Phytochrome is a regulatory master switch that controls gene expression in response to fight signals from the environment. The long term goal of the proposed research is to define the molecular mechanism by which this regulation is exerted. The specific objectives of this proposal are: (a) to identify sequence and structural features of the phytochrome A molecule responsible for its regulatory action; and (b) to define regulatory elements in the multidomain phyA gene promoter Arabidopsis responsible for differential expression from multiple transcription start sites. The experimental approaches will include: (a) biochemical analysis to assess the possibility that Avena phytochrome A has protein kinase activity similar to prokaryotic sensor proteins; (b) overexpression of mutagenized Avena phytochrome A in transgenic Arabidopsis and microorganisms to identify structurally and functionally important domains and residues; (c) microinjection of mutagenized phytochrome A into phytochrome-deficient transgenic Arabidopsis cells carrying phytochrome-responsive promoter-reporter fusion constructs to identify functionally critical sequences in the photoreceptor by transient expression assay; (d) production of homogeneous phytochrome A preparations by overexpression in microorganisms for X-ray crystallographic analysis; and (e) deletion and sequence substitution analysis of the Arabidopsis phyA promoter in transgenic Arabidopsis to delineate cis-acting DNA sequences involved in the regulation of this complex promoter. The significance of this research is that it will help define the mechanism by which a central regulatory molecule controls gene expression. Because phytochrome appears as yet to have no molecular counterpart in other eukaryotes, elucidation of this mechanism has the potential to broaden our understanding of the strategies used by eukaryotic cells to regulate gene expression in response to environmental stimuli.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM047475-02
Application #
3306979
Study Section
Molecular Cytology Study Section (CTY)
Project Start
1992-09-30
Project End
1996-08-31
Budget Start
1993-09-01
Budget End
1994-08-31
Support Year
2
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of California Berkeley
Department
Type
Schools of Earth Sciences/Natur
DUNS #
094878337
City
Berkeley
State
CA
Country
United States
Zip Code
94704
Ni, Weimin; Xu, Shou-Ling; González-Grandío, Eduardo et al. (2017) PPKs mediate direct signal transfer from phytochrome photoreceptors to transcription factor PIF3. Nat Commun 8:15236
Dalton, Jutta C; Bätz, Ulrike; Liu, Jason et al. (2016) A Modified Reverse One-Hybrid Screen Identifies Transcriptional Activation Domains in PHYTOCHROME-INTERACTING FACTOR 3. Front Plant Sci 7:881
Martín, Guiomar; Leivar, Pablo; Ludevid, Dolores et al. (2016) Phytochrome and retrograde signalling pathways converge to antagonistically regulate a light-induced transcriptional network. Nat Commun 7:11431
Soy, Judit; Leivar, Pablo; González-Schain, Nahuel et al. (2016) Molecular convergence of clock and photosensory pathways through PIF3-TOC1 interaction and co-occupancy of target promoters. Proc Natl Acad Sci U S A 113:4870-5
Cordeiro, André M; Figueiredo, Duarte D; Tepperman, James et al. (2016) Rice phytochrome-interacting factor protein OsPIF14 represses OsDREB1B gene expression through an extended N-box and interacts preferentially with the active form of phytochrome B. Biochim Biophys Acta 1859:393-404
Pfeiffer, Anne; Shi, Hui; Tepperman, James M et al. (2014) Combinatorial complexity in a transcriptionally centered signaling hub in Arabidopsis. Mol Plant 7:1598-1618
Martínez-García, Jaime F; Gallemí, Marçal; Molina-Contreras, María José et al. (2014) The shade avoidance syndrome in Arabidopsis: the antagonistic role of phytochrome a and B differentiates vegetation proximity and canopy shade. PLoS One 9:e109275
Ni, Weimin; Xu, Shou-Ling; Tepperman, James M et al. (2014) A mutually assured destruction mechanism attenuates light signaling in Arabidopsis. Science 344:1160-1164
Ni, Weimin; Xu, Shou-Ling; Chalkley, Robert J et al. (2013) Multisite light-induced phosphorylation of the transcription factor PIF3 is necessary for both its rapid degradation and concomitant negative feedback modulation of photoreceptor phyB levels in Arabidopsis. Plant Cell 25:2679-98
Zhang, Yu; Mayba, Oleg; Pfeiffer, Anne et al. (2013) A quartet of PIF bHLH factors provides a transcriptionally centered signaling hub that regulates seedling morphogenesis through differential expression-patterning of shared target genes in Arabidopsis. PLoS Genet 9:e1003244

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