Modification of a catalytically important residue of indoleglycerol‐phosphate synthase from Escherichia coli

FEBS Letters

Kirschner, Kasper¹  Eberhard, Marc¹ 

[1] Biozentrum der Universität, Abteilung Biophysikalische Chemie, Klingelbergstrasse 70, CH-4056 Basel, Switzerland

关键词: Indoleglycerol-phosphate synthase;    Catalytic mechanism;    Site-directed mutagenesis;    (Escherichia coli);    CdRP;    1-(2-carboxyphenylamino)-1-deoxyribulose 5-phosphate;    DTE;    1;    4-dithiothreitol;    IGP;    indoleglycerol phosphate;    PRA;    N-(5′-phosphoribosyl-1-)anthranilate;    PMSF;    phenylmethylsulfonyl fluoride;    rCdRP;    reduced CdRP;   

DOI  :  10.1016/0014-5793(89)80225-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The active-site residues of indoleglycerol-phosphate synthase from Escherichia coli were tentatively localized by comparing crystallographic data with the amino acid identities among the known indoleglycerol-phosphate synthase sequences. To test the validity of the resulting model of catalysis one of the residues in the presumptive active site, Lys 55, was changed to serine using oligonucleotide-directed mutagenesis. The specificity constant k _cat/K _m of the mutant is 3 × 10⁴-times lower than that of the wild-type enzyme, due to a 60-fold decrease in k _cat and a 450-fold increase in K _m. This finding shows that Lys 55 is important for both catalysis and substrate binding.

【 授权许可】

Unknown