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Molecular and Cellular Biology, October 1998, p. 5690-5698, Vol. 18, No. 10
ABL-Basic Research Program, National Cancer
Institute-Frederick Cancer Research and Development Center,
Frederick, Maryland 21702-1201
Received 9 February 1998/Returned for modification 27 March
1998/Accepted 15 July 1998
The stability of the p53 tumor suppressor protein is regulated by
interaction with Mdm2, the product of a p53-inducible gene. Mdm2-targeted degradation of p53 depends on the interaction between the
two proteins and is mediated by the proteasome. We show here that in
addition to the N-terminal Mdm2 binding domain, the C terminus of p53
participates in the ability of p53 to be degraded by Mdm2. In contrast,
alterations in the central DNA binding domain of p53, which change the
conformation of the p53 protein, do not abrogate the sensitivity of the
protein to Mdm2-mediated degradation. The importance of the C-terminal
oligomerization domain to Mdm2-targeted degradation of p53 is likely to
reflect the importance of oligomerization of the full-length p53
protein for interaction with Mdm2, as previously shown in vitro.
Interestingly, the extreme C-terminal region of p53,
outside the oligomerization domain, was also shown to be necessary for
efficient degradation, and deletion of this region stabilized the
protein without abrogating its ability to bind to Mdm2. Mdm2-resistant
p53 mutants were not further stabilized following DNA damage,
supporting a role for Mdm2 as the principal regulator of p53 stability
in cells. The extreme C terminus of the p53 protein has previously been
shown to contain several regulatory elements, raising the possibility
that either allosteric regulation of p53 by this domain or interaction
between this region and a third protein plays a role in determining the
sensitivity of p53 to Mdm2-directed degradation.
0270-7306/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Regulation of Mdm2-Directed Degradation by the
C Terminus of p53
*
Corresponding author. Mailing address: ABL Basic
Research Program, NCI-FCRDC, Building 560, Room 22-96, P.O. Box B,
Frederick, MD 21702-1201. Phone: (301) 846-1726. Fax: (301) 846-1666. E-mail: vousden{at}ncifcrf.gov.
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