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Elaine M. Tobin, Ph.D.

Laboratory Address:
Dept. of M.C.D.Biology
Los Angeles, CA 90095

Work Address:
Dept. of M.C.D.Biology
Los Angeles, CA 90095

Affiliations
Affiliations
Member, Molecular, Cell, and Developmental Biology
Research Interests
CCA1 (CIRCADIAN CLOCK ASSOCIATED 1) is a transcription factor that interacts with a phytochrome regulatory region of a photosynthetic gene of Arabidopsis thaliana. CCA1 is of particular interest because it is involved in both phytochrome and circadian regulation Overexpression of the protein abolishes many different kinds of circadian rhythms including gene expression, leaf movements, photoperiodic flowering, and rhythmic growth of the hypocotyl. It is part of a negative feedback, loop that suppresses its own synthesis. The evidence has shown that it is part of the circadian oscillator itself. Our current work aims to define exactly how it interacts with other proteins and how the functioning of the oscillator is regulated. We have found that phosphorylation of CCA1 by the protein kinase CK2 is one way in which the clock is regulated. Other proteins that can interact with CCA1 are currently being investigated. We are also interested in the molecular basis of the interaction of the phytochrome photoreceptors and circadian rhythms.
Biography

circadian rhythms; phytochrome regulation of gene expression CCA1 (CIRCADIAN CLOCK ASSOCIATED 1) is a transcription factor that interacts with a phytochrome regulatory region of a photosynthetic gene of Arabidopsis thaliana. CCA1 is of particular interest because it is involved in both phytochrome and circadian regulation Overexpression of the protein abolishes many different kinds of circadian rhythms including gene expression, leaf movements, photoperiodic flowering, and rhythmic growth of the hypocotyl. It is part of a negative feedback, loop that suppresses its own synthesis. The evidence has shown that it is part of the circadian oscillator itself. Our current work aims to define exactly how it interacts with other proteins and how the functioning of the oscillator is regulated. We have found that phosphorylation of CCA1 by the protein kinase CK2 is one way in which the clock is regulated. Other proteins that can interact with CCA1 are currently being investigated. We are also interested in the molecular basis of the interaction of the phytochrome photoreceptors and circadian rhythms.

Publications

A selected list of publications:

Daniel, X Sugano, S Tobin, EM   CK2 phosphorylation of CCA1 is necessary for its circadian oscillator function in Arabidopsis Proceedings of the National Academy of Sciences of the United States of America. , 2004; 101(9): 3292-7.
Green, R.M., Tingay, S., Wang, Z.-Y., Tobin E.M.   Circadian rhythms confer a higher level of fitness to Arabidopsis plants, Plant Physiol, 2002; 129: 576-584.
Green, RM Tobin, EM   The role of CCA1 and LHY in the plant circadian clock Developmental cell. , 2002; 2(5): 516-8.
Santiago-Ong, M Green, RM Tingay, S Brusslan, JA Tobin, EM   shygrl1 is a mutant affected in multiple aspects of photomorphogenesis Plant physiology. , 2001; 126(2): 587-600.
Barak, S Tobin, EM Andronis, C Sugano, S Green, RM   All in good time: the Arabidopsis circadian clock Trends in plant science. , 2000; 5(12): 517-22.
Green, RM Tobin, EM   Loss of the circadian clock-associated protein 1 in Arabidopsis results in altered clock-regulated gene expression Proceedings of the National Academy of Sciences of the United States of America. , 1999; 96(7): 4176-9.
Sugano, S Andronis, C Ong, MS Green, RM Tobin, EM   The protein kinase CK2 is involved in regulation of circadian rhythms in Arabidopsis Proceedings of the National Academy of Sciences of the United States of America. , 1999; 96(22): 12362-6.
Wang, ZY Tobin, EM   Constitutive expression of the CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) gene disrupts circadian rhythms and suppresses its own expression Cell. , 1998; 93(7): 1207-17.
Sugano, S Andronis, C Green, RM Wang, ZY Tobin, EM   Protein kinase CK2 interacts with and phosphorylates the Arabidopsis circadian clock-associated 1 protein Proceedings of the National Academy of Sciences of the United States of America. , 1998; 95(18): 11020-5.
Wang, ZY Kenigsbuch, D Sun, L Harel, E Ong, MS Tobin, EM   A Myb-related transcription factor is involved in the phytochrome regulation of an Arabidopsis Lhcb gene The Plant cell. , 1997; 9(4): 491-507.
Weatherwax, SC Ong, MS Degenhardt, J Bray, EA Tobin, EM   The interaction of light and abscisic acid in the regulation of plant gene expression Plant physiology. , 1996; 111(2): 363-70.
Kenigsbuch, D Tobin, EM   A region of the Arabidopis Lhcb1*3 promoter that binds to CA-1 activity is essential for high expression and phytochrome regulation Plant physiology. , 1995; 108(3): 1023-7.
Tobin, E.M., Kehoe, D.M.   Phytochrome regulated gene expression, Sem. Cell Biol, 1994; 5: 335-346.