Effects of a previously selected antibiotic resistance on mutations acquired during development of a second resistance in Escherichia coli

Table 2 Mutations associated with resistance to amoxicillin in strains with a previously acquired resistance to enrofloxacin, kanamycin, or tetracycline

Gene product	Gene	Mutation	Pop. frequency	Strains
Transcriptional regulator	acrR	L204R, Del C205	0.98–1	E_1/4, K_2/4 T_2/4
B-lactamase	*ampC*	C35A (promoter)	1	E_4/4, K_3/4, T_1/4
		C-11 T (promoter)	1	E_4/4, K_3/4, T_1/4
		Ins T after C4379837 (promoter)	1	K_1/4
		Ins T after A4379015 (promoter)	1	T_1/4
Citrate lyase	*citF*	G432A	1	E_4/4, K_3/4, T_1/4
Glutamate synthase subunit	gltD	A80A	0.18	T_1/4
L-glyceraldehyde 3-phosphate reductase	gpr	L180F	1	T_2/4
CPS-53 glucosyl transferase	gtrS	V351 V	0.96	K_1/4
Acetolactate synthase/acetohydroxybutanoate synthase subunit	ilvH	G52C	0.60–1	E_2/4, K_2/4, T_1/4
Branched chain amino acid/phenylalanine ABC transporter membrane subunit	livH	G239R	0.18	E_1/4
Intermembrane phospholipid transport system subunit	mlaF	Ins AIT between T38-A39	0.65–0.66	T_2/4
Large conductance mechanosensitive channel	mscL	L45Q	0.98	K_1/4
Mismatch repair protein	mutL	W390 L	0.11–0.2	T_2/4
Transcriptional regulator	*ompR*	E88A	1	E_4/4, K_3/4, T_1/4
RNA polymerase subunit α	rpoA	C269S	1	E_1/4, K_1/4
RNA polymerase subunit β	rpoB	E564A	0.15	T_1/4
Sigma 70	*rpoD*	D445V	1	E_4/4
Alternative sigma factor σS	rpoS	E16Stop	0.96–1	K_2/4, T_1/4
Alternative sigma factor σS	rpoS	Del Q59-E330	0.91–1	T_2/4
Potassium ion transporter	trkG	G159D	1	K_1/4

Del = deletion, Ins = insertion, underlined letters and numbers indicate nucleotides and their genomic position. Population frequency indicates the mutational frequency in the sequenced population. Strains indicates the prevalence of a mutation within different replicates. E: population with previously acquired resistance to enrofloxacin, K: population with previously acquired resistance to kanamycin, T: population with previously acquired resistance to tetracycline. X/Y: X indicates number of replicates with particular mutation, Y indicates total number of replicates that were sequenced. Mutations associated with resistance in a wild-type background are shown in bold. Mutations associated with the previous resistance have been omitted from the table

ISSN: 1471-2164