1. HPF1 dynamically controls the PARP1/2 balance between initiating and elongating ADP-ribose modifications.
- Author
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Langelier MF, Billur R, Sverzhinsky A, Black BE, and Pascal JM
- Subjects
- Blotting, Western, Carrier Proteins genetics, DNA genetics, DNA metabolism, DNA Breaks, Double-Stranded, Humans, Mutation, Nuclear Proteins genetics, Poly (ADP-Ribose) Polymerase-1 genetics, Poly(ADP-ribose) Polymerases genetics, Protein Binding, ADP-Ribosylation, Adenosine Diphosphate Ribose metabolism, Carrier Proteins metabolism, DNA Damage, Nuclear Proteins metabolism, Poly (ADP-Ribose) Polymerase-1 metabolism, Poly(ADP-ribose) Polymerases metabolism
- Abstract
PARP1 and PARP2 produce poly(ADP-ribose) in response to DNA breaks. HPF1 regulates PARP1/2 catalytic output, most notably permitting serine modification with ADP-ribose. However, PARP1 is substantially more abundant in cells than HPF1, challenging whether HPF1 can pervasively modulate PARP1. Here, we show biochemically that HPF1 efficiently regulates PARP1/2 catalytic output at sub-stoichiometric ratios matching their relative cellular abundances. HPF1 rapidly associates/dissociates from multiple PARP1 molecules, initiating serine modification before modification initiates on glutamate/aspartate, and accelerating initiation to be more comparable to elongation reactions forming poly(ADP-ribose). This "hit and run" mechanism ensures HPF1 contributions to PARP1/2 during initiation do not persist and interfere with PAR chain elongation. We provide structural insights into HPF1/PARP1 assembled on a DNA break, and assess HPF1 impact on PARP1 retention on DNA. Our data support the prevalence of serine-ADP-ribose modification in cells and the efficiency of serine-ADP-ribose modification required for an acute DNA damage response., (© 2021. The Author(s).)
- Published
- 2021
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