BIOL308 Lecture Notes - Lecture 11: Branch Migration, Holliday Junction, Rag1
4 Feb 2015
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Recall: in bacteria the major role of homologous recombination is to repair dsbs (which occur and can be repaired during replication) Chi ( ) sequences in e. coli: Overrepresented; > 1000 chi sequence in e. coli genome (would expect them to happen every 48 nucleotides; approximately 60-65 times) Recombination enhancers also exist in other organisms. 4: coli enzymes involved in homologous recombination, recbcd nuclease/helicase; binds to duplex. Dna and processes it into a substrate for recombination (generates single strands for invasion); requires atp: reca starts recombination by facilitating pairing of homologous dnas; involved in strand invasion, ruvab complex with helicase activity, recognizes. Holliday junctions, catalyses branch migration: ruvc endonuclease that catalyses the resolution of holliday junction. Recbcd destroys foreign dna (which lacks chi sequences) - protects cell. Homologous recombination in eukaryotes: between homologous chromosomes - crossing over. The hotspot distribution is positively correlated with gc content and distribution of repetitive sequences, and negatively correlated with the gene density.
