TABLE 1.

Bacterial strains and plasmids used in this study

Strain or plasmidRelevant characteristicsSource or reference
Escherichia coli strains
    DH5αFsupE44 ΔlacU169(φ80dlacZΔM15) hsdR17(rK mK+) recA1 endA1 gyrA96 thi-I relA1Bethesda Research Laboratories
    MT616MT607(pRK600)8
    BL21(DE3)(pLysS)F ompT hasdSB (rB mB) gal dcm (DE3) pLysS (Cmr)Novagen
Sinorhizobium meliloti strains
    RCR2011SU47, wild type30
    1021Derivative of RCR2011, Strr20
    GM1211Derivative of RCR2011, Strr Lac23
    5000Derivative or RCR2011, Rifr8
    M1ARm5000 choX::Ω, Rifr SprThis study
Plasmids
    PLAFR3IncP cosmid cloning vector, Tcr10
    pRK600ColE1 replicon with RK2 transfer region, Cmr8
    pBluescriptSK(−)Derivative of pUC19 with f1(−)oriR, AmprStratagene
    pGEM T-3Zf(+)Cloning vectorPromega
    pET20-b(+)Derivative of pBR322, T7 promoter, 3′ His codons, AmprNovagen
    pSUP202ColE1, Mob+ Tcr Ampr Cmr33
    pHP45-ΩApr, pBR322 derivative with interposon Ω Smr/Spr28
    pGQ5pGEMT vector with bup1-pro4-amplified fragmentThis study
    pF1pLAFR3 with an S. meliloti 16-kb insert containing cho locusThis study
    p1.2E1.2-kb EcoRI fragment from pF1 cloned into pBSSK vectorThis study
    p1.5E1.5-kb EcoRI fragment from pF1 cloned into pBSSK vectorThis study
    p3.4HE3.4-kb HindIII-EcoRI fragment from pF1 cloned into pBSSK vectorThis study
    p6.5H6.5-kb HindIII fragment from pF1 cloned into pBSSK vectorThis study
    pSUP6.5H6.5-kb HindIII fragment from pF1 cloned into pSUP202 vectorThis study
    pXΩpSUP6.5H, choX::Ω (BglII insertion)This study
    pETNEpET20b, Nde1-EcoRI fragment (choX without His codon fusion)This study
    pETNXpET20b, Nde1-Xho1 fragment (choX with 3′ His codon fusion)This study