TABLE 1

Proposed properties of two DSBr pathways

FeaturesPairing pathwayDisjunction pathway
ProductsCrossovers and noncrossoversCrossovers only
Crossover InterferenceNo positive interferencePositive interference
Msh4–Msh5 dependenceNoneTotal
Bimolecular intermediateLong with junctions not fully ligatedShort with fully ligated Holliday junctions
Invasion heteroduplexPartly ephemeralEphemeral
MMR at invasion and annealingDependent on Msh2 and Mlh1None
MMR near the DSB siteDirected by 3′ invading and annealing endsMlh1 dependent; directed by junction resolution
Role of Msh2 in MMRRecognizes mismatches and attracts Mlh1None
Role of Msh4–Msh5 in MMRNoneAttracts Mlh1