TABLE 1.
Strains and plasmidsa
| Strain or plasmid | Relevant genotype | Reference or source |
|---|---|---|
| Salmonella enterica | ||
| TR6583, formerly SA2929 | metE205 ara-9 | K. Sanderson via J. Roth |
| Derivatives of TR6583 | ||
| JE2192 | cobT109::MudI1734b (lacZ+kan+) cobC1175::Tn10d16d17 (tet+) | Laboratory collection |
| JE7493 | JE2192/pCOBZ2 | |
| JE7404 | JE2192/pJO46 | |
| JE7403 | JE2192/pT7-7 | |
| JE7492 | JE2192/pT7-5 | |
| Escherichia coli | ||
| BL21 λDE3 | PlacUV5-T7 RNA polymerase | Novagen |
| Plasmids | ||
| pCOBZ1 | M. mazei Gö1 cobZ+ in pET-16b | |
| pCOBZ2 | M. mazei Gö1 cobZ+ in pT7-7 bla+ | |
| pJO46 | cobC+ in pT7-5 bla+ | 15 |
| pT7-5, pT7-7 | Cloning vectors bla+ | 23 |
| pET-16b | Cloning vector bla+ | Novagen |
| Halobacterium sp. strains | ||
| JE6693 | Δura-3 ΔVng1577-1 | |
| JE6792 | Δura-3 ΔVng1577-1 ΔcbiP1 |
All S. enterica strains used in these studies carry a null allele of the metE gene (16), making growth of the cell dependent on the activity of the Cbl-dependent methionine synthase (MetH) enzyme (9, 10, 24). No-carbon E (NCE) medium (2) was used as minimal medium. When added, the following supplements were at the indicated concentrations: glucose, 11 mM; MgSO4, 1 mM; corrinoids (cobyric acid, cobinamide, cobalamin), 10 nM; 5,6-dimethylbenzimidazole (DMB), 0.3 mM; and trace minerals, 10 ml/liter (1). All cobyric acid (Cby), Cbi, and Cbl (Sigma) were added in their cyano forms; DMB was purchased from Aldrich. Nutrient broth (NB; Difco Laboratories) (0.8%, wt/vol) containing NaCl (85 mM) was used as rich medium to culture S. enterica strains; lysogeny broth (LB) (3, 4) was used as rich medium to culture E. coli strains. Strains and plasmids were constructed during the course of this work unless stated otherwise.
The MudI1734 element is described elsewhere (8).