Quaternary Structure Change as a Mechanism for the Regulation of Thymidine Kinase 1-Like Enzymes

• Type of Material: Article
• Authors: Dario Segura-Pena, University of Illinois; Joseph Lichter, Emory University; Manuela Trani, Emory University; Manfred Konrad, Max-Planck-Institute for Biophysical Chemistry; Arnon Lavie, University of Illinois; Stefan Lutz, Emory University
• Language: English
• Date: 2007-12
• Publisher: Elsevier (Cell Press)
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2007 Elsevier Ltd All rights reserved
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.str.2007.09.025
• Title of Journal or Parent Work: Structure
• ISSN: 0969-2126
• Volume: 15
• Issue: 12
• Start Page: 1555
• End Page: 1566
• Grant/Funding Information: M.K. was also supported by the Deutsche Forschungsgemeinschaft and the Max-Planck-Society.; This work was supported in part by NIH grant AI046943 (to D.S.-P., A.L., and M.K.), as well as GM69958 (to J.L., M.T., and S.L.) and by a grant to the Emory Center for AIDS Research (AI050409) from the NIH and by institutional funding from the Emory University HSC.
• Research Categories: Biology, Cell

Abstract

The human cytosolic thymidine kinase (TK) and structurally related TKs in prokaryotes play a crucial role in the synthesis and regulation of the cellular thymidine triphosphate pool. We are now reporting the crystal structures of the TK homotetramer from Thermotoga maritima in four different states, its apo-form, a binary complex with thymidine, as well as the ternary structures with the two substrates (thymidine/AppNHp) and the reaction products (TMP/ADP). In combination with fluorescence spectroscopy and mutagenesis experiments, our results demonstrate that ATP binding is linked to a substantial reorganization of the enzyme quaternary structure, leading to a transition from a closed, inactive conformation to an open, catalytic state. We hypothesize that these structure changes are relevant to enzyme function in situ as part of the catalytic cycle and serve an important role in regulating enzyme activity by amplifying the effects of feedback inhibitor binding.