Cobalamin Binding Domains

Photogenetic methods accurately control molecular processes, cellular signals and animal behavior in space and time by using microbial or plant photoreceptor domains that can interact between molecules or within molecules under light control. Most of the currently available domain libraries allow the formation of protein complexes induced by blue or red light. However, the photoreceptor domains currently used do not respond most to green light, which constitutes a notorious "blind spot" in photogenetics experiments.

With the in-depth research in the field of optogenetics, it is found that cobalamin (vitamin B12) binding domain (CBD) can be used to mediate the receptor interaction that can be eliminated by green light in the dark, and these domains can be used to regulate the signal pathway and cell development in human cells.

CBD from Myxococcus xanthus (MxCBD) and CBD from Thermus thermophilus (TtCBD) are commonly used photoreceptor. Creative BioMart provides plenty of services and related solutions based on the MxCBD and TtCBD switch systems.

Basic Parameters and Characteristics

	MxCBD	TtCBD
Photoreceptor	MxCBD	TtCBD
Binding partner	/	/
Cofactor	AdoCbl, MetCbl or CNCbl	AdoCbl, MetCbl or CNCbl
Source organism	Myxococcus xanthus	Hermus thermophilus
Mode of action	Heterodimerization, dissociation	Heterodimerization, dissociation
Excitation wavelength	545 nm	545 nm
Reversion wavelength	Dark	Dark

MxCBD Switch System

In recent years, the CBD of CarH of Myxococcus flavus and thermophilic bacteria and the related functions of Streptomyces coeruleus and Bacillus megaterium have emerged. Relatively small CBDs mediate the assembly of dimers in the dark. These molecules decompose into monomers under green light after photolysis of 5'-deoxyadenocobalamin (AdoCbl) cofactor. AdoCbl is an active form of cobalamin and is also synthesized in the mitochondria of eukaryotic cells. In mammals, cobalamin is necessary for erythrocyte formation, neural function and protein and DNA synthesis. Excessive intake of cobalamin in healthy individuals will not produce any side effects.

TtCBD Switch System

Hermus thermophilus control gene expression in mammalian cells. The system plays a role in various mammalian cell lines, showing high induction (up to 350 fold), low leakage and high reversibility. The protein CarH from the TtCBD switch carries the cofactor adob12 to sense green light, form tetramers in the dark and decompose into monomers under green light.