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From Proteopedia
Cryo-EM structure of human tankyrase 2 SAM-PARP filament (G1032W mutant)
Structural highlights
FunctionTNKS2_HUMAN Poly-ADP-ribosyltransferase involved in various processes such as Wnt signaling pathway, telomere length and vesicle trafficking. Acts as an activator of the Wnt signaling pathway by mediating poly-ADP-ribosylation of AXIN1 and AXIN2, 2 key components of the beta-catenin destruction complex: poly-ADP-ribosylated target proteins are recognized by RNF146, which mediates their ubiquitination and subsequent degradation. Also mediates poly-ADP-ribosylation of BLZF1 and CASC3, followed by recruitment of RNF146 and subsequent ubiquitination. Mediates poly-ADP-ribosylation of TERF1, thereby contributing to the regulation of telomere length. May also regulate vesicle trafficking and modulate the subcellular distribution of SLC2A4/GLUT4-vesicles.[1] [2] [3] [4] Publication Abstract from PubMedThe poly-ADP-ribosyltransferase tankyrase (TNKS, TNKS2) controls a wide range of disease-relevant cellular processes, including WNT-beta-catenin signalling, telomere length maintenance, Hippo signalling, DNA damage repair and glucose homeostasis(1,2). This has incentivized the development of tankyrase inhibitors. Notwithstanding, our knowledge of the mechanisms that control tankyrase activity has remained limited. Both catalytic and non-catalytic functions of tankyrase depend on its filamentous polymerization(3-5). Here we report the cryo-electron microscopy reconstruction of a filament formed by a minimal active unit of tankyrase, comprising the polymerizing sterile alpha motif (SAM) domain and its adjacent catalytic domain. The SAM domain forms a novel antiparallel double helix, positioning the protruding catalytic domains for recurring head-to-head and tail-to-tail interactions. The head interactions are highly conserved among tankyrases and induce an allosteric switch in the active site within the catalytic domain to promote catalysis. Although the tail interactions have a limited effect on catalysis, they are essential to tankyrase function in WNT-beta-catenin signalling. This work reveals a novel SAM domain polymerization mode, illustrates how supramolecular assembly controls catalytic and non-catalytic functions, provides important structural insights into the regulation of a non-DNA-dependent poly-ADP-ribosyltransferase and will guide future efforts to modulate tankyrase and decipher its contribution to disease mechanisms. Structural basis of tankyrase activation by polymerization.,Pillay N, Mariotti L, Zaleska M, Inian O, Jessop M, Hibbs S, Desfosses A, Hopkins PCR, Templeton CM, Beuron F, Morris EP, Guettler S Nature. 2022 Dec;612(7938):162-169. doi: 10.1038/s41586-022-05449-8. Epub 2022 , Nov 23. PMID:36418402[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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