A survey of a functional amino acid of class Cβ‐lactamase corresponding to Glu166 of class A β‐lactamases

FEBS Letters

Tsukamoto, Kikuo¹  Ishiguro, Masaji²  Sawai, Tetsuo¹  Tanimoto, Kyoko¹  Imajo, Seiichi²  Nukaga, Michiyoshi¹ 

[1] Division of Microbial Chemistry, Faculty of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Chiba 263, Japan;Laboratory of Molecular Design and Chemistry, Institute for Biomedical Research, Suntory Limited, 1-1-1 Wakayamadai, Shimamoto-cho, Mishima-gun, Osaka 618, Japan

关键词: β-Lactamase;    Citrobacter freundii;    Cephalosporinase;    Active site;    Glu166;    Site-directed mutagenesis;   

DOI  :  10.1016/0014-5793(93)80491-C

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The class C β-lactamase of Cltrobacter freundii GN346 is a typical cephalosporinase comprising 361 amino acids. The aspartic acid at position 217 and glutamic acid at position 219 in this β-lactamase were, respectively, previously shown not to be the counterpart of Glu¹⁶⁶ (ABL166) in class A β-lactamases, even though sequence alignment of class A and C enzymes strongly suggested this possibility [(1990) FEBS Lett. 264, 211-214; (1990) J. Bacteriol. 172, 4348-4351]. We tried again to assign candidates for the counterpart of Glu¹⁶⁶ through sequence alignment based on other criteria, the glutamic acids at positions 195 and 205 in the class C β-lactamase being selected. To investigate this possibility, these two glutamic acids were changed to glutamine, lysine or alanine, respectively. All the mutant enzymes showed more than 50% of the activity of the wild-type enzyme, indicating that the possibility was ruled out. These results strongly suggested the possibility that the class C β-lactamase lacks a functional acidic residue corresponding to Glu¹⁶⁶ in class A enzymes.

【 授权许可】

Unknown