TABLE 1.
Bacterial strains and plasmids
| Strain or plasmid(s) | Characteristicsa | Reference(s) or source |
|---|---|---|
| Rhizobium sp. strains | ||
| NGR234 | Rifr derivative of wild-type Rhizobium sp. strain NGR234 isolated from Lablab purpureus (Rifr) | 39 |
| NGRΩexoF | NGR234 carrying an Ω insertion in the SstI site of exoF (Rifr Spr) | This study |
| NGRΩexoK | NGR234 carrying an Ω insertion in the BglI site of exoK (Rifr Spr) | This study |
| NGRΩexoL | NGR234 carrying an Ω insertion in the StyI site of exoL (Rifr Spr) | This study |
| NGRΩexoP | NGR234 carrying an Ω insertion in the C-terminal PstI site of exoP (Rifr Spr) | This study |
| NGRΩexoQ | NGR234 carrying an Ω insertion in the BstXI site of exoQ (Rifr Spr) | This study |
| NGRΩexoY | NGR234 carrying an Ω insertion between the two PstI sites of exoY (Rifr Spr) | This study |
| NGRΩexoZ | NGR234 carrying an Ω insertion in the BglII site of exoZ (Rifr Spr) | This study |
| E. coli DH5α | supE44 ΔlacU169 (φ80lacZΔM15) hsdR17 recA1 endA1 gyrA96 thi-1 relA1 | BRL, Bethesda, MD |
| Plasmids | ||
| pBluescript II KS(+) | High-copy-number ColE1-based phagemid (Apr) | Stratagene, La Jolla, CA |
| pExo1888 | pBluescript II KS(+) derivative carrying a 1.8-kb BamHI fragment of NGR234 containing exoZ (Apr) | This study |
| pExo8867 | pBluescript II KS(+) derivative carrying an 8.8-kb BamHI fragment of NGR234 containing exoP (Apr) | This study |
| pExo9987 | pBluescript II KS(+) derivative carrying a 9.9-kb BamHI fragment of NGR234 containing exoQ, exoF, exoY, exoK, and exoL (Apr) | This study |
| pHP45Ω | Vector containing an omega (Ω) interposon (Apr Spr) | 28 |
| pJQ200SK, pJQ200mp18, pJQ200uc1 | Suicide vectors used in directed mutagenesis (Ger) | 31 |
| pRK2013 | Tra+ helper plasmid for mobilization (Kmr) | 11 |
| pLAFR6 | Broad-host-range vector containing transcriptional terminators flanking cloning sites (Tcr) | D. Dahlbeck and B. Staskawicz, unpublished data |
| pFAJ1815 | Mini-Tn5 transposon derivative containing mTn5gfp-pgusA (constitutively expressed gusA) | 42 |
| pexoK | pLAFR6 derivative carrying a 2.9-kb BamHI-ApaI fragment of NGR234 containing exoK (Tcr) | This study |
| pEX41 | pSUP104 derivative carrying a 3.6-kb fragment of S. meliloti 1021 containing exoK (Tcr) | 21 |
| pEX80 | pSUP104 derivative carrying an 8-kb fragment of S. meliloti 1021 containing various exo genes but lacking exoK (Tcr) | 21 |
| pEX312 | pLAFR1 derivative carrying the exo gene cluster of S. meliloti 1021 (from exoP to exoB) (Tcr) | 21 |
| pD2 | pLAFR1 derivative carrying a fragment of S. meliloti 1021 containing exs genes (including exsH) (Tcr) | 19, 21 |
a
Apr, Ger, Kmr, Rifr, Spr, and Tcr, resistance to ampicillin, gentamicin, kanamycin, rifampin, spectinomycin, and tetracycline, respectively.