Elaine M. Tobin

Last updated
Elaine M. Tobin
Born
Elaine Munsey

(1944-12-23) December 23, 1944 (age 79)
Louisville, Kentucky
Education Oberlin College, Harvard University
Known for Circadian clock in plants
Partner(s)Allan J. Tobin, [1] J. Philip Thornber [2]
Scientific career
Institutions University of California, Los Angeles

Elaine Munsey Tobin (born December 23, 1944, Louisville, Kentucky) [3] is a professor of molecular, cell, and developmental biology at the University of California, Los Angeles (UCLA). [4] Tobin is recognized as a Pioneer Member of the American Society of Plant Biologists (ASPB). [5]

Contents

Tobin studies how phytochrome photoreceptors interact with the circadian clock in plants, in particular circadian oscillator proteins and the ways in which feedback loops are regulated through gene expression. [4] Tobin identified one of the first two components of the circadian clock in plants, the dawn expressed transcription factor CCA1. [6] [7]  Her lab also showed that CCA1 was necessary for phytochrome response in Arabidopsis thaliana [8] and that one type of regulation involves the phosphorylation of CCA1 by the protein kinase CK2. [7] [9]

Early life and education

Elaine Munsey was born in Louisville, Kentucky on December 23, 1944. [3] Her family had immigrated from Odessa and Lithuania. [1] Munsey's interests included science, mathematics and basketball. She attended the 1960 Democratic National Convention as a volunteer working for Adlai Stevenson II's presidential campaign. While in high school, she also participated in civil rights marches and heard Martin Luther King Jr. speak in Louisville. [1] She graduated from Seneca High School in Louisville in 1962. [10]

She earned her Bachelor of Arts degree from Oberlin College in 1966, majoring in chemistry. [3] After graduation, she spent a summer as an Appalachian Volunteer, working as a community organizer in Wolfe County, Kentucky, as part of Lyndon Johnson's War on Poverty. [1]

She was accepted into the Biology Department at Stanford. She took classes in plant physiology with Winslow Briggs, worked in his laboratory, and transferred to Harvard when Briggs took a professorship there. In 1968 she married Allan J. Tobin. They spent a year at the Weizmann Institute of Science in Israel, where Elaine Tobin worked with plant geneticist Ezra Galun. [1] After returning to North America, she completed her Ph.D. in Biology at Harvard University in 1972. [3] She later married J. Philip Thornber. [2]

Career

In 1973 Tobin went to Brandeis University, where she did postdoctoral work with Attila Klein, on the influence of light on the development of plants. In 1975 she was hired in the Biology Department at University of California, Los Angeles (UCLA). Support was sparse, but she was able to get funding for basic research on plants from the National Institutes of Health (NIH). She was able to obtain laboratory space previously used by retiring professor Karl Hamner. [11]

As a student with Winslow Briggs, Tobin had been introduced to the effects of phytochrome on flowering and to the work of Karl Hamner on circadian rhythms and flowering. [1] Circadian rhythms in plants help them to coordinate with external light/dark cycles. Anticipating dawn, dusk, and seasonal day length allows plants to more effectively regulate both daily and seasonal activities, including the movement of leaves and petals, the opening of stomata for photosynthesis, stem growth, and the development of flowers. [12]

Tobin first used Lemna gibba (duckweed) and later Arabidopsis thaliana (cress) as model plant systems to study light regulation of gene expression in plants, examining interactions between phytochrome photoreceptors, genes, and circadian rhythms. [13] Tobin was able to isolate poly(A) RNA from duckweed, expose slab gels to x-ray film, and show that while some mRNAs decreased in light, others increased. [13]

In 1984, postdoctoral student Jane Silverthorne and Tobin demonstrated that photoreceptors in plants could affect the transcription of specific genes. Light-harvesting chlorophyll a/b-binding (LHCB) protein sequences from Lemna gibba were low in darkness but could be rapidly and reversibly restored by light exposure. [13] Tobin's group also demonstrated phytochrome regulation of LHCB proteins (also known as cab genes) in Arabidopsis. [13] [14] [15] By growing duckweed heterotrophically in the dark, and exposing it briefly to red and far-red light, Tobin demonstrated the effects of phytochromes on plant growth and transcription in rcbs genes. [16]

