TABLE 1.

Inhibitory activities of quinolones and novobiocin against topoisomerase IV

Compound	IC50 (μg/ml) for topoisomerase IV wild type or with indicated alteration(s)
	Wild typeab	GrlAa			GrlBc		GrlA (Phe-80) and GrlB (Asn-432)c
		Phe-80	Lys-84	Phe-80 and Lys-84	Asn-432	Asp-470
Levofloxacin	2.3	180	130	1,160	14.0 ± 1.3	3.4 ± 0.57	267 ± 17
Ofloxacin	3.9	260	285	1,250	41.6 ± 2.2	6.5 ± 2.45	784 ± 9.7
Sitafloxacin	0.45	4.2	13	170	2.5 ± 0.33	0.17 ± 0.02	11.6 ± 0.69
Ciprofloxacin	2.5	75	110	530	39.5 ± 6.3	4.0 ± 1.14	184 ± 32
Sparfloxacin	7.4	270	570	1,190	59.3 ± 2.8	8.9 ± 0.86	486 ± 40
Tosufloxacin	1.8	90	170	>200	8.2 ± 2.1	1.6 ± 0.01	71.8 ± 19.7
Novobiocin	16	14	10	11	16.4 ± 1.4	4.3 ± 1.86	24.8 ± 1.64

^aFrom reference 15. 

^bFor the wild type, GrlA contained Ser-80 and Glu-84 and GrlB contained Asp-432 and Asn-470. 

^cValues are expressed as means ± standard deviations.