IIBBA   05544
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BUENOS AIRES
Unidad Ejecutora - UE
artículos
Título:
A segment containing a G-box and an ACGT motif confers differential expression characteristics and responses to the Arabidopsis Cytc-2 gene, encoding an isoform of cytochrome c
Autor/es:
ELINA WELCHEN, IVANA L. VIOLA, HYE JIN KIM, LUCIANA P. PRENDES, RAU´ L N. COMELLI, JONG CHAN HONG AND DANIEL H. GONZALEZ
Revista:
JOURNAL OF EXPERIMENTAL BOTANY
Editorial:
Oxford Journals
Referencias:
Lugar: Oxford; Año: 2008 vol. 60 p. 829 - 845
ISSN:
0022-0957
Resumen:
Sequences required for the expression of Cytc-2 (At4g10040), one of two
cytochrome c genes from Arabidopsis thaliana, were characterized using
plants transformed with deleted and mutagenized promoter fragments
fused to gus. These studies indicated that a region containing a G-box
and an ACGT motif is essential for expression. Mutation of the ACGT
motif causes a complete loss of expression, while mutation of the G-box
causes decreased expression in aerial parts and abolishes expression in
roots and induction by environmental factors. Upstream located site II
elements are required for maximal expression, mainly in reproductive
tissues, and maximal induction by different factors. One-hybrid
screenings allowed the identification of transcription factors from the
bZIP and bHLH families that interact mainly with the G-box. Four of
these factors were able to bind to the Cytc-2 promoter in vitro and in
transactivation assays in Arabidopsis. Analysis of available microarray
data indicated that the bZIP transcription factors share expression
characteristics with the Cytc-2 gene, suggesting that they act as
mediators of its response to tissue-specific, environmental, and
metabolic conditions. Site II elements interact with a TCP family
protein and may co-ordinate the expression of the Cytc-2 gene with that
of other respiratory chain components. A model is proposed for the
evolution of the Cytc-2 gene through the incorporation of a segment
containing a G-box and an ACGT motif into an ancestral gene that
contained site II elements. This may have reduced the importance of
site II elements for basal expression and conferred new responses to
environmental factors.