Análisis Funcional de Fotoproteínas en Fusarium

Abstract

The ascomycete Fusarium fujikuroi stands out for its capacity to produce a wide array of secondary metabolites. These compounds exhibit a large chemical diversity and very different biological properties, ranging from pernicious to beneficial for human or animals health, in some cases with biotechnological applications. For this reason, the regulation of secondary metabolism is currently an active area of research. The group of the University of Sevilla where this Thesis has been carried out focuses its attention on the study of the production of F. fujikuroi metabolites, such as carotenoids, gibberellins, bikaverins and fusarins. Their syntheses are controlled by different environmental cues, with light and nitrogen among the most relevant ones. In this Thesis we have analyzed the molecular basis of the regulation by light of carotenoid biosynthesis. Carotenoids are terpenoid pigments that provide colors or exert other biological functions in living beings. As relevant examples, in plants they serve as antenna pigments for photosynthesis, and in animals they are used as signaling and vision molecules. Their role in fungi is under discussion, but in some cases they serve as precursor of other relevant compounds and in others they seem to protect against oxidative stress. Carotenoid photoinduction is a well-characterized response in many fungi, such as Neurospora crassa, Phycomyces blakesleeanus or Mucor circinelloides, where it is performed at transcriptional level of the biosynthetic genes. As found in these fungi, light produces in F. fujikuroi a rapid but transient induction of the expression of the structural genes, in this case carRA, carB, and carT. Former studies with another Fusarium species showed that carotenoid photoinduction is particularly effective with blue light and that the action spectrum of the response suggests the mediation of a photoreceptror with a flavin chromophore. Blue-light responses are coordinated in other fungi by LOV-domain flavin proteins of the WC-1 family. Previous studies in |