Rewriting the rules for end joining via enzymatic splicing of DNA 3'-PO4 and 5'-OH ends.
There are many biological contexts in which DNA damage generates "dirty" breaks with 3'-PO4 (or cyclic-PO4) and 5'-OH ends that cannot be sealed by DNA ligases. Here we show that the Escherichia coli RNA ligase RtcB can splice these dirty DNA ends via a unique chemical mechanism. RtcB transfers GMP from a covalent RtcB-GMP intermediate to a DNA 3'-PO4 to form a "capped" 3' end structure, DNA3'pp5'G. When a suitable DNA 5'-OH end is available, RtcB catalyzes attack of the 5'-OH on DNA3'pp5'G to form a 3'-5' phosphodiester splice junction. Our findings unveil an enzymatic capacity for DNA 3' capping and the sealing of DNA breaks with 3'-PO4 and 5'-OH termini, with implications for DNA repair and DNA rearrangements.
Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065.
Ushati
U
Das
Anupam K
AK
Chakravarty
Barbara S
BS
Remus
Stewart
S
Shuman
D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D053960:DNA Breaks; D004260:DNA Repair / Q000502:physiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D000604:Amino Acyl-tRNA Synthetases; C561935:RtcB protein, E coli