Importin alpha binding and nuclear localization of PARP-2 is dependent on lysine 36, which is located within a predicted classical NLS

• Published in: BMC cell biology Vol. 9; no. 1; p. 39
• Main Authors: Haenni, Sandra S, Altmeyer, Matthias, Hassa, Paul O, Valovka, Taras, Fey, Monika, Hottiger, Michael O
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 21.07.2008; BioMed Central; BMC
• Subjects: alpha Karyopherins - genetics; alpha Karyopherins - metabolism; Amino Acid Sequence; Animals; Antibiotics, Antineoplastic - metabolism; Cell Line; Cell Nucleus - metabolism; Cell research; Cellular proteins; Fatty Acids, Unsaturated - metabolism; Genetic aspects; Humans; Lysine - metabolism; Methods; Molecular Sequence Data; Mutagenesis, Site-Directed; Nuclear Localization Signals - genetics; Nuclear Localization Signals - metabolism; Physiological aspects; Poly(ADP-ribose) Polymerases - genetics; Poly(ADP-ribose) Polymerases - metabolism; Protein Binding; Protein Isoforms - genetics; Protein Isoforms - metabolism; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Sequence Alignment; Transferases; Switzerland
• ISSN: 1471-2121; 1471-2121
• DOI: 10.1186/1471-2121-9-39

The enzymes responsible for the synthesis of poly-ADP-ribose are named poly-ADP-ribose polymerases (PARP). PARP-2 is a nuclear protein, which regulates a variety of cellular functions that are mainly controlled by protein-protein interactions. A previously described non-conventional bipartite nuclear localization sequence (NLS) lies in the amino-terminal DNA binding domain of PARP-2 between amino acids 1-69; however, this targeting sequence has not been experimentally examined or validated. Using a site-directed mutagenesis approach, we found that lysines 19 and 20, located within a previously described bipartite NLS, are not required for nuclear localization of PARP-2. In contrast, lysine 36, which is located within a predicted classical monopartite NLS, was required for PARP-2 nuclear localization. While wild type PARP-2 interacted with importin alpha3 and to a very weak extent with importin alpha1 and importin alpha5, the mutant PARP-2 (K36R) did not interact with importin alpha3, providing a molecular explanation why PARP-2 (K36R) is not targeted to the nucleus. Our results provide strong evidence that lysine 36 of PARP-2 is a critical residue for proper nuclear targeting of PARP-2 and consequently for the execution of its biological functions.