An amino acid residue functioning as a general base has been proposed to assist in the hydrolysis of beta-lactam antibiotics by the zinc-containing Bacillus cereus beta-lactamase II [Bicknell & Waley (1985) Biochemistry 24, 6876-6887]. Oligonucleotide-directed mutagenesis of cloned Bacillus cereus 5/B/6 beta-lactamase II was used in an ‘in vivo’ study to investigate the role of carboxy-group-containing amino acids near the active site of the enzyme. Substitution of asparagine for the wild-type aspartic acid residue at position 81 resulted in fully functional enzyme. An aspartic acid residue at position 90 is essential for beta-lactamase II to confer any detectable ampicillin and cephalosporin C resistance to Escherichia coli. Conversion of Asp90 into Asn90 or Glu90 lead to the synthesis of inactive enzyme, suggesting that the spatial position of the beta-carboxy group of Asp90 is critical for enzyme function.
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Research Article|
June 01 1991
Site-directed mutagenesis of dicarboxylic acids near the active site of Bacillus cereus 5/B/6 β-lactamase II
H M Lim;
H M Lim
1School of Life and Health Sciences, University of Delaware, Newark, DE 19716, U.S.A.
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R K Iyer;
R K Iyer
1School of Life and Health Sciences, University of Delaware, Newark, DE 19716, U.S.A.
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J J Pène
J J Pène
1School of Life and Health Sciences, University of Delaware, Newark, DE 19716, U.S.A.
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Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1991 The Biochemical Society, London
1991
Biochem J (1991) 276 (2): 401–404.
Citation
H M Lim, R K Iyer, J J Pène; Site-directed mutagenesis of dicarboxylic acids near the active site of Bacillus cereus 5/B/6 β-lactamase II. Biochem J 1 June 1991; 276 (2): 401–404. doi: https://doi.org/10.1042/bj2760401
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