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

Channelrhodopsins are light-gated ion channels involved in the photoresponses of microalgae. We know that VChRs serve 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 the sensitometric spectrum of Chlamydomonas reinhardtii.

Biology

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.

Characterization

1 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. Measuring protocols.pdf

2 Results and discussion

Under standard protocols of alga movement measuring, the movement data of VchR-engineered Chlamydonomas is showed in figure 1. As we can see from the figure, VchR-engineered Chlamydonomas is able to move under light of 590 nm.The moving speed of alga declines with light intensity, until showing random movement pattern at 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.

Figure 1 Speed of VchR-engineered C. reinhardtii under 590 nm,orange light

You can find the differences from the video of wild C. reinhardtii and engineered C. reinhardtii moving at 590 nm light. video

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.

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