TABLE 2.
Specific activities (in U/mg),a inhibitory concentrations of quinolones for supercoiling (IC50s in μM), and quinolone concentrations inducing cleavable complex (CC25s in μM) for the M. tuberculosis gyrases reconstituted with wt or modified GyrA and GyrB proteins
| Mutation(s) in:
|
Supercoiling sp act | IC50b
|
CC25
|
|||||
|---|---|---|---|---|---|---|---|---|
| GyrAc | GyrB | MXF | OFX | ENX | NAL | MXF | OFX | |
| wt | wt | 1 × 104 | 6 | 28 | 156 | 4,750 | 2 | 7 |
| A83S | wt | 4 × 104 | 2.5 | 7 | 16 | 950 | 0.5 | 1.5 |
| A83S S84A I85V | wt | 2 × 103 | 2.5 | 8 | 11 | 2,800 | 1 | 3 |
| α4 | wt | 2 × 103 | 2.5 | 7 | 16 | 1,080 | 1 | 3 |
| M74I | wt | 3 × 103 | 6 | 25 | >160 | 3,450 | 2.5 | ND |
| M74I A83S | wt | 9 × 103 | 1 | 3 | 9 | 850 | 0.5 | 1.5 |
| QRDR | wt | NO | NO | NO | NO | NO | 0.5 | 0.5 |
| wt | R447K | 5 × 103 | 1 | 7 | 23 | 1,080 | NO | NO |
| wt | N464S | 2 × 103 | 7 | 20 | ND | 4,100 | 3.5 | 14 |
| A83S | R447K | 5 × 103 | 2.5 | 4 | 19 | 850 | NO | NO |
| M74I A83S | R447K | 5 × 103 | 2 | 11 | 16 | 520 | NO | NO |
| GyrA of E. coli | GyrB of E. coli | 1 × 106 | 2.5 | 1.5 | 14 | 215 | 0.5 | 0.2 |
a
One unit is the amount of protein needed to produce 50% supercoiling of 0.4 μg of relaxed pBR322 DNA in 1 h at 37°C.
b
MXF, moxifloxacin; OFX, ofloxacin; ENX, enoxacin; NAL, nalidixic acid; NO, not observed; ND, not determined.
c
α4, substitutions A83S S84A I85V F96W P101M; QRDR, substitutions S69V A71G E72D T73V M74I N76K A83S S84A I85V W96F P101M.