TABLE 2.

Description of strains and plasmids used in the study

Strain or plasmid	Relevant details	Reference or source
Strains
E. coli MG1655	K strain, F− λ− rph-1	44
E. coli MG1655 ΔmutT::kan	MG1655 strain, where the mutT gene is disrupted with a kan cassette	28
E. coli BW25113	F− Δ(araD araB)567 ΔlacZ4787(::rrnB-3) λ− rph-1 Δ(rhaD rhaB)568 hsdR514	45
E. coli JW2502-1 Δndk::kan	BW25113 strain with Δndk-764::kan	45
E. coli CC101	F′ ara-600 Δ(gpt lac)5 λ− relA1 spoT1 thiE1 F128− (used to screen for A-to-C or T-to-G mutation)	42
E. coli CC101 ΔmutT::kan	CC101 strain with ΔmutT::kan allele	28
E. coli CC101 ΔmutT	A derivative of CC101 ΔmutT::kan strain in which the kanamycin marker cassette has been removed from the ΔmutT::kan locus to create an unmarked deletion of mutT	This study
E. coli CC101 ΔmutT Δndk	CC101 ΔmutT cured strain, in which the ndk allele has been disrupted by insertion of kan cassette	This study
Plasmids
pQE60	An E. coli expression vector harboring ColE1 origin of replication, ampicillin resistance marker, and T5 promoter (containing the lac operator) and provides a C-terminal His tag	Invitrogen
pQE60_Eco_ndk	pQE60 plasmid harboring Eco_ndk cloned (NcoI, BglII) under T5 promoter	This study
pBADHisB (pBAD)	An E. coli expression vector harboring ColE1 origin of replication, ampicillin resistance marker, and an arabinose-inducible promoter	Invitrogen
pBAD_Eco_mutT	Derivative of pBAD plasmid harboring Eco_mutT cloned (NcoI, NheI) under arabinose promoter	28
pBAD_Eco_ndk	A derivative of pBAD plasmid harboring Eco_ndk cloned (NcoI, BglII) under arabinose promoter	This study