Shinohe T, Nojiri M, Saito T, Stanislawski T, Jendrossek D
Department of Biological Sciences, Kanagawa University, Japan.
FEMS Microbiol Lett. 1996 Jul 15;141(1):103-9. doi: 10.1111/j.1574-6968.1996.tb08370.x.
Mutational analysis of the poly(3-hydroxybutyrate) (PHB) depolymerase A of Pseudomonas lemoignei and of the poly(3-hydroxybutyrate) depolymerase of Alcaligenes faecalis revealed that S138 (P. lemoignei) and S139 (A. faecalis) are essential for activity. Both serines are part of a strictly conserved pentapeptide sequence which is present in all poly(3-hydroxybutyrate) depolymerases analyzed so far (G-L-S-S(A)-G) and which resembles the lipase box of lipases and other serine hydrolases (G-X-S-X-G). Mutation of another conserved serine, namely S195 (P. lemoignei) and S196 (A. faecalis), resulted in mutant proteins with almost full activity and proved that S195 and S196 are not essential for activity. The results indicate the structural and functional relationship of poly(3-hydroxybutyrate) depolymerases to the family of serine hydrolases.
对勒莫因氏假单胞菌的聚（3-羟基丁酸酯）（PHB）解聚酶A和粪产碱菌的聚（3-羟基丁酸酯）解聚酶进行突变分析发现，S138（勒莫因氏假单胞菌）和S139（粪产碱菌）对活性至关重要。这两个丝氨酸都是一个严格保守的五肽序列的一部分，该序列存在于迄今为止分析的所有聚（3-羟基丁酸酯）解聚酶中（G-L-S-S(A)-G），并且类似于脂肪酶和其他丝氨酸水解酶的脂肪酶框（G-X-S-X-G）。另一个保守丝氨酸即S195（勒莫因氏假单胞菌）和S196（粪产碱菌）的突变产生了具有几乎完全活性的突变蛋白，证明S195和S196对活性不是必需的。结果表明聚（3-羟基丁酸酯）解聚酶与丝氨酸水解酶家族之间的结构和功能关系。
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