Researchers of the university of Seville identify a gene that allows fungus to react to light

Professor Luis Corrochano Peláez, from the Genetics Department of the University of Seville, and his PhD student Julio Rodríguez Romero, in collaboration with researchers of the Duke University of USA and the University of Salamanca, have identified a gene that allows Phycomyces fungus to react to light and orientate their growth toward it. Results will be published in the prestigious journal “Proceedings of the National Academy of Sciences USA” next week. These researches are part of the scientific activity of the Genetics Department of the University of Seville, which has a long-standing tradition in basic research and research applied to the genetics of microorganisms.

Phycomyces blakesleeanus fungus is used in labs to research into the mechanisms that allow living creatures to relate to their environment. The fruiting body of the Phycomyces is sensitive to several environmental stimulus, such us the light, gravity, wind and the presence of close obstacles that modify the speed and direction of its growth. Like plants, Phycomyces grows in the direction of light, against gravity.

In the 1960’s, Nobel prize-winner Max Delbrück started in his lab, in the California Institute of Technology, to search for night-blind mutants of Phycomyces whose fruiting bodies could not move toward the light. These mutants were called mad in honour to Max Delbrück, whose birth centenary is this year, and were used to research into the mechanisms responsible for sight.

However, the identity of the genes altered in mad mutants was unknown until now. Genetics experts from Seville University, in collaboration with their colleagues from Salamanca and the USA, have succeeded in identifying the altered gene in one of the mad mutants and in describing their product.

The product of madA gene is a protein that can be linked to DNA and a compound, flavin, which absorbs blue light and allows it to act as a photoreceptor and activator of genes at the same time. There are similar proteins in other type of fungus, although Phycomyces contains two genes of this type. This could explain its great sensibility to light, similar to that of the human eye. These proteins share with a group of proteins of plants, the phototropins, the union spot of the compound that absorbs the light. This means that fungus and plants can use a similar mechanism to grow toward the light.

The identification of the nature of madA gene puts an end to a story that began in Delbrück’s lab about forty years ago and will be used to understand better the mechanisms that regulate the responses of microbes to environmental changes. The completed Phycomyces genome sequence, which is expected to be known next year, will be very useful to reach these objectives.