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Table 1 Ciprofloxacin susceptibility of QnrC and QnrA1 mutants.

From: A mutational analysis and molecular dynamics simulation of quinolone resistance proteins QnrA1 and QnrC from Proteus mirabilis

Groups/clusters

Mutagenesis and codon alteration a

Position of mutation

Qnr protein

MIC (μg ml-1)

 

pHSG398

-

-

0.002

Control

pHS12

wild type

QnrC

0.125

 

pMG252-1

wild type

QnrA1

0.125

 

L38R(TTA→AGA)

i

QnrC

0.003

 

L38A(TTA→GCA)

i

QnrC

0.125

Hydrophobic interior of β-helix

L38F(CTG→TTC)

i

QnrA1

0.125

 

F13S(TTC→TCC)c

i

QnrA1

0.008

 

C72Y(TGC→TAC) or A97Y(GCT→TAT)

i-2

QnrC

0.003

 

S116P (TCT→CCT) c

i+2

QnrC

0.002

Constraint effect of Pro to the backbone

S153P(TCT→CCT)c

i-1

QnrC

0.003

 

L38P(CTG→CCG)c

i

QnrA1

0.004

 

C84S(TGT→TCT)

i

QnrC

0.094

 

C84S(TGC→AGC)

i

QnrA1

0.064

Cys to Ser mutation

C31 S or C36 S or C57 S or C177 S (TGT→AGT);

C26 S or C46 S or C72 S or C92 S or C122 S or C137S(TGC→AGC)

i-2

QnrA1

0.125

 

C133S(TGC→AGC)or C168S(TGT→AGT)

i-1

QnrA1

0.125

 

C115S(TGC→AGC)or C200S(TGT→AGT)

i+1

QnrA1

0.125

 

Δ11-20

N-terminus

QnrC

0.003

 

Δ2-21

N-terminus

QnrA1

0.002

 

Δ2-10

N-terminus

QnrA1

0.003

 

Δ49-55

G56 region

QnrC

0.003

Fragment truncation b

Δ41-56, Δ51-56

G56 region

QnrA1

0.003

 

Δ77-96, Δ137-156

β-helix backbone

QnrC

0.003

 

Δ216-218

C-terminus

QnrC

0.064

 

Δ187-218

C-terminus

QnrA1

0.003

 

Δ207-218

C-terminus

QnrA1

0.004

 

D188V (GAC→GTC)c

i+1

QnrA1

0.003

Others

M44T(ATG→ACG)

i+1

QnrC

0.125

 

I216T (ATT→ACT) c

i+2

QnrC

0.125

 

E50A(GAA→GCC) or E50G (GAA→GGC) or E55A (GAA→GCT) or E55G(GAA→GGA)

i+2

QnrA1

0.125

  1. a nucleotide substitution is in parentheses
  2. b Δ2-21 indicates deletion of amino acids 2-21
  3. c mutations were obtained by random mutagenesis and confirmed by site-directed mutagenesis