Table 1

Recombinases and assembly factors

recssbMediatorMediator interactions*
ssbrecIndirect
T4UvsXgp32UvsY(62, 63)(62)
E. coli RecASSBRecO(39)
RecRRecO (39)
RecFRecR (64)
RecBCD
S. cerevisiae Rad51RPARad52(65)(66–68)
Rad55(67, 69)
Rad57Rad55 (52, 67, 69)
VertebratesRad51RPARad52(70)(71)
[Xrcc2]§Rad51D (72)
[Xrcc3](73)
[Rad51B]Rad51C (74)
[Rad51C](72)Xrcc3 (72)
[Rad51D]Rad51C (72)
[Brca1](75)Brca2 (76)
[Brca2](77, 81)
  • * Evidence for interaction includes biochemical (e.g.; affinity chromatography, immune precipitation, chemical cross-linking), and two-hybrid data. 

  • Although RecF has not been found to contribute to mediator activity directly, it can influence assembly of RecA and associates directly with RecR. 

  • RecBCD has been shown to promote assembly of RecA, although the mechanism may not involve displacement of SSB from ssDNA. Although there is no showing direct evidence for protein–protein interactions, the properties of certain RecB mutants strongly suggest that it is the subunit of RecBCD most closely involved in RecA assembly. 

  • § The proteins listed in parentheses have not been shown by biochemical experiments to be mediators. However, these protein are considered to be “putative mediators”, based on two properties: they bind directly or indirectly to recombinase via protein–protein interactions, and they are required for assembly of recombinase at sites of damage in vivo. (Xrcc3 is a likely orthologue of yeast Rad57, a known mediator protein.) We do not list proteins that influence recombinase assembly but are likely to act by posttranscriptional modification of recombinase. 

  • The interactions detected in this paper could have been direct or indirect protein–protein interactions with Rad51.