TABLE 2.
Effects of C•PvuII on restriction by the SptAI RM system
| Plating straina | Active PvuII gene(s)b | Apparent PFU/ml of lysate from strain carrying the plasmidc
|
|
|---|---|---|---|
| pBSH005 (none) | pMAN100 (SptAI) | ||
| pMAN100 + pACYC184 | None | 7.0 × 105 (1.0) | 3.6 × 107 (1.0) |
| pMAN100 + pRPS400 | C | 8.0 × 105 (1.1) | 2.1 × 107 (0.6) |
| pMAN100 + pPvuRM2.6CYC | C | 1.0 × 106 (1.4) | 2.2 × 107 (0.6) |
| pPvuRM3.4CYC | R, C, M | 4.2 × 103 (0.006) | 1.8 × 107 (0.5) |
One of two bacteriophage λ lysates was plated on each of these four strains. All strains are E. coli TOP10 (In Vitrogen) containing the indicated plasmid(s).
Abbreviations: C, regulatory gene pvuIIC; M, methyltransferase gene pvuIIM; and R, restriction endonuclease gene pvuIIR.
Numbers indicate apparent PFU per milliliter of lysate (normalized value in parentheses), calculated from plating a dilution series of two lysates. The lysates were prepared on host strains containing either no RM system or the SptAI system, as indicated in the column heading. The system (none or SptAI) is indicated at the top of each column. pMAN100 contains the entire SptAI RM system, pRPS400 and pPvuRM2.6CYC are both pACYC184-based plasmids that carry the intact pvuIIC gene and part of the pvuIIM gene, and pPvuRM3.4CYC is a pACYC184-based plasmid that carries the entire PvuII RM system (used as a positive control for restriction). pBSH005 carries the irrelevant E. coli gene yhhK.