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

J. Biol. Chem., Vol. 282, Issue 26, 18907-18913, June 29, 2007

This Article Full Text Full Text (PDF) All Versions of this Article: 282/26/18907    most recent M701808200v1 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 Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Cuervo, A. Articles by Oliveira, L. Search for Related Content PubMed PubMed Citation Articles by Cuervo, A. Articles by Oliveira, L. Social Bookmarking                      What's this?

Structural Rearrangements between Portal Protein Subunits Are Essential for Viral DNA Translocation^*

Ana Cuervo¹, Marie-Christine Vaney², Alfred A. Antson, Paulo Tavares³, and Leonor Oliveira⁴

From the Unité de Virologie Moléculaire et Structurale, Unité Mixte de Recherche (UMR) CNRS 2472, UMR Institut National de la Recherche Agronomique (INRA) 1157 and Institut Fédératif de Recherche 115, Bat. 14B, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France and the York Structural Biology Laboratory, Department of Chemistry, University of York, York Y010 5YW, United Kingdom

Transport of DNA into preformed procapsids is a general strategy for genome packing inside virus particles. In most viruses, this task is accomplished by a complex of the viral packaging ATPase with the portal protein assembled at a specialized vertex of the procapsid. Such molecular motor translocates DNA through the central tunnel of the portal protein. A central question to understand this mechanism is whether the portal is a mere conduit for DNA or whether it participates actively on DNA translocation. The most constricted part of the bacteriophage SPP1 portal tunnel is formed by twelve loops, each contributed from one individual subunit. The position of each loop is stabilized by interactions with helix -5, which extends into the portal putative ATPase docking interface. Here, we have engineered intersubunit disulfide bridges between -5s of adjacent portal ring subunits. Such covalent constraint blocked DNA packaging, whereas reduction of the disulfide bridges restored normal packaging activity. DNA exit through the portal in SPP1 virions was unaffected. The data demonstrate that mobility between-5 helices is essential for the mechanism of viral DNA translocation. We propose that the -5 structural rearrangements serve to coordinate ATPase activity with the positions of portal tunnel loops relative to the DNA double helix.

Received for publication, March 1, 2007 , and in revised form, April 9, 2007.

^* This work was funded by a Wellcome Trust fellowship (to A. A. A.) and Action Thématique et Incitative sur Programme from the CNRS (to P. T.). 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 Recipient of a doctoral fellowship from Ministère de l'Education Nationale, de la Recherche et de la Technologie (France).

² Present address: Unité de Virologie Structurale and Unité de Recherche Associée 3015 CNRS Départment de Virologie, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France.

⁴ Supported by post-doctoral fellowships from European Molecular Biology Organization, Fundação para a Ciência e Tecnologia (Portugal), and CNRS.

³ To whom correspondence should be addressed: Unité de Virologie Moléculaire et Structurale, UMR CNRS 2472 and UMR INRA 1157, Bat. 14B, Ave. de la Terrasse, 91198 Gif-sur-Yvette Cedex, France. Tel.: 33-169823860; Fax: 33-169824308; E-mail: tavares{at}vms.cnrs-gif.fr.

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