Several labels were missing from Figure 2 in the published version of this article: the correct version appears here.

Homology-directed repair in eukaryotic cells

Figure 2
Homology-directed repair in eukaryotic cells

(A) Induction of a DSB is recognized by the MRN complex, which tethers the DNA ends together and participates in end processing. The CtIP–BRCA1–BARD1 complex co-operates with the MRN complex to aid in end resection. ssDNA is initially bound by the ssDNA-binding protein RPA to keep the ssDNA from forming secondary structures. BRCA1/BARD1 promotes accumulation of BRCA2 via PALB2. (B) BRCA2 catalyses the nucleation of Rad51 on to the free 5′ end of a dsDNA–ssDNA junction. Once the Rad51 filament is assembled it captures duplex DNA and searches for homology. (C) The SDSA model predicts that a migrating D loop fails to capture the second DNA end and, following extension, the invading strand is displaced and anneals with the resected second end. (D) The DSB repair model predicts that the second DNA end is captured by annealing to the extended D loop, forming two HJs. (E) The double HJ structure is then resolved to yield either crossover or non-crossover products. (F) The SSA pathway: a break near one of two direct repeat sequences leads to annealing of complementary strands from each repeated sequence. The product of this repair event contains a single copy of the repeat with a deletion of the intervening sequences. (G) BIR occurs when the 3′ end of the invading strand leads to the formation of a replication fork, potentially copying long tracts from the donor DNA molecule. Dotted arrows indicate new DNA synthesis.

Figure 2
Homology-directed repair in eukaryotic cells

(A) Induction of a DSB is recognized by the MRN complex, which tethers the DNA ends together and participates in end processing. The CtIP–BRCA1–BARD1 complex co-operates with the MRN complex to aid in end resection. ssDNA is initially bound by the ssDNA-binding protein RPA to keep the ssDNA from forming secondary structures. BRCA1/BARD1 promotes accumulation of BRCA2 via PALB2. (B) BRCA2 catalyses the nucleation of Rad51 on to the free 5′ end of a dsDNA–ssDNA junction. Once the Rad51 filament is assembled it captures duplex DNA and searches for homology. (C) The SDSA model predicts that a migrating D loop fails to capture the second DNA end and, following extension, the invading strand is displaced and anneals with the resected second end. (D) The DSB repair model predicts that the second DNA end is captured by annealing to the extended D loop, forming two HJs. (E) The double HJ structure is then resolved to yield either crossover or non-crossover products. (F) The SSA pathway: a break near one of two direct repeat sequences leads to annealing of complementary strands from each repeated sequence. The product of this repair event contains a single copy of the repeat with a deletion of the intervening sequences. (G) BIR occurs when the 3′ end of the invading strand leads to the formation of a replication fork, potentially copying long tracts from the donor DNA molecule. Dotted arrows indicate new DNA synthesis.