MCB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
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
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Dick, F. A.
Right arrow Articles by Dyson, N. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Dick, F. A.
Right arrow Articles by Dyson, N. J.

 Previous Article  |  Next Article 

Molecular and Cellular Biology, May 2000, p. 3715-3727, Vol. 20, No. 10
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

Mutagenesis of the pRB Pocket Reveals that Cell Cycle Arrest Functions Are Separable from Binding to Viral Oncoproteins

Frederick A. Dick, Elizabeth Sailhamer, and Nicholas J. Dyson*

MGH Cancer Center, Charlestown, Massachusetts 02129

Received 29 September 1999/Returned for modification 10 November 1999/Accepted 15 February 2000

The pocket domain of pRB is required for pRB to arrest the cell cycle. This domain was originally defined as the region of the protein that is necessary and sufficient for pRB's interaction with adenovirus E1A and simian virus s40 large T antigen. These oncoproteins, and other pRB-binding proteins that are encoded by a variety of plant and animal viruses, use a conserved LXCXE motif to interact with pRB. Similar sequences have been identified in multiple cellular pRB-binding proteins, suggesting that the viruses have evolved to target a highly conserved binding site of pRB that is critical for its function. Here we have constructed a panel of pRB mutants in which conserved amino acids that are predicted to make close contacts with an LXCXE peptide were altered. Despite the conservation of the LXCXE binding site throughout evolution, pRB mutants that lack this site are able to induce a cell cycle arrest in a pRB-deficient tumor cell line. This G1 arrest is overcome by cyclin D-cdk4 complexes but is resistant to inactivation by E7. Consequently, mutants lacking the LXCXE binding site were able to induce a G1 arrest in HeLa cells despite the expression of HPV-18 E7. pRB mutants lacking the LXCXE binding site are defective in binding to adenovirus E1A and human papillomavirus type 16 E7 protein but exhibit wild-type binding to E2F or DP, and they retain the ability to interact with CtIP and HDAC1, two transcriptional corepressors that contain LXCXE-like sequences. Consistent with these observations, the pRB mutants are able to actively repress transcription. These observations suggest that viral oncoproteins depend on the LXCXE-binding site of pRB for interaction to a far greater extent than cellular proteins that are critical for cell cycle arrest or transcriptional repression. Mutation of this binding site allows pRB to function as a cell cycle regulator while being resistant to inactivation by viral oncoproteins.

* Corresponding author. Mailing address: MGH Cancer Center, Building 149, 13th St., Charlestown, MA 02129. Phone: (617) 726-7800. Fax: (617) 726-7808. E-mail: dyson{at}helix.mgh.harvard.edu.

Molecular and Cellular Biology, May 2000, p. 3715-3727, Vol. 20, No. 10
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. J. Virol. Eukaryot. Cell
Microbiol. Mol. Biol. Rev. Clin. Vaccine Immunol. All ASM Journals

Copyright © 2000 by the American Society for Microbiology. All rights reserved.