：28635-28641，1995）。在尝试进行的生理和生化特性的硫醇Px，硫醇Px的突变体（tpx）和功能残基突变体的硫醇Px的生产，tpx突变体是活的有氧培养，但比野生型细胞生长缓慢，生长速度的差异变得更加明显时，氧化应激诱导剂，如过氧化物和百草枯，添加到培养物。tpx突变体在氧化胁迫下的存活率远低于野生型，在需氧条件下生长的tpx突变体对百草枯的反应能力是野生型的6倍，推测的巯基Px的氨基酸序列与流感嗜血杆菌的蛋白序列有42 - 72%的同源性（ToxR调节子）、霍乱弧菌（ToxR调节子）和三种链球菌（coaggregation-mediated adhesins），表明它们都属于一个新的巯基Px家族。coli的巯基Px是完全保守的，用丝氨酸取代该半胱氨酸后，Px活性完全丧失。coli巯基Px，具有功能性半胱氨酸残基，在体内作为过氧化物酶发挥功能。
A novel thioredoxin-linked thiol peroxidase (Px) from Escherichia coli has been reported previously (M. K. Cha, H. K. Kim, and I. H. Kim, J. Biol. Chem. 270:28635-28641, 1995). In an attempt to perform physiological and biochemical characterizations of the thiol Px, a thiol Px null (tpx) mutant and a functional-residue mutant of thiol Px were produced, The tpx mutant was viable in aerobic culture but grew more slowly than the wild-type cells, The difference in growth rate became more pronounced when oxidative-stress-inducing reagents, such as peroxides and paraquat, were added to the cultures. The viability of the individual tpx mutant under oxidative stress was much lower than that of wild-type cells, tpx mutants growing aerobically respond to paraquat with a sixfold greater induction of Mn-superoxide dismutase than that of the wild-type cells, The deduced amino acid sequence of the thiol Px was found to be from 42 to 72% identical to the sequences of proteins from Haemophilus influenzae (ToxR regulon), Vibrio cholerae (ToxR regulon), and three kinds of streptococci (coaggregation-mediating adhesins), suggesting that they all belong to a new thiol Px family, Alignment of the amino acid sequences of the thiol Px family members showed that one cysteine, which corresponds to Cys-94 in E. coli thiol Px, is perfectly conserved, The substitution of serine for this cysteine residue resulted in complete loss of Px activity, These results suggest that the members of the thiol Px family, including E. coli thiol Px, have a functional cysteine residue and function in vivo as peroxidases.