Part:BBa_K3061001
VchR, Channel rhodopsins of Volvox carteri
It is a kind of photochromic proteins that are activated under wavelength of 589nm. Photocurrent can be produced after activation. The codon usage was optimized to Chlamydomonas reinhardtti.
Usage
This part is a mutated channelrhodopsin , changing its photoreceptor wavelength.
Biology
Channelrhodopsins are light-gated ion channels involved in the photoresponses of microalgae. We know that VchR serves as primary phototaxis photoreceptors in Volvox because the photocurrents of VchR in vitro are similar to those recorded in Volvox cells and because the proteins are closely related to their counterparts in Chlamydomonas[1]. Since VchR has a high similarity with ChR2 and its absorption spectrum range is 100 nm (about 580 nm) reddened by ChR2, we expressed the channel rhodopsin VchR in C. reinhardtii in order to broaden its sensitometric spectrum.
Characterization
Protocols
We characterized the effect of expression through measuring movement features of VchR engineered alga. Measuring protocols see Characeriztion of the motility features of Chlamydomonas Reinhardtii. <a href="https://2019.igem.org/wiki/images/3/30/T--DUT_China_B--4_protocols%EF%BC%9AAbsorption_measurement_of_Fluorescence.pdf">Measuring protocols.pdf</a>
Results and Discussion
Under standard protocols of C. reinhardtii movement measuring, the movement data of VchR engineered Chlamydonomas is showed in figure 1. Engineered C. reinhardtii is able to move under light of 590 nm. The moving speed declines with light intensity and move randomly under 32.6 lx with almost none phototaxis pattern. VchR engineered C. reinhardtii can move at 0.1783±0.0072 mm/s under the blue light of 25.4 lx. We can learn that VchR responses in light of 590 nm more weakly than 480 nm.
You can find the differences from the video of wild C. reinhardtii and engineered C. reinhardtii moving at 590 nm light. <a href="https://2019.igem.org/wiki/images/4/41/T--DUT_China_B--video4.mp4">video</a>
References
[1] Kianianmomeni A , Stehfest K , Nematollahi G , et al. Channelrhodopsins of Volvox carteri Are Photochromic Proteins That Are Specifically Expressed in Somatic Cells under Control of Light, Temperature, and the Sex Inducer[J]. Plant Physiology, 2009, 151(1):347-366. </body> </html>
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