Synergistic Binding of bHLH Transcription Factors to the Promoter of the Maize NADP-ME Gene Used in C4 Photosynthesis Is Based on an Ancient Code Found in the Ancestral C3 State.
Serra, Tânia S
Molecular biology and evolution
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Borba, A. R., Serra, T. S., Górska, A., Gouveia, P., Cordeiro, A. M., Reyna-Llorens, I., Knerová, J., et al. (2018). Synergistic Binding of bHLH Transcription Factors to the Promoter of the Maize NADP-ME Gene Used in C4 Photosynthesis Is Based on an Ancient Code Found in the Ancestral C3 State.. Molecular biology and evolution, 35 (7), 1690-1705. https://doi.org/10.1093/molbev/msy060
C4 photosynthesis has evolved repeatedly from the ancestral C3 state to generate a carbon concentrating mechanism that increases photosynthetic efficiency. This specialised form of photosynthesis is particularly common in the PACMAD clade of grasses, and is used by many of the world's most productive crops. The C4 cycle is accomplished through cell-type specific accumulation of enzymes but cis-elements and transcription factors controlling C4 photosynthesis remain largely unknown. Using the NADP-Malic Enzyme (NADP-ME) gene as a model we tested whether mechanisms impacting on transcription in C4 plants evolved from ancestral components found in C3 species. Two basic Helix-Loop-Helix (bHLH) transcription factors, ZmbHLH128 and ZmbHLH129, were shown to bind the C4 NADP-ME promoter from maize. These proteins form heterodimers and ZmbHLH129 impairs trans-activation by ZmbHLH128. Electrophoretic mobility shift assays indicate that a pair of cis-elements separated by a seven base pair spacer synergistically bind either ZmbHLH128 or ZmbHLH129. This pair of cis-elements is found in both C3 and C4 Panicoid grass species of the PACMAD clade. Our analysis is consistent with this cis-element pair originating from a single motif present in the ancestral C3 state. We conclude that C4 photosynthesis has co-opted an ancient C3 regulatory code built on G-box recognition by bHLH to regulate the NADP-ME gene. More broadly, our findings also contribute to the understanding of gene regulatory networks controlling C4 photosynthesis.
Zea mays, Malate Dehydrogenase, Plant Proteins, Photosynthesis, Gene Expression Regulation, Plant, Basic Helix-Loop-Helix Transcription Factors, Promoter Regions, Genetic
EC FP7 CP (289582)
European Commission Horizon 2020 (H2020) ERC (206409)
External DOI: https://doi.org/10.1093/molbev/msy060
This record's URL: https://www.repository.cam.ac.uk/handle/1810/275352
Attribution 4.0 International
Licence URL: http://creativecommons.org/licenses/by/4.0/
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