Structural insights into SAM domain-mediated tankyrase oligomerization.
Tankyrase 1 (TNKS1; a.k.a. ARTD5) and tankyrase 2 (TNKS2; a.k.a ARTD6) are highly homologous poly(ADP-ribose) polymerases (PARPs) that function in a wide variety of cellular processes including Wnt signaling, Src signaling, Akt signaling, Glut4 vesicle translocation, telomere length regulation, and centriole and spindle pole maturation. Tankyrase proteins include a sterile alpha motif (SAM) domain that undergoes oligomerization in vitro and in vivo. However, the SAM domains of TNKS1 and TNKS2 have not been structurally characterized and the mode of oligomerization is not yet defined. Here we model the SAM domain-mediated oligomerization of tankyrase. The structural model, supported by mutagenesis and NMR analysis, demonstrates a helical, homotypic head-to-tail polymer that facilitates TNKS self-association. Furthermore, we show that TNKS1 and TNKS2 can form (TNKS1 SAM-TNKS2 SAM) hetero-oligomeric structures mediated by their SAM domains. Though wild-type tankyrase proteins have very low solubility, model-based mutations of the SAM oligomerization interface residues allowed us to obtain soluble TNKS proteins. These structural insights will be invaluable for the functional and biophysical characterization of TNKS1/2, including the role of TNKS oligomerization in protein poly(ADP-ribosyl)ation (PARylation) and PARylation-dependent ubiquitylation.
Department of Biochemistry, University of Washington, Seattle, Washington, 98195.|Department of Biological Structure, University of Washington, Seattle, Washington, 98195.
Paul A
PA
DaRosa
Department of Biochemistry, University of Washington, Seattle, Washington, 98195.|Howard Hughes Medical Institute, University of Washington, Seattle, Washington, 98195.
Sergey
S
Ovchinnikov
Department of Biological Structure, University of Washington, Seattle, Washington, 98195.
Wenqing
W
Xu
Department of Biochemistry, University of Washington, Seattle, Washington, 98195.
Rachel E
RE
Klevit
D000818:Animals; D006801:Humans; D051379:Mice; D000072417:Protein Domains; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D038501:Tankyrases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D038501:Tankyrases; C437334:TNKS2 protein, human; C498822:Tnks protein, mouse; C511054:tankyrase-2, mouse; C418109:TNKS protein, human
PARP; PARP5; PARylation; SAM; molecular model; oligomerization; protein poly(ADP-ribosyl)ation; sterile alpha motif; tankyrase