Research Laboratories
PLANT ENVIRONMENTAL RESPONSES (Takeshi Kanegae, Rei Narikawa)
Research Overview
Growth and development in plants are strongly regulated by light from the environment. We are currently investigating two crucial processes - plant photo morphogenesis and intracellular chloroplast phototaxis by looking at the mechanisms behind light detection, and signal transduction, and changes in expression. Using model organisms such as the moss Physcomitrella patens, the fern Adiantum capillus-veneris, and the flowering plant Arabidopsis thaliana, we analyze these mechanisms at the cellular, physiological, and molecular levels.
The Narikawa group's research focuses on photosynthetic cyanobacteria, with the objective of elucidating light utilization strategies in these microorganisms from the molecular to the cell population level. Photosynthetic organisms utilize light as a source of energy. However, they also perceive it as an essential environmental cue, and have thus evolved sophisticated light response mechanisms. By looking at how photosynthetic organisms respond to light, we are aiming to shed light into the mechanisms that govern these responses. Additionally, we are also working to develop molecular modifications of identified light-responsive proteins for applications in optogenetics and fluorescence imaging.
Our current research themes include the following:
- Photomorphogenesis (Kanegae Group)
- Chloroplast Phototaxis (Kanegae Group)
- Understanding light response strategies in cyanobacteria (Narikawa Group)
- Application of cyanobacteriochromes (Narikawa Group)
If you are interested in joining the graduate program and doing research with us, please contact us through email.
Current Projects
(1) Photomorphogenesis (Kanegae Group)
Plants spend their entire lives as sessile organisms, meaning they are unable to move freely and must continuously monitor and adapt to changes in their environment to be able to maximize their growth. One example of this can be seen in bean sprouts - when grown in the dark, they appear elongated and their leaves do not develop. When they are exposed to sunlight however, they develop normal cotyledons and gradually transition to the growth pattern of typical seedlings. This light-induced change in plant morphology is what we know as photomorphogenesis.
In order for plants to sense light, they require pigment-based photoreceptors. Previously identified receptors include phytochromes (red and far-red light), cryptochromes, and phototropins (blue light). Our research in this area looks at photomorphogenesis of ferns and mosses at a cellular level. We examine how these photoreceptors detect light and how the cytoskeleton facilitates the subsequent changes in morphology.
(2) Chloroplast Phototaxis (Kanegae Group)
One other interesting characteristic of the phototropin and phytochrome photoreceptors is their involvement in the intracellular movement of chloroplasts. As essential organelles for photosynthesis, chloroplasts must actively reposition themselves within plant cells based on the abundance of light in order to optimize light exposure. When light is scarce, chloroplasts move to areas in the cell which receive the most amount of light (low-light response, accumulation response). Conversely, when light is plenty, they distribute and relocate to avoid excessive exposure in order to prevent chlorophyll bleaching (high-light response, avoidance response). Although this process happens without changes in morphology, it is a another demonstration of environmental perception and adaptation in plants. The work we do in this aspect focuses on understanding the molecular mechanisms underlying light-responsive relocation (phototaxis), from photoreceptor light sensing to the cytoskeleton-dependent movement of the chloroplasts.
(3) Understanding light response strategies in cyanobacteria (Narikawa Group)
Cyanobacteriochromes are photoreceptors that occur abundantly in cyanobacteria. From our past research, we have identified and analyzed many different cyanobacteriochromes that exhibit unique spectroscopic properties. Building on these findings, we continue to investigate these photoreceptors and continue to dig deeper into their roles. We have also done previous work on cyanobacteriochrome structural and spectral tuning properties. To expand this further, we are conducting sequence comparison as well as physiological and ecological studies to uncover novel cyanobacteriochromes. Moreover, we are involved in characterizing the biochemical and spectroscopic properties of cyanobacteriochromes in lesser-studied species in order to improve our understanding of the physiological and genetic functions in these species.
(4) Application of cyanobacteriochromes (Narikawa Group)
The cyanobacteriochromes we have so far studied possess a pigment-binding GAF domain. They also reversibly convert between two-light absorbing with high stability. In addition, they also emit fluorescence despite a low quantum yield. These properties make cyanobacteriochromes valuable for developing optogenetic light switches which can allow for the posibility of controlling cellular processes, as well as for fluorescent probes in molecular imaging in cells. At present, we are working on identifying novel GAF domains and introducing mutations to known GAD domains in order to create high-functioning variants. Our goal is to discover and engineer GAF domains to enhance their performance in optogenetic and fluorescence imaging applications.
Staff Highlight
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Dr. Takeshi Kanegae (鐘ヶ江健) Associate Professor | Dr. Rei Narikawa (成川礼) Associate Professor |
Email: | |
tkanegae[at]tmu.ac.jp | narikawa.rei[at]tmu.ac.jp |
| Read more: | |
Lab Information: | |
Recent Publications
1. Engineering of Phycourobilin Synthase: PubS to a Two-Electron Reductase
Keita Miyake, Saya Iwata, Rei Narikawa. Plant and Cell Physiology, pcae098, Sep 2024
2. Red/green cyanobacteriochromes acquire isomerization from phycocyanobilin to phycoviolobilin
Hiroki Hoshino, Keita Miyake, Keiji Fushimi, Rei Narikawa. Protein Science, 33(8) e5132, Aug 2024
Mizuho Sato, Takeshi Kawaguchi, Kaisei Maeda, Mai Watanabe, Masahiko Ikeuchi, Rei Narikawa, Satoru Watanabe
ACS Synthetic Biology, 13(8) 2391–2401, Jul 2024
Mana Fukazawa, Keita Miyake, Hiroki Hoshino, Keiji Fushimi, Rei Narikawa. Plant and Cell Physiology, pcae077, Jul 2024
Izumi Kimura, Takeshi Kanegae. Journal of Experimental Botany, 75(8) 2403–2416, April 2024
See more: (ResearchMap (Kanegae)) (Google Scholar (Narikawa))
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