| Type: | Family | Name: | DNA helicase subunit AddB |
| Description: | DNA repair is accomplished by several different systems in prokaryotes. Recombinational repair of double-stranded DNA breaks involves the RecBCD pathway in some lineages, and AddAB (also called RexAB) in others. AddA is conserved between the firmicutes and the alphaproteobacteria, while its partner protein (RexB) is not. This entry describes the ATP-dependent nuclease subunit B (AddB/RexB) protein as found Bacillus subtilisand related species. Although the RexB protein of Streptococcus and Lactococcus is considered to be orthologous and functionally equivalent, merely named differently, all members of this protein family have a P-loop nucleotide binding motif GxxGxGK[ST] at the N terminus, unlike RexB proteins, and a CxxCxxxxxC motif at the C terminus, both of which may be relevant to function.The AddA/AddB heterodimer acts as both an ATP-dependent DNA helicase and an ATP-dependent, dual-direction single-stranded exonuclease. It recognises the chi site generating a DNA molecule suitable for the initiation of homologous recombination. The AddB nuclease domain is not required for chi fragment generation; this subunit has 5' ->3' nuclease activity. | Short Name: | DNA_helicase_suAddB |
