Table 2 Bacterial strains and plasmids used in this study

E. coli

   N3431

rne-3071^ts, lacZ43, LAM-, relA1, spoT1 (CGSC#6975)

[36]

S. sonnei

   HW383

S. sonnei wild-type strain, (Tc^r)

[7]

   HW506

S. sonnei HW383 without pSS120 plasmid (Tc^r, non invasive)

[7]

   MS506

HW506 (Tc^s)

This study

   MS390

HW383 (Tc^s)

[13]

   MS1632

MS390ΔinvE

[11]

   MS2830

MS390ΔcpxR (cpxR: chromosomal activator of virF gene)

[13]

   MS4831

MS390Δhfq

[11]

   MS4841

MS390Δhns (non invasive)

[11]

   MS5400

MS390Δrne _701–892 ::aphA

This study

   MS5512

MS390ΔpinvE::paraBAD

[11]

S. flexneri

   2457T

S. flexneri 2a wild-type strain,

[49]

   2457O

2457T carrying mutation in virF gene (non-invasive)

[50]

   MF4835

2457TΔhfq::aphA

[11]

Plasmids

   pBAD-invE

PCR-amplified invE gene was cloned into pBAD24 (Ap^r)

[11]

   pHW848

virF-lacZ translational fusion plasmid (Cm^r)

[8]

   pJK1142

invE and ipa-mxi-spa (TTSS) genes encoding plasmid (Km^r)

[4]

   pJK1143

virF-encoding plasmid (Cm^r)

[4]

   pJM4320

invE-lacZYA transcriptional fusion in pTH18cs5(Cm^r)

[13]

   pJM4321

invE-lacZYA translational fusion in pTH18cs5(Cm^r)

[13]

   pTrc99A

IPTG inducible expression plasmid(Ap^r)

[51]

   pTrc-hfq

PCR-amplified hfq gene was cloned into pTrc99A(Ap^r)

[11]