Table 3.

Plasmids used in this study.

Plasmid	Description	Host
pUC19	• High copy plasmid [41]; accession # L09137 • AmpR	• E. coli DH5α
pGP704	• Suicide vector [33] • Backbone from pBR322, ori R6K instead of ori E1 from pBR322, mob region from pRP4 • Replicates in E. coli SM10λpir but not in EHEC strains used because ori R6K needs π-Protein coded by the pir gene for replication • AmpR	• E. coli SM10λpir
pMHH1	• Derivative of pGP704 • Has a positive selection system based on the sacB gene from Bacillus subtilis [38]	• E. coli SM10λpir
pMHH6*	• Derivative of pUC19 • Harbors a 990 bp rpoS fragment from EHEC 86-24 amplified with primers RpoS 3/RpoS 4 and cloned via XbaI und SacI restriction sites	• E. coli DH5α
pMHH7*	• Derivative of pMHH6 • Restriction digest with DraIII und BsaAI leads to a 390 bp deletion in rpoS	• E. coli DH5α
pMHH8*	• Derivative of pMHH1 • Contains the mutagnized 600 bp rpoS fragment from pMHH7 cloned via XbaI and SacI restriction sites	• E. coli SM10λpir
pBR322	• Low copy plasmid [36]; accession # J01749 • AmpR, TetR	• E. coli DH5α • EHEC 126814
pSC1*	• Derivative of pBR322 • Harbors nlpD-rpoS from EHEC 126814 accession # DQ272417 amplified by PCR using primers RpoS 8/RpoS 9 and cloned via HindIII restriction sites	• E. coli DH5α • E. coli MHH126-5
pSC2*	• Derivative of pBR322 • Harbors nlpD-rpoS from EHEC EDL933a (rpoS*) accession # DQ272419 amplified by PCR with primers RpoS 8/RpoS 9 and cloned via HindIII restriction sites	• E. coli DH5α • E. coli MHH126-5
pMH33*	• Made from pSC2 by PCR mutagenesis using Primers RpoS 17a/RpoS 17b • Has point mutation rpoST721G which resolves the TAA stop codon at position 723 in $rpo{S}_{EDL933_a}$	• E. coli MHH126-5
pUD2*	• Derivative of pBR322 • Harbors nlpD-rpoS from EHEC EDL933b accession # DQ272421 amplified by PCR with primers RpoS 8/RpoS 9 and cloned via HindIII restriction sites	• E. coli MHH126-5
pUD4*	• Derivative of pBR322 • Harbors nlpD-rpoS from EHEC 86-24 accession # DQ272418 amplified by PCR with primers RpoS 8/RpoS 9 and cloned via HindIII restriction sites	• E. coli MHH126-5
pUD8*	• Derivative of pBR322 • Harbors nlpD-rpoS from STEC E-D53 accession # DQ272423 amplified by PCR with primers RpoS 8/RpoS 9 and cloned via HindIII restriction sites	• E. coli MHH126-5
pUD6*	• Derivative of pBR322 • Harbors nlpD-rpoS from STEC E-D68 accession # DQ272424 amplified by PCR with primers RpoS 8/RpoS 4c and cloned via HindIII restriction sites	• E. coli MHH126-5
pUD9*	• Derivative of pBR322 • Harbors nlpD-rpoS from STEC E-D68 accession # DQ272424 amplified by PCR with primers RpoS 8/RpoS 4c and cloned via HindIII restriction sites	• E. coli MHH126-5
pUD10*	• Derivative of pBR322 • Harbors nlpD-rpoS from EHEC 288597 accession # DQ272422 amplified by PCR with primers RpoS 8/RpoS 9 and cloned via HindIII restriction sites	• E. coli MHH126-5
pDS4*	• Derivative of pBR322 • Harbors nlpD-rpoS from EcN amplified by PCR with primers RpoS 8/RpoS 22 and cloned via HindIII restriction sites	• E. coli MHH126-5

All plasmids used in this study are listed with their names, descriptions and host strains. Sequenced rpoS genes were submitted to GenBank. Their accession numbers are given in the table. * = plasmid designed in this study