OPEN ACCESS ARTICLE

This Article Free via Open Access: OA OA Full Text Full Text (PDF) OA All Versions of this Article: 18/10/2622    most recent tpc.105.037119v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (15) Citing Articles via Google Scholar Google Scholar Articles by Pasternak, O. Articles by Jaskolski, M. Search for Related Content PubMed PubMed Citation Articles by Pasternak, O. Articles by Jaskolski, M. Agricola Articles by Pasternak, O. Articles by Jaskolski, M.

Crystal Structure of Vigna radiata Cytokinin-Specific Binding Protein in Complex with Zeatin^[OA]

^a Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61704 Poznan, Poland
^b Institute of Technical Biochemistry, Technical University of Lodz, 90924 Lodz, Poland
^c Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa 1990195, Japan
^d Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo 1130032, Japan
^e Laboratory of Protein Engineering, Institute of Biochemistry and Molecular Biology, University of Wroclaw, 50137 Wroclaw, Poland
^f Department of Crystallography, Faculty of Chemistry, A. Mickiewicz University, 60780 Poznan, Poland

¹ To whom correspondence should be addressed. E-mail mariuszj{at}amu.edu.pl; fax 48-61-865-8008.

The cytosolic fraction of Vigna radiata contains a 17-kD protein that binds plant hormones from the cytokinin group, such as zeatin. Using recombinant protein and isothermal titration calorimetry as well as fluorescence measurements coupled with ligand displacement, we have reexamined the K_d values and show them to range from 10^–6 M (for 4PU30) to 10^–4 M (for zeatin) for 1:1 stoichiometry complexes. In addition, we have crystallized this cytokinin-specific binding protein (Vr CSBP) in complex with zeatin and refined the structure to 1.2 Å resolution. Structurally, Vr CSBP is similar to plant pathogenesis-related class 10 (PR-10) proteins, despite low sequence identity (<20%). This unusual fold conservation reinforces the notion that classic PR-10 proteins have evolved to bind small-molecule ligands. The fold consists of an antiparallel ß-sheet wrapped around a C-terminal -helix, with two short -helices closing a cavity formed within the protein core. In each of the four independent CSBP molecules, there is a zeatin ligand located deep in the cavity with conserved conformation and protein–ligand interactions. In three cases, an additional zeatin molecule is found in variable orientation but with excellent definition in electron density, which plugs the entrance to the binding pocket, sealing the inner molecule from contact with bulk solvent.

This article has been cited by other articles:

				P. Zubini, B. Zambelli, F. Musiani, S. Ciurli, P. Bertolini, and E. Baraldi The RNA Hydrolysis and the Cytokinin Binding Activities of PR-10 Proteins Are Differently Performed by Two Isoforms of the Pru p 1 Peach Major Allergen and Are Possibly Functionally Related Plant Physiology, July 1, 2009; 150(3): 1235 - 1247. [Abstract] [Full Text] [PDF]

				Y. Ma, I. Szostkiewicz, A. Korte, D. Moes, Y. Yang, A. Christmann, and E. Grill Regulators of PP2C Phosphatase Activity Function as Abscisic Acid Sensors Science, May 22, 2009; 324(5930): 1064 - 1068. [Abstract] [Full Text] [PDF]

				A. Ilari, S. Franceschini, A. Bonamore, F. Arenghi, B. Botta, A. Macone, A. Pasquo, L. Bellucci, and A. Boffi Structural Basis of Enzymatic (S)-Norcoclaurine Biosynthesis J. Biol. Chem., January 9, 2009; 284(2): 897 - 904. [Abstract] [Full Text] [PDF]