In a series of experiments beginning in 1993, Tobin's lab described DNA-binding activity with an affinity for LHCB in plant cells. Using a DNA fragment, they screened the Arabidopsis expression library, and cloned a protein with relevant binding activity, which they named CCA1. They showed that Circadian Clock Associated 1 (CCA1) was necessary for phytochrome response in Arabidopsis thaliana. [8] Reports on the activity of CCA1 and a closely related gene (LHY) from George Coupland were submitted together to Cell in 1998. [1] The two genes were the first two components of the circadian clock or central oscillator mechanism in plants to be identified. [6] [7] Among many other studies of the regulation and function of CCA1, Tobin has determined that one method of clock regulation involves the phosphorylation of CCA1 by the protein kinase CK2. [17]

Elaine M. Tobin retired from teaching in 2014. [1]

Selected research

Related Research Articles

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<span class="mw-page-title-main">Cryptochrome</span> Class of photoreceptors in plants and animals

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Timing of CAB expression 1 is a protein that in Arabidopsis thaliana is encoded by the TOC1 gene. TOC1 is also known as two-component response regulator-like APRR1.

Circadian Clock Associated 1 (CCA1) is a gene that is central to the circadian oscillator of angiosperms. It was first identified in Arabidopsis thaliana in 1993. CCA1 interacts with LHY and TOC1 to form the core of the oscillator system. CCA1 expression peaks at dawn. Loss of CCA1 function leads to a shortened period in the expression of many other genes.

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Andrew John McWalter Millar, FRS, FRSE is a Scottish chronobiologist, systems biologist, and molecular geneticist. Millar is a professor at The University of Edinburgh and also serves as its chair of systems biology. Millar is best known for his contributions to plant circadian biology; in the Steve Kay lab, he pioneered the use of luciferase imaging to identify circadian mutants in Arabidopsis. Additionally, Millar's group has implicated the ELF4 gene in circadian control of flowering time in Arabidopsis. Millar was elected to the Royal Society in 2012 and the Royal Society of Edinburgh in 2013.

Pseudo-response regulator (PRR) refers to a group of genes that regulate the circadian oscillator in plants. There are four primary PRR proteins that perform the majority of interactions with other proteins within the circadian oscillator, and another (PRR3) that has limited function. These genes are all paralogs of each other, and all repress the transcription of Circadian Clock Associated 1 (CCA1) and Late Elongated Hypocotyl (LHY) at various times throughout the day. The expression of PRR9, PRR7, PRR5 and TOC1/PRR1 peak around morning, mid-day, afternoon and evening, respectively. As a group, these genes are one part of the three-part repressilator system that governs the biological clock in plants.

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The chlorophyll a/b-binding protein gene, otherwise known as the CAB gene, is one of the most thoroughly characterized clock-regulated genes in plants. There are a variety of CAB proteins that are derived from this gene family. Studies on Arabidopsis plants have shed light on the mechanisms of biological clocks under the regulation of CAB genes. Dr. Steve Kay discovered that CAB was regulated by a circadian clock, which switched the gene on in the morning and off in the late afternoon. The genes code for proteins that associate with chlorophyll and xanthophylls. This association aids the absorption of sunlight, which transfers energy to photosystem II to drive photosynthetic electron transport.

