A novel zinc-dependent D-serine dehydratase from Saccharomyces cerevisiae
A novel zinc-dependent D-serine dehydratase from Saccharomyces cerevisiae
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DOI：
10.1042/bj20070642
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发表时间：
2008-01-15
影响因子：
4.1
通讯作者：
Yoshimura, Tohru
中科院分区：
文献类型：
--
作者：
Ito, Tomokazu;Hemmi, Hisashi;Yoshimura, Tohru
酿酒酵母YGL196W编码一种推定的蛋白质，该蛋白质尚未鉴定，但预测具有与细菌丙氨酸消旋酶的N-末端结构域相似的基序。在本研究中，我们发现YGL196W编码一种新的D-丝氨酸转氨酶，它属于一个不同的蛋白质家族从已知的细菌酶。从重组大肠杆菌细胞中纯化的酵母D-丝氨酸脱氢酶依赖于吡哆醛5'-磷酸和锌，并催化D-丝氨酸转化为丙酮酸和氨，Km和k（cat）值分别为0.39 mM和13.1 s（-1）。D-苏氨酸和β-Cl-D-丙氨酸也可作为底物，其催化效率约为100%。D-丝氨酸的含量分别为3%和2%。L-丝氨酸、L-苏氨酸和β-C1-L-丙氨酸作为底物是惰性的。原子吸收分析表明，该酶含有一个锌原子每个酶单体。酶对D-丝氨酸和D-苏氨酸的活性被EDTA处理降低，并通过添加Zn 2+恢复。Mg 2+、Mn 2+、Ca 2+、Ni 2+、Cu 2+、K+或Na+的回收率很低。相反，EDTA处理后保留了对β-Cl-D-丙氨酸的活性。这些结果表明，锌参与消除D-丝氨酸和D-苏氨酸的羟基。D-丝氨酸脱氢酶。酿酒酵母可能是真核生物D-丝氨酸脱氢酶的第一个例子，也是特异性锌依赖性吡哆醛酶的第一个例子。
YGL196W of Saccharomyces cerevisiae encodes a putative protein that is unidentified but is predicted to have a motif similar to that of the N-terminal domain of the bacterial alanine racemase. In the present study we found that YGL196W encodes a novel D-serine dehydratase, which belongs to a different protein family from that of the known bacterial enzyme. The yeast D-serine dehydratase purified from recombinant Escherichia coli cells depends on pyridoxal 5'-phosphate and zinc, and catalyses the conversion of D-serine into pyruvate and ammonia with the Km and k(cat), values of 0.39 mM and 13.1 s(-1) respectively. D-Threonine and beta-Cl-D-alanine also serve as substrates with catalytic efficiencies which are approx. 3 and 2 % of D-serine respectively. L-Serine, L-threonine and beta-Cl-L-alanine are inert as substrates. Atomic absorption analysis revealed that the enzyme contains one zinc atom per enzyme monomer. The enzyme activities toward D-serine and D-threonine were decreased by EDTA treatment and recovered by the addition of Zn2+. Little recovery was observed with Mg2+, Mn2+, Ca2+, Ni2+, Cu2+, K+ or Na+. In contrast, the activity towards beta-Cl-D-alanine was retained after EDTA treatment. These results suggest that zinc is involved in the elimination of the hydroxy group of D-serine and D-threonine. D-Serine dehydratase of S. cerevisiae is probably the first example of a eukaryotic D-serine dehydratase and that of a specifically zinc-dependent pyridoxal enzyme as well.