Table 1.

Types of mutant β-lactamases selected by growth of transformants in the presence of ampicillin plus clavulanate

Mutant typeaAmino acidb substitutions for the following amino acids of the wild-type TEM-1 β-lactamase:Silent mutation(s)c
A42N52M69dK111S130H153K192T195L201G238R244T272N276
1N52Y M69L T272AA42A, T281T
2 M69L K192RR9R, Q206Q
3 S130G
4A42G S130G T195AG238ST265T
5 R244C
6A42GL201P R244C L73L
7A42GH153D R244C R9R, K34K, L49L, R61R, Q88Q, K111K
8A42GK111RL201P R244C R9R, K34K, L49L, R61R, G87G, I260I
9 R244S G45G, P257P
10L201P R244S R65R, P67P, I260I
11 N276D
  • a The wild type is TEM-1.

  • b Amino acids are indicated by conventional single-letter nomenclature.

  • c Mutations in the base sequence of the gene that do not alter the amino acid sequence of the enzyme.

  • d The boldface font indicates sites at which mutations have previously been reported to confer resistance to β-lactam–clavulanate combinations.