Table 5.

L4 mutant growth rates and macrolide sensitivity^a

L4 allele	Doubling time (min)	ERY doubling time (min)	ERY CDIC (μg/mL)	SPIR doubling time (min)	SPIR CDIC (μg/mL)
wild-type	31	151	200	149	750
Gln62Phe	47	63	1000	79	2500
Gln62Leu	44	63	1125	78	2500
Gln62Met	41	56	1125	60	1875
Gln62Asp	43	58	1000	75	2500
Gln62Glu	39	55	1000	78	1875
Gln62Lys	42	64	1125	66	1875
Gln62Arg	43	63	1125	75	2500
Lys63Glu	44	61	1250	68	1750
Lys63Asp	44	69	1000	104	1000
Lys63Leu	36	65	750	77	2000
Lys63Ala	34	58	500	90	1000
Lys63Val	34	59	500	92	875
Lys63His	37	59	1000	53	2000
Lys63Ile	46	68	1250	NDb	NDb
Lys63Gln	37	59	750	NDb	NDb
Gly66Cys	38	57	1250	56	2500
Gly66Ser	33	55	1000	55	1750
Gly66Ala	34	55	875	74	1250
Gly66Asp	32	56	875	69	1500
Gly66His	39	56	1000	54	1750
Gly66Arg	42	61	1250	56	2250

^aStrains were grown in LB media at 37 °C with aeration. Growth rates were determined in the presence of erythromycin (ERY) at 200 μg/mL and spiramycin (SPIR) at 750 μg/mL, and expressed as the time required for cell mass to double during logarithmic growth. Macrolide cell-doubling inhibitory concentrations (CDIC) were determined as described in Materials and Methods.

^bNot determined.