Chi site number and distribution in Enterobacteriales lambdoid phages are strongly correlated with absence of anti-RecBCD in diverse Rec modules
| Class | Prototype phagea | No. of phages | Anti-RecBCD | SSB | Nuclease | SAP | No. of Chi sites (top/bottom strand); range | No. with four or more top-strand Chi sites | No. with right-end clustered Chi sitesb |
|---|---|---|---|---|---|---|---|---|---|
| A (no Rec module)c | Larsen Lake Small (LLS) | 68 | – | – | – | – | 25/0–3/1 | 62 | 48 |
| B (no anti-RecBCD) | Gifsy-1 | 21 | – | – | + | + | 23/2–0/0 | 14 | 4 |
| Tritos | 4 | – | – | + | – | 21/6–7/2 | 4 | 3 | |
| Sum | 25 | 18 | 7 | ||||||
| C (anti-RecBCD) | λ | 102 | + | – | + | + | 15/1–0/0 | 8 | 0 |
| P22 | 46 | + | – | – | + | 13/4–0/0 | 4 | 0 | |
| HK75 | 27 | + | + | – | + | 11/0–0/0 | 11 | 2 | |
| ES18 | 25 | + | + | + | + | 5/0–0/0 | 1 | 0 | |
| Chronis | 2 | + | + | + | – | 0/0 | 0 | 0 | |
| Sum | 202 | 24 | 2 | ||||||
| D (other (diversity types) | mEp234 | 7 | – | + | – | + | 7/0–0/0 | 2 | 0 |
| Pocitis76 | 6 | – | + | + | + | 8/0–0/0 | 1 | 0 | |
| EhrS_49 | 3 | – | – | – | + | 7/0–0/0 | 1 | 0 | |
| SEN22 | 2 | – | + | + | – | 0/0 | 0 | 0 | |
| ZF40 | 1 | + | – | – | – | 19/2 | 1 | 0 | |
| Sum | 19 | 5 | 0 |
[i] aThe prototype phages of the 13 Rec module functional types illustrated by red brackets in Figure 5 and described in Supplemental Table S4.
[ii] bP < 0.1 for Kolmogorov–Smirnov test for clustering (Massey 1951); phages with fewer than four top-strand Chi sites were not considered to have significant right-end clustering regardless of P value.
[iii] cRecombination (Rec) modules are shown in Figure 5 and Supplemental Table S4.