TABLE 7.
Position(s) within TR | Change(s) in indicated Qnr causing a decrease in protection |
|||
---|---|---|---|---|
QnrA1 | QnrB1 | QnrC1 | QnrS1 | |
Loop A | ΔA41–G56 | |||
ΔI49–E55 | ||||
ΔS51–G56 | ||||
Y46A | ||||
ΔY46–Q51 | ||||
S50A | ||||
ΔG56/D | ΔG53A/D/E | ΔG56D/E | ||
Loop B | N103A | |||
M104A | ||||
ΔM104–S113 | ||||
I105A | V108A | |||
ΔT106 | S109A | |||
ΔT106–T107 | ||||
ΔT107 | ||||
ΔR108 | ||||
ΔT106–R108 | ||||
ΔT107-R108 | ||||
M112A | ||||
W110A | Y113A | |||
F114D | F111A/D | F114A | ||
C115Y | C112A/Y | C115A/Y | ||
R58H + R87H + C112Yb + N178Y | ||||
S116D | S113A/D | S116P | S116A | |
Loops A + B | ΔY46–Q51 + ΔM104–S113 |
Amino acid substitutions are listed from top to bottom in the direction from the N to C termini. Changes in the same row are analogous to each other. The amino acids highlighted in boldface type are those leading to a full loss of Qnr activity and a subsequent lack of an effect on the final quinolone MICs. Note that cloning in different vectors may slightly affect the final full or partial loss of activity. The amino acid change is reported only when there is a positive or negative effect of at least 4-fold on the MIC of the quinolones described. Note that different studies have determined the Qnr effect on different quinolones. Loop A, amino acids 46 to 53 (QnrB) and amino acids 49 to 56 (QnrA, QnrC, QnrS, and QnrVC); loop B, amino acids 102 to 113 (QnrB); TR, tandem repeat; Δ, deletion (based on data from references 234, 235, 376, and 391–394).
The amino acid change C112Y is located in loop B.