Phosphate steering by Flap Endonuclease 1 promotes 5'-flap specificity and incision to prevent genome instability.

ABSTRACT: DNA replication and repair enzyme Flap Endonuclease 1 (FEN1) is vital for genome integrity, and FEN1 mutations arise in multiple cancers. FEN1 precisely cleaves single-stranded (ss) 5'-flaps one nucleotide into duplex (ds) DNA. Yet, how FEN1 selects for but does not incise the ss 5'-flap was enigmatic. Here we combine crystallographic, biochemical and genetic analyses to show that two dsDNA binding sites set the 5'polarity and to reveal unexpected control of the DNA phosphodiester backbone by electrostatic interactions. Via 'phosphate steering', basic residues energetically steer an inverted ss 5'-flap through a gateway over FEN1's active site and shift dsDNA for catalysis. Mutations of these residues cause an 18,000-fold reduction in catalytic rate in vitro and large-scale trinucleotide (

SUBMITTER: Tsutakawa SE 

PROVIDER: S-EPMC5490271 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature