Vitamin B12 is an essential enzyme cofactor in humans and other animals. Lack of B12 causes pernicious anemia, neural dysfunction and other disorders. A new molecular function for this vitamin was discovered a few years ago (PNAS, Vol. 108, p 7565-7570, 2011) in a collaboration between Dr. S. Padmanabhan of the NMR group (IQFR) and the Molecular Genetics group of Prof. Montserrat Elías-Arnanz (Universidad of Murcia and Associated Unit to IQFR). It was shown that B12 displays a new role as a light-sensing molecule and that it is involved in light-dependent gene regulation. Now, these researchers in collaboration with others at the University of Manchester (UK), have published a detailed photochemical mechanism for this new class of photoreceptors. The work provides a mechanistic foundation for the emerging field of B12 photobiology and a basis for the development of this class of photoreceptors as optogenetic tools for controlled gene expression in cells and organisms.

Roger J. Kutta, Roger J. Kutta, Samantha J. O. Hardman, Linus O. Johannissen, Bruno Bellina, Hanan L. Messiha, Juan Manuel Ortiz-Guerrero, Montserrat Elías-Arnanz, S. Padmanabhan, Perdita Barran, Nigel S. Scrutton, Alex R. Jones. The photochemical mechanism of a B12-dependent photoreceptor protein. Nature Communications, 6,
Article number 7907, August 12, 2015. doi: 10.1038/ncomms8907.