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J. Biol. Chem., Vol. 278, Issue 3, 1612-1617, January 17, 2003
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From the Department of Biochemistry and Molecular Biology,
Georgetown University Medical Center, Washington, D. C. 20057
Dominant negative forms of the phage Mu
repressor, including the mutant Vir repressors, are not only rapidly
degraded by the ClpXP protease but also promote degradation of the
unmodified, wild-type repressor. This trans-targeting of
the wild-type repressor depends upon a determinant within its
C-terminal domain, which is needed for recognition by ClpX. An
environmentally sensitive fluorescent probe
(2-(4'-maleimidylanilino)naphthalene-6-sulfonic acid (MIANS)) attached
to the C terminus of the full-length repressor indicated that Vir
induces the movement of this domain into a more exposed configuration.
Vir also promoted attachment of MIANS to the C terminus of the
repressor at an accelerated rate, and it greatly increased the rate of
phosphorylation of a cAMP-dependent protein kinase motif
attached to the repressor C terminus. While an excess of Vir was needed
to promote repressor phosphorylation at maximal rates, the presence of
ClpX could increase phosphorylation rates at lower Vir levels.
trans-Targeting of the Mu repressor is therefore promoted
by exposing its ClpX recognition determinant, and the action of ClpX
can assist Vir in exposing these determinants.
To whom correspondence should be addressed: Dept. of Biochemistry
and Molecular Biology, School of Medicine, Georgetown University, Box
571455, Washington, D. C. 20057-1421. Tel.: 202-687-1442; Fax:
202-687-7186; E-mail: nakai@bc.georgetown.edu.
This article has been cited by other articles:
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K. R. Marshall-Batty and H. Nakai Activation of a Dormant ClpX Recognition Motif of Bacteriophage Mu Repressor by Inducing High Local Flexibility J. Biol. Chem., April 4, 2008; 283(14): 9060 - 9070. [Abstract] [Full Text] [PDF] |
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D. A. Defenbaugh and H. Nakai A Context-dependent ClpX Recognition Determinant Located at the C Terminus of Phage Mu Repressor J. Biol. Chem., December 26, 2003; 278(52): 52333 - 52339. [Abstract] [Full Text] [PDF] |
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S. B. Neher, R. T. Sauer, and T. A. Baker Distinct peptide signals in the UmuD and UmuD' subunits of UmuD/D' mediate tethering and substrate processing by the ClpXP protease PNAS, November 11, 2003; 100(23): 13219 - 13224. [Abstract] [Full Text] [PDF] |
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