Table 3. Effects of genetic modification the C-terminal needle domain.
Phage sourcea | Lysate titerb | Virion infectivityc |
UB-1790 Parent P22 phaged | 1.7×1010 | 1.0 |
UB-2083 HS1-1 hybrid needle phage | 7.5×109 | 1.1 |
UB-1918 Sf6-3 hybrid needle phage | 6.2×109 | 2.1 |
UB-1919 Glu146Asp | 5.5×109 | 0.8 |
UB-1920 Glu146Ala | 5.2×109 | 1.7 |
UB-1925 Lys200Ala | 1.4×109 | 2.0 |
UB-1926 Lys200Glu | 2.6×109 | 1.4 |
UB-1921 Ser248Thr | 6.3×109 | 2.0 |
UB-1922 Ser248Ala | 3.8×109 | 2.1 |
UB-1924 Asp250Ala | 2.1×109 | 2.9 |
UB-1927 Glu146Ala/Asp250Ala | 1.8×1010 | 1.0 |
UB-1928 Lys200Ala/Asp250Ala | 1.4×109 | 1.8 |
UB-1929 Glu146Ala/Lys200Ala | 2.9×109 | 1.3 |
UB-1941 Foldon | 8.3×109 | 0.13 |
Salmonella lysogens are listed that were induced to prepare stocks of the phages in the table; the amino acid changes in the L-glutamate binding site of the needle are shown after the Sf6-hybrid needle phage strain names (UB-1919 to 1929).
Lysogens were induced with mitomycin C and titered on Salmonella strain UB-0002; average results from several replicates are shown.
Phage particles were purified through CsCl step gradients [68], and phage titers were determined on Salmonella strain UB-0002. Relative PFU/particle ratios were calculated by normalization to UB-1790 titer (PFU) and to the intensity of quantified coat protein bands in SDS electrophoresis gels and/or OD280 (particles). Several replicates were performed for each phage with similar results, and the average value is shown.
The prophages all have the following genetic background: P22 26::Sf6-3, sieA–Δ1, 15–ΔSC302::KanR, 13–amH101 (see table 2).