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References

  1. 1 2 3 4 5 6 7 8 Tobin, Elaine (20 May 2022). "Adventures in Life and Science, from Light to Rhythms". Annual Review of Plant Biology. 73 (1): 1–16. doi:10.1146/annurev-arplant-090921-091346. ISSN   1543-5008. PMID   35130444. S2CID   246650996.
  2. 1 2 Thornber, J. Philip (2000). "Thirty Years of Fun with Antenna Pigment-Proteins and Photochemical Reaction Centers: A Tribute to the People Who Have Influenced My Career". Discoveries in Plant Biology. Vol. 3. World Scientific. pp. 325–346. doi:10.1142/9789812813503_0017. ISBN   978-981-02-3882-7.
  3. 1 2 3 4 American men & women of science: a biographical directory of today's leaders in physical, biological, and related sciences (24th ed.). Detroit, Mich.: Thomson Gale. 2007. ISBN   978-1-4144-3399-8.
  4. 1 2 "Elaine Tobin – Molecular Biology Institute". University of California, Los Angeles. Retrieved 23 May 2022.
  5. ↑ "ASPB Pioneer Members". American Society of Plant Biologists. Retrieved 23 May 2022.
  6. 1 2 Nohales, Maria A; Kay, Steve A (December 2016). "Molecular mechanisms at the core of the plant circadian oscillator". Nature Structural & Molecular Biology. 23 (12): 1061–1069. doi:10.1038/nsmb.3327. PMC   7750160 . PMID   27922614.
  7. 1 2 3 McClung, CR (12 March 2019). "The Plant Circadian Oscillator". Biology. 8 (1): 14. doi: 10.3390/biology8010014 . PMC   6466001 . PMID   30870980.
  8. 1 2 Salomé, Patrice A.; McClung, C. Robertson (October 2004). "The Arabidopsis thaliana Clock". Journal of Biological Rhythms. 19 (5): 425–435. doi:10.1177/0748730404268112. ISSN   0748-7304. PMID   15534322. S2CID   19023414 . Retrieved 23 May 2022.
  9. ↑ Portolés, Sergi; Más, Paloma (4 November 2010). "The Functional Interplay between Protein Kinase CK2 and CCA1 Transcriptional Activity Is Essential for Clock Temperature Compensation in Arabidopsis". PLOS Genetics. 6 (11): e1001201. doi: 10.1371/journal.pgen.1001201 . PMC   2973838 . PMID   21079791.
  10. ↑ "Hall of Fame". Seneca Forever. Retrieved 23 May 2022.
  11. ↑ Tobin, Elaine (2008). "A Winding Road to a Happy Academic Career" (PDF). ASPB News. 35 (6): 11, 14. Retrieved 25 May 2022.
  12. ↑ Daniel, Xavier; Sugano, Shoji; Tobin, Elaine M. (2 March 2004). "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. 101 (9): 3292–3297. Bibcode:2004PNAS..101.3292D. doi: 10.1073/pnas.0400163101 . ISSN   0027-8424. PMC   365783 . PMID   14978263.
  13. 1 2 3 4 Sage, Linda C. (2 December 2012). "32. Gene regulation". Pigment of the Imagination: A History of Phytochrome Research. Elsevier. pp. 480–515. ISBN   978-0-323-13854-3 . Retrieved 23 May 2022.
  14. ↑ Yakir, Esther; Hilman, Dror; Hassidim, Miriam; Green, Rachel M. (5 November 2007). "Circadian Clock Associated1 Transcript Stability and the Entrainment of the Circadian Clock in Arabidopsis". Plant Physiology. 145 (3): 925–932. doi:10.1104/pp.107.103812. PMC   2048808 . PMID   17873091.
  15. ↑ Tobin, Elaine M. (2016). "My Path from Chemistry to Phytochrome and Circadian Rhythms". Frontiers in Plant Science. 7: 261. doi: 10.3389/fpls.2016.00261 . ISSN   1664-462X. PMC   4791383 . PMID   27014288.
  16. ↑ Fosket, Donald E. (2 December 2012). Plant Growth and Development: A Molecular Approach. Elsevier. ISBN   978-0-12-407792-8 . Retrieved 26 May 2022.
  17. ↑ Krahmer, Johanna; Hindle, Matthew; Perby, Laura K.; Mogensen, Helle K.; Nielsen, Tom H.; Halliday, Karen J.; Ooijen, Gerben van; Bihan, Thierry Le; Millar, Andrew J. (1 January 2022). "The Circadian Clock Gene Circuit Controls Protein and Phosphoprotein Rhythms in Arabidopsis thaliana". Molecular & Cellular Proteomics. 21 (1): 100172. doi:10.1016/j.mcpro.2021.100172. ISSN   1535-9476. PMC   8733343 . PMID   34740825 . Retrieved 24 May 2022.
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