HPF1 and nucleosomes mediate a dramatic switch in activity of PARP1 from polymerase to hydrolase

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Abstract

Poly(ADP-ribose) polymerase 1 (PARP1) is an important player in the response to DNA damage. Recently, histone PARylation factor (HPF1) was shown to be a critical modulator of the activity of PARP1 by facilitating PARylation of histones and redirecting the target amino acid specificity from acidic to serine residues. Here we investigate the mechanism and specific consequences of HPF1-mediated PARylation using nucleosomes as both activators and substrates for PARP1. HPF1 provides that catalytic base Glu284 to substantially redirect PARylation by PARP1 such that the histones in nucleosomes become the primary recipients of PAR chains. Surprisingly, HPF1 partitions most of the reaction product to free ADPR, resulting in much shorter PAR chains compared to reactions in the absence of HPF1. This HPF1-mediated switch from polymerase to hydrolase has important implications for the PARP1-mediated response to DNA damage and raises interesting new questions about the role of intracellular ADPR and depletion of NAD⁺.

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All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for all Figures.

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Johannes Rudolph

Department of Chemistry and Biochemistry, University of Colorado, Boulder, Boulder, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-0230-3323
Genevieve Roberts

Department of Chemistry and Biochemistry, University of Colorado, Boulder, Boulder, United States

Competing interests
The authors declare that no competing interests exist.
Uma M Muthurajan

Department of Chemistry and Biochemistry, University of Colorado, Boulder, Boulder, United States

Competing interests
The authors declare that no competing interests exist.
Karolin Luger

Department of Chemistry and Biochemistry, HHMI and University of Colorado, Boulder, Boulder, United States

For correspondence
karolin.luger@colorado.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-5136-5331

Funding

National Cancer Institute (CA218255)

Karolin Luger

Howard Hughes Medical Institute

Karolin Luger

National Institutes of Health (T32GM008759)

Genevieve Roberts

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.