INVESTIGADORES
COMELLI Raul Nicolas
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:
WELCHEN, E; VIOLA, IL; KIM HJ; PRENDES, LP; COMELLI, RN; HONG, JC; GONZALEZ, DH
Revista:
JOURNAL OF EXPERIMENTAL BOTANY
Editorial:
OXFORD UNIV PRESS
Referencias:
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.