Post on 04-Jan-2016
MCB 7200
Group 1Ashley PattonYanyang CuoSamantha Shaw
Biological Relevance◦ Repairs double-stranded breaks◦ Chromosome segregation during meiosis I◦ Genetic diversity in gametes
Mediated by two important enzymes◦ Rad51 and Dmc1
Occurs during late-S phase, G2, M
Filippo et al. 2008. Mechanism of Eukaryotic Homologous Recombination
Double Strand Break Repair
Synthesis-dependent strand annealing ◦ Migrating D loop◦ No Holiday Junction formation◦ Mitosis/Meiosis
Single strand annealing◦ Repair of double strand break by deletion of repeated DNA
sequences ◦ No Holiday Junction formation
Break-induced repair◦ Telomeres ◦ Replication forks
Filippo et al. 2008. Mechanism of Eukaryotic Homologous Recombination
RecBCD◦ Helicase activity unwinds
DNA◦ Exonuclease activity
degrades both single strands◦ At CHI site
3′ - 5′ Exonuclease activity is inhibited
5′ -3′ activity enhanced yielding a single-stranded 3′ end. This end becomes coated
with multiple RecA proteins, which catalyze strand invasion and formation of a Holliday structure
Lodish et al., Molecular Cell Biology, 4 th Fig 12-32
RecA◦ RecA binds ssDNA in the presence of ATP◦ RecA aligns the ssDNA with its
homologous dsDNA region◦ RecA inserts the ssDNA into target DNA
sequence forming a heteroduplex Holiday-type structure
Branch Migration and Resolution by RuvA,B,C
Lodish et al., Molecular Cell Biology, 4 th Fig 12-35
http://www.qiagen.com/products/genes%20and%20pathways/pathway%20details.aspx?pwid=143
http://www.qiagen.com/products/genes%20and%20pathways/pathway%20details.aspx?pwid=143
Filippo et al. 2008. Mechanism of Eukaryotic Homologous Recombination
Used for double strand break repair and genetic diversity in meiosis.
Different mechanisms within the Eukaryotic and Prokaryotic cells.
Proteins are different with each system by have similar functions.
C. Wyman et al. /DNA Repair 3 (2004) 827–833
Fillipo et al. Mechanism of Eukaryotic Homologous Recombination. 2008. Annual Rev. Biochem. 77:229-57.
Lodish et al. Molecular Cell Biology. 1999. W. H. Freeman. 4th edition. Oldenburg et al. Recombination-mediated PCR directed plasmid construction in
vivo in yeast. 1997. Nucleic Acids Research. Vol. 25, No. 2. Wyman et al. Homologous recombination-mediated double-strand break repair.
(2004) DNA Repair. 3:827–833.