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

J. Biol. Chem., Vol. 280, Issue 34, 30291-30300, August 26, 2005

This Article Full Text Full Text (PDF) All Versions of this Article: 280/34/30291    most recent M504122200v1 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 HighWire Citing Articles via Google Scholar Google Scholar Articles by Satheshkumar, P. S. Articles by Savithri, H. S. Search for Related Content PubMed PubMed Citation Articles by Satheshkumar, P. S. Articles by Savithri, H. S. Social Bookmarking                      What's this?

"Natively Unfolded" VPg Is Essential for Sesbania Mosaic Virus Serine Protease Activity^*

Panayampalli Subbian Satheshkumar, Pananghat Gayathri¶, Kasaragod Prasad¶, and Handanahal Subbarao Savithri||

From the Department of Biochemistry and the ^¶Molecular Biophysics Unit, Indian Institute of Science, Bangalore-560 012, India

Polyprotein processing is a major strategy used by many plant and animal viruses to maximize the number of protein products obtainable from a single open reading frame. In Sesbania mosaic virus, open reading frame-2 codes for a polyprotein that is cleaved into different functional proteins in cis by the N-terminal serine protease domain. The soluble protease domain lacking 70-amino-acid residues from the N terminus (N70Pro, where Pro is protease) was not active in trans. Interestingly, the protease domain exhibited trans-catalytic activity when VPg (viral protein genome-linked) was present at the C terminus. Bioinformatic analysis of VPg primary structure suggested that it could be a disordered protein. Biophysical studies validated this observation, and VPg resembled "natively unfolded" proteins. CD spectral analysis showed that the N70Pro-VPg fusion protein had a characteristic secondary structure with a 230 nm positive CD peak. Mutation of Trp-43 in the VPg domain to phenylalanine abrogated the positive peak with concomitant loss in cis- and trans-proteolytic activity of the N70Pro domain. Further, deletion of VPg domain from the polyprotein completely abolished proteolytic processing. The results suggested a novel mechanism of activation of the protease, wherein the interaction between the natively unfolded VPg and the protease domains via aromatic amino acid residues alters the conformation of the individual domains and the active site of the protease. Thus, VPg is an activator of protease in Sesbania mosaic virus, and probably by this mechanism, the polyprotein processing could be regulated in planta.

Received for publication, April 15, 2005 , and in revised form, June 7, 2005.

^* This work was supported by the Council of Scientific and Industrial Research and the Department of Biotechnology, New Delhi, India. 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.

Recipients of Council of Scientific and Industrial Research senior research fellowships.

^|| To whom correspondence should be addressed. Tel.: 91-80-23601561; Fax: 91-80-23600814; E-mail: bchss{at}biochem.iisc.ernet.in.

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

This article has been cited by other articles:

				R. Grzela, E. Szolajska, C. Ebel, D. Madern, A. Favier, I. Wojtal, W. Zagorski, and J. Chroboczek Virulence Factor of Potato Virus Y, Genome-attached Terminal Protein VPg, Is a Highly Disordered Protein J. Biol. Chem., January 4, 2008; 283(1): 213 - 221. [Abstract] [Full Text] [PDF]