IFEVA   02662
INSTITUTO DE INVESTIGACIONES FISIOLOGICAS Y ECOLOGICAS VINCULADAS A LA AGRICULTURA
Unidad Ejecutora - UE
artículos
Título:
The Arabidopsis B-BOX protein BBX25 interacts with HY5, negatively regulating BBX22 expression to suppress seedling photomorphogenesis.
Autor/es:
GANGAPPA SN, CROCCO CD, JOHANSSON H, DATTA S, HETTIARACHCHI C, HOLM M, BOTTO JF.
Revista:
PLANT CELL
Editorial:
AMER SOC PLANT BIOLOGISTS
Referencias:
Lugar: Rockville; Año: 2013 vol. 25 p. 1243 - 1257
ISSN:
1040-4651
Resumen:
ELONGATED HYPOCOTYL5 (HY5) is a basic domain/leucine zipper (bZIP)
transcription factor, central for the regulation of seedling
photomorphogenesis. Here, we identified a B-BOX (BBX)-containing
protein, BBX25/SALT TOLERANCE HOMOLOG, as an interacting partner of HY5,
which has been previously found to physically interact with
CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1). BBX25 physically interacts with
HY5 both in vitro and in vivo. By physiological and genetic approaches,
we showed that BBX25 is a negative regulator of seedling
photomorphogenesis. BBX25 and its homolog BBX24 regulate deetiolation
processes and hypocotyl shade avoidance response in an additive manner.
Moreover, genetic relationships of bbx25 and bbx24 with hy5 and cop1
revealed that BBX25 and BBX24 additively enhance COP1 and suppress HY5
functions. BBX25 accumulates in a light-dependent manner and undergoes
COP1-mediated degradation in dark and light conditions. Furthermore, a
protoplast cotransfection assay showed that BBX24 and BBX25 repress
BBX22 expression by interfering with HY5 transcriptional activity. As
HY5 binds to the BBX22 promoter and promotes its expression, our results
identify a direct mechanism through which the expression of BBX22 is
regulated. We suggest that BBX25 and BBX24 function as transcriptional
corepressors, probably by forming inactive heterodimers with HY5,
downregulating BBX22 expression for the fine-tuning of light-mediated
seedling development.