INVESTIGADORES
GONZALEZ Daniel Hector
artículos
Título:
Redox regulation of plant homeodomain transcription factors
Autor/es:
TRON, ADRIANA E.; BERTONCINI, CARLOS W.; CHAN, RAQUEL L.; GONZALEZ, DANIEL H.
Revista:
JOURNAL OF BIOLOGICAL CHEMISTRY
Editorial:
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Referencias:
Año: 2002 vol. 277 p. 34800 - 34807
ISSN:
0021-9258
Resumen:
Several families of plant transcription factors contain a conserved DNA
binding motif known as the homeodomain. In two of these families, named
Hd-Zip and glabra2, the homeodomain is associated with a leucine
zipper-like dimerization motif. A group of Hd-Zip proteins, namely
Hd-ZipII, contain a set of conserved cysteines within the dimerization
motif and adjacent to it. Incubation of one of these proteins, Hahb-10,
in the presence of thiol-reducing agents such as dithiothreitol or
reduced glutathione produced a significant increase in DNA binding.
Under such conditions, the protein migrated as a monomer in non-reducing
SDS-polyacrylamide gels. Under oxidizing conditions, a significant
proportion of the protein migrated as dimers, suggesting the formation
of intermolecular disulfide bonds. A similar behavior was observed for
the glabra2 protein HAHR1, which also contains two conserved cysteines
within its dimerization domain. Site-directed mutagenesis of the
cysteines to serines indicated that each of them has different roles in
the activation of the proteins. Purified thioredoxin was able to direct
the NADPH-dependent activation of Hahb-10 and HAHR1 in the presence of
thioredoxin reductase. The results suggest that redox conditions may
operate to regulate the activity of these groups of plant transcription
factors within plant cells.