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Role of RecA in DNA replication. Yadi Zhou 2013.12.05. RecA protein. 38 kiloDalton Essential for the repair and maintenance of DNA A RecA structural and functional homolog has been found in every species Homologous protein in Homo sapiens is RAD51

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Role of RecA in DNA replication


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reca protein
RecA protein
  • 38 kiloDalton
  • Essential for the repair and maintenance of DNA
  • A RecA structural and functional homolog has been found in every species
  • Homologous protein in Homo sapiensis RAD51
  • Important enzyme in homologous recombination
  • Induce SOS response
reca filament
RecA filament

RecA-dsDNA

references
References
  • http://www.callutheran.edu/BioDev/omm/reca/recamast.htm
  • http://en.wikipedia.org/wiki/RecA
  • Nature Reviews Molecular Cell Biology 8, 127-138 (February 2007)
  • http://www.callutheran.edu/BioDev/omm/reca/recamast.htm
  • Nature 453, 463-466(22 May 2008)
mechanisms of reca dna repair

Mechanisms of RecA DNA Repair

Vivian Lesende

December 5, 2013

BIOS 7200

dna damage
DNA Damage
  • Can arrest replication --- deletions/genomic rearrangements, point mutations, lethality
  • Many types of lesions can inhibit normal progression of replication forks

-UV radiation – cis, syn-cyclobutane pyrimidine dimer (CPD) & pyrimidine-6-4-pyrimidone photoproduct (6-4 PP)

reca functions
RecA Functions
  • RecA functions to recover replication forks in several different ways

-acts as transactivator for upregulating over 40 genes (SOS response)

-protects single stranded DNA from degradation while replication is arrested

-promotes recombination repair

sos response1
SOS Response
  • LexA-- repressor binds to a 20 bp consensus sequence in operator region in DNA-damage inducible genes
  • RecA bound to damaged single stranded DNA causes autocatalytic cleavage
  • Increases transcription of genes involved in SOS Response
genes involved in sos response
Genes Involved in SOS Response
  • Genes that function to remove lesions and restore replication
  • uvrA&uvrB-- recognize UV-induced lesions
  • ydjQ(cho) -- incision step for excision repair
  • polB, dinB, umuC&umuD– DNA polymerases Pol II, PolI V, Pol V
sos response2
SOS Response

Courcelle & Hanawalt. Annu. Rev. Genet. 2003. 37:611-46

prevention of degradation of single stranded dna of replication forks
Prevention of Degradation of Single-Stranded DNA of Replication Forks
  • RecA maintains structure of replication forks until replication resumes
  • Allows for nucleotide excision repair to occur
  • recA mutants have high sensitivity to UV-light – “rec-less” degradation
prevention of degradation of single stranded dna of replication forks1
Prevention of Degradation of Single-Stranded DNA of Replication Forks

Courcelle & Hanawalt. Annu. Rev. Genet. 2003. 37:611-46

recombination recovery
Recombination Recovery
  • “postreplication repair” or “daughter-strand gap repair”
  • RecA promotes recombination as an alternative to excision repair – does not remove lesions from DNA
  • Typically only occurs if previous mechanisms have failed
recombination recovery1
Recombination Recovery

Courcelle & Hanawalt. Annu. Rev. Genet. 2003. 37:611-46

references1
References
  • J. Courcelle & P. C. Hanawalt. RecA-Dependent Recovery of Arrested DNA Replication Forks. Annu. Rev. Genet. 2003. 37:611-46