Table 1 Bacterial strains and plasmids used in this work

Shigella flexneri

S. flexneri 2457T

Wild type strain

Laboratory stock

S. flexneri 2457T ΔgluQ-rs::kan

Deletion mutant of gluQ-rs gene

This work

Escherichia coli

E. coli W3110 ΔgluQ-rs::kan

Deletion mutant of gluQ-rs gene

[10]

DH5α

F ^- ϕ80lacZΔM15 Δ(lacZYA-argF) U169 recA1 endA1 hsdR17 (rK-, mK+) phoA supE44 λ-thi-1 gyrA relA1

[24]

BL21(DE3)

F ^- ompT gal dcm lon hsdS _B (r _B ^- m _B ^- ) λ(DE3 [lacI lacUV5-T7 gene 1 ind1 sam7 nin5])

Invitrogen

Plasmids

pTZ57R/T

bla, pMB1 ori, lacZ peptide, f1 phage ori

Fermentas®

pQF50

bla, pMB1 ori, lacZ gene without promoter

[23]

pET15c

Empty vector, a modified version of pET15b

This work

pVCDT

S. flexneri fragment from nucleotide +58^a of dksA gene to beginning of gluQ-rs gene (+590) cloned into pQF50. Pair of primers used were PgluQF/PdksARCT.

This work

pVCPDT

S. flexneri fragment from nucleotide −506 of dksA gene to beginning of gluQ-rs gene (+590) cloned into pQF50. Pair of primers used were PdksAF/PdksARCT.

This work

pVCPDTMut

S. flexneri fragment from nucleotide −506 of dksA gene to beginning of gluQ-rs gene (+590) cloned into pQF50, with the terminator mutated by the nucleotides indicated in Figure 4a.

This work

pVCPD

S. flexneri fragment from nucleotide −506 of dksA gene to nucleotide +527 (end of dksA gene) cloned into pQF50. Pair of primers used were PdksAF/PdksARST.

This work

pATGGQRS

S. flexneri gene from nucleotide +509 (stop codon of dksA) to nucleotide +1469 (last codon of gluQ-rs without stop codon). Pair of primers used were ATGGQRSF/ATGGQRSR.

This work