TY - JOUR
T1 - Structural relationships between diverse cis-acting elements are critical for the functional properties of a rbcS minimal light regulatory unit
AU - López-Ochoa, Luisa
AU - Acevedo-Hernández, Gustavo
AU - Martínez-Hernández, Aída
AU - Argüello-Astorga, Gerardo
AU - Herrera-Estrella, Luis
N1 - Funding Information:
This project was supported in part by the following grants CONACyT-SEP 43979 and HHMI (12348739) to LHE. LLO is grateful to CONACYT and CONCYTEG for a PhD fellowship.
PY - 2007/12
Y1 - 2007/12
N2 - Light-regulation of photosynthesis-associated nuclear genes is mediated by multipartite cis-regulatory units located in their promoter regions. The combination, spacing, and relative orientation of transcription factor binding sites in these units influences the assembly of specific multiprotein complexes that control gene expression. In this work, the functional architecture of the conserved modular array 5 (CMA5), a previously characterized minimal light-regulatory unit of rbcS gene promoters, has been analysed. With the aim of defining the sequences of CMA5 that, besides the I- and G-box elements, are essential for CMA5 responsiveness to light and chloroplast-derived signals, a series of mutations affecting the sequences flanking these elements was performed. It was found that an I-box associated module, named IbAM5, is essential for CMA5 functionality and is able to bind nuclear proteins in vitro. The spacing requirements of the I- and G-box elements in achieving adequate combinatorial interaction were also studied as well as the effect of interchanging the relative position of these elements in the native rbcS promoter arrangement. The results show that helical phasing and distance between the I- and G-box motifs are critical to determine the functionality and transcriptional strength of CMA5. Furthermore, it is shown that the relative position of the IbAM5/I-box composite element and the G-box element is not critical for the enhancer activity of CMA5, as long as the proper distance between them is maintained. Taken together, these results suggest that the light-responsive, plastid-dependent activity of CMA5 requires the synergistic interaction of several DNA-binding transcription factors assembled in a higher-order nucleoprotein complex.
AB - Light-regulation of photosynthesis-associated nuclear genes is mediated by multipartite cis-regulatory units located in their promoter regions. The combination, spacing, and relative orientation of transcription factor binding sites in these units influences the assembly of specific multiprotein complexes that control gene expression. In this work, the functional architecture of the conserved modular array 5 (CMA5), a previously characterized minimal light-regulatory unit of rbcS gene promoters, has been analysed. With the aim of defining the sequences of CMA5 that, besides the I- and G-box elements, are essential for CMA5 responsiveness to light and chloroplast-derived signals, a series of mutations affecting the sequences flanking these elements was performed. It was found that an I-box associated module, named IbAM5, is essential for CMA5 functionality and is able to bind nuclear proteins in vitro. The spacing requirements of the I- and G-box elements in achieving adequate combinatorial interaction were also studied as well as the effect of interchanging the relative position of these elements in the native rbcS promoter arrangement. The results show that helical phasing and distance between the I- and G-box motifs are critical to determine the functionality and transcriptional strength of CMA5. Furthermore, it is shown that the relative position of the IbAM5/I-box composite element and the G-box element is not critical for the enhancer activity of CMA5, as long as the proper distance between them is maintained. Taken together, these results suggest that the light-responsive, plastid-dependent activity of CMA5 requires the synergistic interaction of several DNA-binding transcription factors assembled in a higher-order nucleoprotein complex.
KW - Enhancer element
KW - Gene regulation
KW - Light regulation
KW - Nuclear-plastid signalling
KW - Photosynthesis genes
KW - Promoter architecture
UR - http://www.scopus.com/inward/record.url?scp=40049101272&partnerID=8YFLogxK
U2 - 10.1093/jxb/erm307
DO - 10.1093/jxb/erm307
M3 - Article
C2 - 18182441
AN - SCOPUS:40049101272
SN - 0022-0957
VL - 58
SP - 4397
EP - 4406
JO - Journal of Experimental Botany
JF - Journal of Experimental Botany
IS - 15-16
ER -