Previous Article | Next Article ![]()
Molecular and Cellular Biology, September 1998, p. 5478-5484, Vol. 18, No. 9
Institute for Genetic Medicine and Department
of Biochemistry and Molecular Biology, University of Southern
California School of Medicine, Los Angeles, California
90033,1 and
Howard Hughes Medical
Institute, Fred Hutchinson Cancer Research Center, Seattle,
Washington 981042
Received 10 November 1997/Returned for modification 15 December
1997/Accepted 8 May 1998
The MyoD family of basic helix-loop-helix (bHLH) proteins is
required for myogenic determination and differentiation. The basic
region carries the myogenic code and DNA binding specificity, while the
N terminus contains a potent transcriptional activation domain.
Myogenic activation is abolished when the basic region, bound to a
myogenic E box, carries a mutation of Ala-114. It has been proposed
that DNA binding of the MyoD basic region leads to recruitment of a
recognition factor that unmasks the activation domain. Here we
demonstrate that an A114N mutant exhibits an altered conformation in
the basic region and that this local conformational difference can lead
to a more global change affecting the conformation of the activation
domain. This suggests that the deleterious effects of this class of
mutations may result directly from defective conformation. Thus, the
activation domain is unmasked only upon DNA binding by the correct
basic region. Such a coupled conformational relationship may have
evolved to restrict myogenic specificity to a small number of bHLH
proteins among many with diverse functions yet with DNA binding
specificities known to be similar.
0270-7306/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Intramolecular Regulation of MyoD Activation Domain
Conformation and Function
*
Corresponding author. Mailing address: Institute for
Genetic Medicine and Department of Biochemistry and Molecular
Biology, University of Southern California School of Medicine, 2250 Alcazar St., Los Angeles, CA 90033. Phone: (323) 442-1145. Fax: (323) 442-2764. E-mail: kedes{at}hsc.usc.edu.
J.H. dedicates this paper to the memory of Man-Hua Wu.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»