TABLE 1.

Bacterial strains, plasmids, and promoter fragments used in this work

Strain, plasmid, or promoter	Relevant characteristics	Reference or source
Strains
E. coli K-12 strains
JCB387	Δnir Δlac	21
JCB3884	JCB387 narL narP253::Tn10d(Cm)	25
JRG1728	Δfnr Δlac	26
Other strains
S. enterica serovar Typhimurium LT2	Wild type	I. Henderson
Plasmids
pAA121	Cloning vector for EcoRI-HindIII fragments derived from pBR322	14
pSR	pBR322 derivative containing a λ oop transcription terminator	15
pRW50	Broad-host-range lacZ fusion vector for cloning promoters on EcoRI-HindIII fragments; contains the RK2 origin of replication	18
Promoters
pnrf433	E. coli nrf promoter fragment carrying nucleotide sequences from positions −302 to +131	This work
pnrf53	E. coli nrf promoter fragment carrying nucleotide sequences from positions −209 to +131	25
pnrf53/Δ87	E. coli nrf promoter fragment carrying nucleotide sequences from positions −87 to +131	10
pnrf53/+5	E. coli nrf53 promoter fragment carrying 5-bp insertion at position −56	3
pnrf53/+10	E. coli nrf53 promoter fragment carrying 10-bp insertion at position −56	3
pnrf53/p54Gp51G	E. coli nrf53 promoter fragment carrying T-to-G and C-to-G substitutions at positions −54 and −51	3
pnrf53/STM	S. enterica serovar Typhimurium nrf promoter fragment carrying nucleotide sequences from positions −246 to +133	This work
pnrf53/Δ87 STM	S. enterica serovar Typhimurium nrf promoter fragment carrying nucleotide sequences from positions −87 to +133	This work
pnir7150	E. coli nir promoter fragment carrying nucleotide sequences from positions −150 to +36	25