Table 5.
Summary of recBCD phenotypes
| Enzyme | DNA damage*
|
Recombination†
|
Enzyme activity‡
|
||||||
|---|---|---|---|---|---|---|---|---|---|
| UV | Mit. C | Hfr | λ×λ | Chi | Exo | Unwinding | Chi | RecA loading | |
| RecBCD | R | R | + | + | + | + | + | + | +¶ |
| RecBC | R | R | + | + | − | − | +§ | − | +‖ |
| RecBD1080ACD | S | S | − | − | − | − | + | − | − |
| RecBD1080AC | R | R | + | + | − | − | +§ | − | +‖ |
*
S, sensitive to agent; R, resistant to agent.
†
Recombination proficiency and Chi activity in Hfr and lambda red− gam− crosses. +, recombination-proficient or Chi active; −, recombination-deficient or Chi inactive.
‡
Activity in enzyme assays. +, activity present; −, activity absent.
§
Unwinding by RecBC or RecBD1080AC enzyme requires higher protein concentrations because of their lower affinity for DNA than RecBCD or RecBD1080ACD enzyme (>200-fold for RecBC enzyme compared to RecBCD enzyme, unpublished observations).
¶
RecA loaded on 3′ Chi tail.
‖
RecA loaded constitutively on 3′ end.