Regulation of poly(ADP-ribose) polymerase 1 activity by the phosphorylation state of the nuclear NAD biosynthetic enzyme NMN adenylyl transferase 1

doi:10.1073/pnas.0609211104

Regulation of poly(ADP-ribose) polymerase 1 activity by the phosphorylation state of the nuclear NAD biosynthetic enzyme NMN adenylyl transferase 1

*Institute of Biochemistry, Free University Berlin, 14195 Berlin, Germany; and
^†Department of Molecular Biology, University of Bergen, 5020 Bergen, Norway

Edited by Solomon H. Snyder, Johns Hopkins University School of Medicine, Baltimore, MD, and approved December 27, 2006 (received for review October 18, 2006)

Abstract

Nuclear NAD⁺ metabolism constitutes a major component of signaling pathways. It includes NAD⁺-dependent protein deacetylation by members of the Sir2 family and protein modification by poly(ADP-ribose) polymerase 1 (PARP-1). PARP-1 has emerged as an important mediator of processes involving DNA rearrangements. High-affinity binding to breaks in DNA activates PARP-1, which attaches poly(ADP-ribose) (PAR) to target proteins. NMN adenylyl transferases (NMNATs) catalyze the final step of NAD⁺ biosynthesis. We report here that the nuclear isoform NMNAT-1 stimulates PARP-1 activity and binds to PAR. Its overexpression in HeLa cells promotes the relocation of apoptosis-inducing factor from the mitochondria to the nucleus, a process known to depend on poly(ADP-ribosyl)ation. Moreover, NMNAT-1 is subject to phosphorylation by protein kinase C, resulting in reduced binding to PAR. Mimicking phosphorylation, substitution of the target serine residue by aspartate precludes PAR binding and stimulation of PARP-1. We conclude that, depending on its state of phosphorylation, NMNAT-1 binds to activated, automodifying PARP-1 and thereby amplifies poly(ADP-ribosyl)ation.

Footnotes

^‡To whom correspondence should be addressed at:
Molekylærbiologisk Institutt, Universitetet i Bergen, Thormøhlensgt. 55, 5020 Bergen, Norway.
E-mail: mathias.ziegler{at}mbi.uib.no
Author contributions: F.B., C.L., and M.Z. designed research; F.B., C.L., and M.Z. performed research; F.B., C.L., and M.Z. analyzed data; and F.B. and M.Z. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS direct submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0609211104/DC1.
Abbreviations:

NMNAT,

NMN adenylyl transferase;

PAR,

poly(ADP-ribose);

PARP-1,

PAR polymerase 1;

AIF,

apoptosis-inducing factor;

BIM,

bisindolylmaleimide.