Function of the conserved triad residues in the class C β‐lactamase from Citrobacter freundii GN346

FEBS Letters

Tsukamoto, Kikuo¹  Sawai, Tetsuo¹  Tsuruoka, Miyuki¹  Nishida, Naoko¹ 

[1] Division of Microbial Chemistry, Faculty of Pharmaceutical Sciences, Chiba University, Chiba 260, Japan

关键词: β-Lactamase;    Cephalosporinase;    Active site;    Conserved residue;    Site-directed mutagenesis;    Citrobacter freundii;   

DOI  :  10.1016/0014-5793(90)80416-G

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The conserved KTG triad in the class C β-lactamase from Citrobacter freundii GN346 was examined as to its function by means of site-directed mutagenesis. The following conversions were performed; Lys-315 to arginine, alanine or glutamic acid, Thr-316 to valine, and Gly-317 to alanine, proline or isoleucine. The resultant mutant enzymes revealed that a basic amino acid at position 315 and a small uncharged residue at position 317 are essential for the enzyme activity, but a hydroxyl group at residue 316 is not required for the enzymatic catalysis. The kinetic properties of the purified Arg-315 and Val-316 enzymes provided information on the function of these residues.

【 授权许可】

Unknown