Mitsunobu, HitoshiZhu, BinLee, Seung-JooTabor, StanleyRichardson, Charles2014-09-082014Mitsunobu, Hitoshi, Bin Zhu, Seung-Joo Lee, Stanley Tabor, and Charles C Richardson. 2014. “Flap endonuclease of bacteriophage T7: Possible roles in RNA primer removal, recombination and host DNA breakdown.” Bacteriophage 4 (1): e28507. doi:10.4161/bact.28507. http://dx.doi.org/10.4161/bact.28507.2159-7073http://nrs.harvard.edu/urn-3:HUL.InstRepos:12785983Gene 6 protein of bacteriophage T7 has 5′-3′-exonuclease activity specific for duplex DNA. We have found that gene 6 protein also has flap endonuclease activity. The flap endonuclease activity is considerably weaker than the exonuclease activity. Unlike the human homolog of gene 6 protein, the flap endonuclease activity of gene 6 protein is dependent on the length of the 5′-flap. This dependency of activity on the length of the 5′-flap may result from the structured helical gateway region of gene 6 protein which differs from that of human flap endonuclease 1. The flap endonuclease activity provides a mechanism by which RNA-terminated Okazaki fragments, displaced by the lagging strand DNA polymerase, are processed. 3′-extensions generated during degradation of duplex DNA by the exonuclease activity of gene 6 protein are inhibitory to further degradation of the 5′-terminus by the exonuclease activity of gene 6 protein. The single-stranded DNA binding protein of T7 overcomes this inhibition.en-USflap endonucleasegene 6 proteinbacteriophage T7Okazaki fragmentDNA replicationJournal Article2014-09-0810.4161/bact.28507