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

J. Biol. Chem., Vol. 282, Issue 48, 34945-34951, November 30, 2007

This Article Full Text Full Text (PDF) All Versions of this Article: 282/48/34945    most recent M704044200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted 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 Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ye, J. Articles by Rapoport, T. A. Search for Related Content PubMed PubMed Citation Articles by Ye, J. Articles by Rapoport, T. A. Social Bookmarking                      What's this?

Crystal Structure of an Unusual Thioredoxin Protein with a Zinc Finger Domain^*

Jiqing Ye, Seung-Hyun Cho^¶, Jessica Fuselier, Weikai Li, Jon Beckwith^¶1, and Tom A. Rapoport, Howard Hughes Medical Investigator²

From the Howard Hughes Medical Institute and the Departments of Cell Biology and ^¶Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115

Many Gram-negative bacteria have two cytoplasmic thioredoxins, thioredoxin-1 and -2, encoded by the trxA and trxC genes, respectively. Both thioredoxins have the highly conserved WCGPC motif and function as disulfide-bond reductases. However, thioredoxin-2 has unique features: it has an N-terminal motif that binds a zinc ion, and its transcription is under the control of OxyR, which allows it to be up-regulated under oxidative stress. Here, we report the crystal structure of thioredoxin-2 from Rhodobacter capsulatus. The C-terminal region of thioredoxin-2 forms a canonical thioredoxin fold with a central β-sheet consisting of five strands and four flanking -helices on either side. The N-terminal zinc finger is composed of four short β-strands (S1–S4) connected by three short loops (L1–L3). The four cysteines are at loops L1 and L3 and form a tetragonal binding site for a zinc ion. The zinc finger is close to the first β-strand and first -helix of the thioredoxin fold. Nevertheless, the zinc finger may not directly affect the oxidoreductase activity of thioredoxin-2 because the zinc finger is not near the active site of a protomer and because thioredoxin-2 is a monomer in solution. On the basis of structural similarity to the zinc fingers in Npl4 and Vps36, we propose that the N-terminal zinc finger of thioredoxin-2 mediates protein-protein interactions, possibly with its substrates or chaperones.

Received for publication, May 16, 2007 , and in revised form, September 13, 2007.

The atomic coordinates and structure factors (code 2PPT) 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 National Institutes of Health Grants GMO41883 (to J. B.) and GM052586 (to T. A. R.). 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.

¹ American Cancer Society Professor.

² To whom correspondence should be addressed: Dept. of Cell Biology, Howard Hughes Medical Inst., Harvard Medical School, 240 Longwood Ave., Boston, MA 02115. Tel.: 617-432-1612; Fax: 617-432-1190; E-mail: tom_rapoport{at}hms.harvard.edu.

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