This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Google Scholar
Right arrow Articles by Kindsmüller, K.
Right arrow Articles by Dobner, T.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kindsmüller, K.
Right arrow Articles by Dobner, T.

 Previous Article  |  Next Article 

Journal of Virology, September 2009, p. 9045-9056, Vol. 83, No. 18
0022-538X/09/$08.00+0     doi:10.1128/JVI.00728-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

A 49-Kilodalton Isoform of the Adenovirus Type 5 Early Region 1B 55-Kilodalton Protein Is Sufficient To Support Virus Replication{triangledown}

Kathrin Kindsmüller,2,# Sabrina Schreiner,1,# Florian Leinenkugel,1 Peter Groitl,1 Elisabeth Kremmer,3 and Thomas Dobner1*

Heinrich-Pette-Institute for Experimental Virology and Immunology, Martinistr. 52, 20251 Hamburg, Germany,1 Institute of Medical Microbiology and Hygiene, University Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany,2 Helmholtz Zentrum München, Institute of Molecular Immunology, Marchioninistr. 25, 81377 Munich, Germany3

Received 8 April 2009/ Accepted 1 July 2009

The adenovirus type 5 (Ad5) early region 1B 55-kDa (E1B-55K) protein is a multifunctional regulator of cell-cycle-independent virus replication that participates in many processes required for maximal virus production. As part of a study of E1B-55K function, we generated the Ad5 mutant H5pm4133, carrying stop codons after the second and seventh codons of the E1B reading frame, thereby eliminating synthesis of the full-length 55K product and its smaller derivatives. Unexpectedly, phenotypic studies revealed that H5pm4133 fully exhibits the characteristics of wild-type (wt) Ad5 in all assays tested. Immunoblot analyses demonstrated that H5pm4133 and wt Ad5 produce very low levels of two distinct polypeptides in the 48- to 49-kDa range, which lack the amino-terminal region but contain segments from the central and carboxy-terminal part of the 55K protein. Genetic and biochemical studies with different Ad5 mutants show that at least one of these isoforms consists of two closely migrating polypeptides of 433 amino acid residues (433R) and 422R, which are produced by translation initiation at two downstream AUG codons of the 55K reading frame. Significantly, a virus mutant producing low levels of the 433R isoform alone replicated to levels comparable to those of wt Ad5, demonstrating that this polypeptide provides essentially all functions of E1B-55K required to promote maximal virus growth in human tumor cells. Altogether, these results extend previous findings that the wt Ad5 E1B region encodes a series of smaller isoforms of E1B-55K and demonstrate that very low levels of at least one of these novel proteins (E1B-433R) are sufficient for a productive infection.

* Corresponding author. Mailing address: Heinrich-Pette-Institute for Experimental Virology and Immunology, Martinistr. 52, 20251 Hamburg, Germany. Phone: 49 40 48051 301. Fax: 49 40 48051 302. E-mail: thomas.dobner{at}hpi.uni-hamburg.de

{triangledown} Published ahead of print on 8 July 2009.

# These authors contributed equally to this work.

Journal of Virology, September 2009, p. 9045-9056, Vol. 83, No. 18
0022-538X/09/$08.00+0     doi:10.1128/JVI.00728-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»