Related Experiment Video
Updated: Jul 20, 2026
07:58
Non-invasive Assay for Chlorophyll Biosynthesis Kinetics Determination during Early Stages of Arabidopsis De-etiolation
Published on: January 12, 2024
Time-resolved detection of conformational changes in oat phytochrome A: time-dependent diffusion
Takeshi Eitoku1, Xristo Zarate, Gennady V Kozhukh
1Department of Chemistry, Graduate School of Science, Kyoto University, Japan.
Biophysical Journal
|August 29, 2006
Summary
Photoexcitation of oat phytochrome A (phy) causes significant conformational changes. The far-red-absorbing form (Pfr) shows reduced diffusion, indicating altered interactions with water molecules within 1 ms.
Area of Science:
- Plant molecular biology
- Photochemistry
- Biophysics
Background:
- Phytochrome A (phy) is a crucial photoreceptor in plants, mediating responses to light.
- Understanding the conformational dynamics of phytochrome is key to elucidating its signaling mechanisms.
Purpose of the Study:
- To investigate the time-resolved conformational changes of oat phytochrome A (phy) in solution after photoexcitation.
- To characterize the structural differences between the red-absorbing (Pr) and far-red-absorbing (Pfr) forms of phy.
Main Methods:
- Utilized the pulsed laser-induced transient grating technique to study phytochrome dynamics.
- Measured diffusion coefficients (D) of different phytochrome forms in solution over time.
Main Results:
- The diffusion coefficient of the Pfr form of large phy was significantly reduced (1.3 x 10(-11) m(2) s(-1)) compared to the Pr form (5.8 x 10(-11) m(2) s(-1)), indicating increased intermolecular interactions.
- Photoexcitation of intact phy's Pr form caused an initial decrease in D within 1 ms, followed by a gradual increase over 100 ms towards the Pfr value.
- The slower conformational change in the N-terminal region of intact phy was linked to alpha-helix formation.
Conclusions:
- Photoexcitation induces rapid global conformational changes in phytochrome, affecting its interaction with water.
- A slower, distinct conformational change occurs in the N-terminal region, potentially involving alpha-helix formation, which modulates these interactions.
Related Concept Videos
01:19Protein Dynamics in Living Cells
Different fluorescence-based techniques are used to study the protein dynamics in living cells. These techniques include FRAP, FRET, and PET.
Fluorescent recovery after photobleaching (FRAP) is a fluorescent-protein-based detection technique used to quantify protein movement rates within the cell. This method exposes a small portion of the cell to an intense laser beam. The laser beam causes permanent photobleaching of the fluorophore-tagged proteins in the exposed region. As the bleached...
Fluorescent recovery after photobleaching (FRAP) is a fluorescent-protein-based detection technique used to quantify protein movement rates within the cell. This method exposes a small portion of the cell to an intense laser beam. The laser beam causes permanent photobleaching of the fluorophore-tagged proteins in the exposed region. As the bleached...
02:45Biological Clocks and Seasonal Responses
The circadian—or biological—clock is an intrinsic, timekeeping, molecular mechanism that allows plants to coordinate physiological activities over 24-hour cycles called circadian rhythms. Photoperiodism is a collective term for the biological responses of plants to variations in the relative lengths of dark and light periods. The period of light-exposure is called the photoperiod.
01:24Protein Diffusion in the Membrane
Proteins show rotational as well as lateral diffusion across the membrane. The lateral diffusion of proteins was confirmed through the cell fusion experiment where mouse and human cells were fused, resulting in hybrid cells. When the human and mouse cells fused, the specific membrane proteins on human and mouse cells were marked with the red and green-fluorescent markers, respectively. Initially, the red and green fluorescence was located on the respective hemisphere of the cell. As time...