Premium
Alternative Replisome Assembly is Directed by RecA to Bypass Obstacles
Author(s) -
ODonnell Mike Edward,
Georgescu Roxana,
Yao Nina Y.,
Langston Lance,
Isabel Kurth,
Indiani Chiara
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.218.2
Subject(s) - replisome , processivity , dna polymerase , biology , dna replication , polymerase , helicase , dna clamp , dna polymerase delta , dna polymerase ii , microbiology and biotechnology , genetics , dna repair , eukaryotic dna replication , dna , gene , rna , reverse transcriptase
Chromosomal replicases utilize circular sliding clamps for high‐processivity during replication. Sliding clamps not only bind the chromosomal replicase, but they also function with all 5 DNA polymerases in E. coli as well as other proteins for repair and lesion bypass. This presentation focuses on the use of the sliding clamp by a variety of DNA polymerases in crossing barriers that are encountered during replication. We find that the replicase, Pol III, acting in the context of a replisome including helicase, primase and the sliding clamp at a replication fork, can rapidly exchange with other DNA polymerases, such as translesion enzymes, that can allow the replisome to bypass lesions that it encounters during replication. We demonstrate that RecA, the recombinase, dictates the polymerase occupancy at the replication fork. To perform this function, RecA must be in the nucleofilament form, RecA*, which should only be present during DNA damage; it acts in trans . RecA* inhibits the Pol III chromosomal replicase, while greatly promoting translesion polymerases (TLS Pols), Pols II and IV. Interestingly, the polymerase that occupies the replisome dictates the speed of the helicase. We also find that RecA* converts TLS Pol V to a strand displacement enzyme, an activity needed for recombinational strand exchange. Finally, we present single‐molecule studies that examine the function of the third polymerase within the replisome.