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Dmitri Nusinow is an American chronobiologist who studies plant circadian rhythms. He currently resides in St. Louis, and his research focus includes a combination of molecular, biochemical, genetic, genomic, and proteomic tools to discover the molecular connections between signaling networks, circadian oscillators, and specific outputs. By combining these methods, he hopes to apply the knowledge elucidated from the Arabidopsis model to other plant species.

Education
In 1998, Nusinow earned his bachelor’s degree in Microbiology and Molecular Genetics at UCLA. During his undergraduate years, he worked in the Jay D. Gralla’s lab and studied in vitro analysis of RNA Pol II transcription in the yeast strain, S.pombe. He continued his education to earn his PhD in Biochemistry and Molecular Biology at UCSF. For his first four years, he attempted to create a quadruple KI (knock-in) mouse that would purify the protein RNA complex of Xist, which plays a key role in dosage compensation in female mammals. The tag did not work, so he shifted his focus to plants and the gene expression necessary for day-length discrimination of photoperiodic flowering. Throughout his graduate school experience, he learned important skills like affinity purification and mass spectrometry that would be play an important role in his future research to elucidate complexes in circadian clocks.

Career
For about six months afterwards, he was a researcher at the Scripps Institute. Until 2011, he completed his postdoctoral research at UCSD with Dr. Steve Kay. In Kay’s lab, he was influenced by fellow post-doc Takato Imaizui to study ELF3 in plants. He then became an Adjunct Professor and Principal Investigator at the Donald Danforth Plant Science Center at Washington University in St. Louis where he resides currently.

Scientific Contributions to Circadian Rhythms in Arabidopsis
In 2007, Nusinow, Sawa, Kay, and Imaizumi identified how Arabidopsis proteins FKF1 and GIGANTEA (GI) helped regulate flowering photoperiods in Arabidopsis. Their interest in these proteins arose when they saw FKF1 and GI had displayed similar peak times of expression during the long days. Subsequently, they isolated Arabidopsis proteins FKF1 and GI in a test tube and showed that blue light induced in vitro formation of FKF1 and GI complex. Through a series of transgenic experiments with Arabidopsis, they determined that this complex positively regulated daytime transcription of CONSTANS (CO), a gene promoting flowering in plants. Their results led to a model of how FKF1 and GI complex regulated flowering photoperiods in Arabidopsis.

Nusinow continued working with Arabidopsis and in 2011, he published a paper in the journal Nature where he identified proteins ELF4, ELF3, and gene LUX form a multi-protein clock complex that directly regulated growth in Arabidopsis. Nusinow named it “evening complex” after identifying the complex peaked at dusk, and through a series of transgenic experiments, he proved that ELF4, ELF3, and LUX were required for proper expression of PIF4 and PIF5, two transcription factors critical for regulating hypocotyl growth Arabidopsis seedlings.

In 2015 – 2016, Nusinow and his colleagues identified a protein that was repeatedly associated with the evening complex in AP-MS analysis of the plant circadian clock. Nusinow found that the protein, which he named PCH1 (Photoperiodic Control of Hypocotyl), reduces hypotocotyl growth during long nights by preferentially binding and stabilizing the active form of phytochrome B (phyB), prolonging its activity. PhyB forms photobodies in the nucleus, where it interacts with molecules of the evening complex (EC) to cause downstream inhibition of hypocotyl growth.

The discovery and characterization of PCH1 is especially notable. PhyB is normally active only during the day. By stabilizing phyB and maintaining its signaling well into the night, PCH1 allows plant cells to “remember” past illumination and adjust growth programs accordingly.

Selected Publications

 * FKF1 and GIGANTEA Complex Formation is Required for Day-Length Measurement in Arabidopsis (2007)


 * ELF4-ELF3-LUX Complex Links the Circadian Clock to Diurnal Control of Hypocotyl Growth (2011)
 * PCH1 Integrates Circadian and Light-Signaling Pathways to Control Photoperiod-Responsive Growth in Arabidopsis (2016)