cosB mutations that enable packaging by 21-specific terminases reduce packaging by λ-specific terminase

LineHelperaInitial cosbProphage yieldcd (SEM)HelperProphage initial cosProphage yieldcd (SEM)Discrimination indexe
1λ-P1 Nu1hy1 (Hλ Tλ H21 wλ)cosBλ0.20 (0.046)λ-P1 Nu1hy1 (Hλ Tλ H21 wλ)cosB212.87 (0.36)14.4
2λ-P1 Nu1+cos+Bλ0.84 (0.15)λ-P1 Nu1hy51 (H21 T21 H21 w21)cosBλ4.55 (0.12) × 10−51.8 × 104
3λ-P1 Nu1+cosBλC59G0.13 (0.016)λ-P1 Nu1hy51 (H21 T21 H21 w21)cosBλC59G2.05 (0.26) × 10−363
4λ-P1 Nu1+cosBλA117C0.09 (0.015)λ-P1 Nu1hy51 (H21 T21 H21 w21)cosBλA117C4.1 (1.7) × 10−4219
  • a The genetic background for helper phages was λ-P1:5R cI857 nin5 Δbet-gam∷kan. Helper phage yields varied from 0.58 to 3.03.

  • b The initial cos is the left cos at which DNA packaging initiates (Figure 2).

  • c Plaque-forming units/induced lysogen.

  • d Values in parentheses are the standard error of the mean (3 ≤ n ≤ 5).

  • e Discrimination index is the yield of cognate prophage/yield of noncognate passive prophage.