TABLE 3.

Results for mutation frequencies, complementation studies, and sequencing of MMR system genes in the CF mutator isolates

IsolateFrequency of mutation to rifampin (300 μg/ml) resistanceComplementationaSequencing of MMR system genesb
mutS (pUCPMS)mutL (pUCPML)
PAO12.4 × 10−8 ± 1.3 × 10−8
PAOMSc4.0 × 10−6 ± 1.2 × 10−6+
PAOMAc1.1 × 10−8 ± 0.2 × 10−8
PAOMSAc3.1 × 10−6 ± 1.0 × 10−6+
2-12.8d4.1 × 10−6+mutL, 2-bp insertion (CG) after nucleotide 1822
2-133.6 × 10−6+mutL, 2-bp insertion (CG) after nucleotide 1822
8-1.12.7 × 10−7MutS, wild type; MutL, G427S
8-13.2A7.6 × 10−7NDNDmutS, 4-bp deletion (CGAG) at nucleotide 1761; MutL, G427S
13-19.6A1.1 × 10−6+MutS, A187S; mutS, 4-bp insertion (CGCC) after nucleotide 1600
13-19.6B3.7 × 10−7+MutS, A187S; mutS, 4-bp insertion (CGCC) after nucleotide 1600
17-22.22.3 × 10−7mutS, wild type; mutL, wild type
21-14.32.2 × 10−6+mutS, 1-bp deletion (T) at nucleotide 2437; mutL, wild type
21-15.24.1 × 10−6+mutS, 1-bp deletion (T) at nucleotide 2437; mutL, wild type
21-19.53.9 × 10−6+mutS, wild type; MutL, T118A, A124V
22-204.4 × 10−6+MutS, A187S, R306C
23-6.24.6 × 10−6+MutL, Q492X
25-214.9 × 10−6+mutS, 1-bp deletion (A) at nucleotide 2428
30-16.81.2 × 10−6+mutL, 1-bp insertion (C) after nucleotide 100
30-18.53.4 × 10−6+mutL, 1-bp insertion (C) after nucleotide 100
  • a Complementation was considered positive when the mutation frequency after transformation of pUCPMS or pUCPML was decreased ≥2 logs, negative when the mutation frequency was decreased <1 log, and partial if the reduction was 1 log. In one case it was not possible to perform complementation (ND) due to the high level of gentamicin resistance of the clinical strain.

  • b Inactivating mutations are indicated by bold type.

  • c PAOMA is a mucA mutant of PAO1, PAOMS is a mutS mutant of PAO1, and PAOMSA is a mutS mucA mutant of PAO1.

  • d Patient number-age (in years) at the time of isolation.