Substitution of Asp-309 by Asn in the Arg-Asp-Pro (RDP) motif of Acetobacter diazotrophicus levansucrase affects sucrose hydrolysis, but not enzyme specificity

被引：52

作者：

Batista, FR ^{[1
]}

Hernández, L ^{[1
]}

Fernández, JR ^{[1
]}

Arrieta, J ^{[1
]}

Menéndez, C ^{[1
]}

Gómez, R ^{[1
]}

Támbara, Y ^{[1
]}

Pons, T ^{[1
]}

机构：

[1] Ctr Genet Engn & Biotechnol, Havana 10600, Cuba

来源：

BIOCHEMICAL JOURNAL | 1999年 / 337卷

关键词：

enzyme activity; beta-fructofuranosidase; fructosyl-transferase; LsdA; site-directed mutagenesis;

D O I：

10.1042/0264-6021:3370503

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

beta-Fructofuranosidases share a conserved aspartic acid-containing motif (Arg-Asp-Pro; RDP) which is absent from alpha-glucopyranosidases. The role of Asp-309 located in the RDP motif of levansucrase (EC 2.4.1.10) from Acetobacter diazotrophicus SRT4 was studied by site-directed mutagenesis. Substitution of Asp-309 by Asn did not affect enzyme secretion. The k(cat) of the mutant levansucrase was reduced 75-fold, but its K-m was similar to that of the wild-type enzyme, indicating that Asp-309 plays a major role in catalysis. The two levansucrases showed optimal activity at pH 5.0 and yielded similar product profiles. Thus the mutation D309N affected the efficiency of sucrose hydrolysis, but not the enzyme specificity. Since the RDP motif is present in a conserved position in fructosyltransferases, invertases, levanases, inulinases and sucrose-6-phosphate hydrolases, it is likely to have a common functional role in beta-fructofuranosidases.

引用

页码：503 / 506

页数：4

共 21 条

[1] Gapped BLAST and PSI-BLAST: a new generation of protein database search programs [J].