1s57
crystal structure of nucleoside diphosphate kinase 2 from Arabidopsis
Structural highlights
FunctionNDK2_ARATH Major role in the synthesis of nucleoside triphosphates other than ATP. The ATP gamma phosphate is transferred to the NDP beta phosphate via a ping-pong mechanism, using a phosphorylated active-site intermediate. May activate MPK3 and MPK6. May be involved in the regulation of cellular redox state and hydrogen peroxide-mediated MAP kinase signaling.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedIn plants, nucleoside diphosphate kinases (NDPKs) play a key role in the signaling of both stress and light. However, little is known about the structural elements involved in their function. Of the three NDPKs (NDPK1-NDPK3) expressed in Arabidopsis thaliana, NDPK2 is involved in phytochrome-mediated signal transduction. In this study, we found that the binding of dNDP or NTP to NDPK2 strengthens the interaction significantly between activated phytochrome and NDPK2. To better understand the structural basis of the phytochrome-NDPK2 interaction, we determined the X-ray structures of NDPK1, NDPK2, and dGTP-bound NDPK2 from A.thaliana at 1.8A, 2.6A, and 2.4A, respectively. The structures showed that nucleotide binding caused a slight conformational change in NDPK2 that was confined to helices alphaA and alpha2. This suggests that the presence of nucleotide in the active site and/or the evoked conformational change contributes to the recognition of NDPK2 by activated phytochrome. In vitro binding assays showed that only NDPK2 interacted specifically with the phytochrome and the C-terminal regulatory domain of phytochrome is involved in the interaction. A domain swap experiment between NDPK1 and NDPK2 showed that the variable C-terminal region of NDPK2 is important for the activation by phytochrome. The structure of Arabidopsis NDPK1 and NDPK2 showed that the isoforms share common electrostatic surfaces at the nucleotide-binding site, but the variable C-terminal regions have distinct electrostatic charge distributions. These findings suggest that the binding of nucleotide to NDPK2 plays a regulatory role in phytochrome signaling and that the C-terminal extension of NDPK2 provides a potential binding surface for the specific interaction with phytochromes. Structural analysis of Arabidopsis thaliana nucleoside diphosphate kinase-2 for phytochrome-mediated light signaling.,Im YJ, Kim JI, Shen Y, Na Y, Han YJ, Kim SH, Song PS, Eom SH J Mol Biol. 2004 Oct 22;343(3):659-70. PMID:15465053[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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