TABLE 1.
E. coli K-12 strains and plasmids used in this work
| Strain or plasmid | Genotype | Source or reference |
|---|---|---|
| E. coli strain | ||
| TP71 | F−lysA opp araD139 rpsL150 relA1 deoC1 ptsF25 flbB5301 rbsR Δ(argF-lac) | 6 |
| TP73 | F− ΔampDE lysA opp araD139 rpsL150 relA1 deoC1 ptsF25 flbB5301 rbsR Δ(argF-lac) | 6 |
| TP73B | TP73 nagB::Kan | J. Park |
| TP75 | TP71 nagZ1 | This work |
| JM109 | F−traD36 lacIq Δ(lacZ)M15 proA+B+/e14− (McrA−) Δ(lac-proAB) thi gyrA96 (Nalr) endA1 hsdR17(rK− mK+) relA1 supE44 | New England Biolabs |
| BL21(DE3) | F−ompT [lon] hsdSB(rB− mB−; E. coli B strain) with DE3, a λ prophage carrying the T7 RNA polymerase gene | New England Biolabs |
| DY330 | W3110 Δ(lac)169 gal490* λ[cI857 Δ(cro-bio)] | D. Court |
| TP76 | DY330 nagZ::Cm | This work |
| TP77 | TP71 nagZ::Cm | P1(TP76) × TP71 |
| TP78 | TP73 nagZ::Cm | P1(TP76) × TP73 |
| TP78B | TP73B nagZ::Cm | P1(TP76) × TP73B |
| Plasmids | ||
| pGem-T | Cloning vector, Ampr | Promega |
| pKM1 | pGem-T carrying nagZ | This work |
| pKM3 | 178-bp NruI-ClaI fragment removed from pKM1, blunt ended, and replaced with a blunt 1,413-bp fragment containing the chloramphenicol acetyltransferase gene; Cmr | This work |
| pExoII | Plasmid expressing ExoII, Ampr | S. Roseman (2) |
| pEtslt70 | Plasmid expressing slt70, Ampr | A. Dijkstra |
| pACYC184 | Cloning vector, Cmr | New England Biolabs |