HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 283, Issue 18, 12259-12266, May 2, 2008

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 283/18/12259    most recent M710553200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map 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 Google Scholar Articles by Tsumoto, K. Articles by Hirama, M. PubMed PubMed Citation Articles by Tsumoto, K. Articles by Hirama, M. Social Bookmarking                      What's this?

Critical Contribution of Aromatic Rings to Specific Recognition of Polyether Rings

THE CASE OF CIGUATOXIN CTX3C-ABC AND ITS SPECIFIC ANTIBODY 1C49^*

Kouhei Tsumoto¹, Akiko Yokota², Yoshikazu Tanaka, Mihoko Ui³, Takeshi Tsumuraya^¶, Ikuo Fujii^¶, Izumi Kumagai, Yoko Nagumo^||, Hiroki Oguri^||, Masayuki Inoue^||, and Masahiro Hirama^||

From the Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8562, the Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aoba-yama 6-6-11, Sendai 980-8579, the ^¶Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Osaka 599-8570, and the ^||Department of Chemistry, Graduate School of Science, Tohoku University, and Solution Oriented Research for Science and Technology (SORST), Japan Science and Technology Agency, Sendai 980-8578, Japan

To address how proteins recognize polyether toxin compounds, we focused on the interaction between the ABC ring compound of ciguatoxin 3C and its specific antibody, 1C49. Surface plasmon resonance analyses indicated that Escherichia coli-expressed variable domain fragments (Fv) of 1C49 had the high affinity constants and slow dissociation constants typical of antigen-antibody interactions. Linear van't Hoff analyses suggested that the interaction is enthalpy-driven. We resolved the crystal structure of 1C49 Fv bound to ABC ring compound of ciguatoxin 3C at a resolution of 1.7Å. The binding pocket of the antibody had many aromatic rings and bound the antigen by shape complementarity typical of hapten-antibody interactions. Three hydrogen bonds and many van der Waals interactions were present. We mutated several residues of the antibody to Ala, and we used surface plasmon resonance to analyze the interactions between the mutated antibodies and the antigen. This analysis identified Tyr-91 and Trp-96 in the light chain as hot spots for the interaction, and other residues made incremental contributions by conferring enthalpic advantages and reducing the dissociation rate constant. Systematic mutation of Tyr-91 indicated that CH- and - interactions between the aromatic ring at this site and the antigen made substantial contributions to the association, and van der Waals interactions inhibited dissociation, suggesting that aromaticity and bulkiness are critical for the specific recognition of polyether compounds by proteins.

Received for publication, December 28, 2007 , and in revised form, March 6, 2008.

The atomic coordinates and structure factors (code 2E27) have been deposited in the Protein Data Bank, Research Collaboratory for Structural Bioinformatics, Rutgers University, New Brunswick, NJ (http://www.rcsb.org/).

^* This work was supported in part by a SORST project from the Japan Science and Technology Agency, Japan. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains supplemental Figs. S1–S4 and Table S1.

² Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology, Tsukuba Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan.

³ Supported by Research Fellowships of the Japan Society for the Promotion of Science for Young Scientists.

¹ To whom correspondence should be addressed: Tel.: 81-7136-5402; Fax: 81-7136-3601; E-mail: tsumoto{at}k.u-tokyo.ac.jp.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?