VIVID is a flavoprotein and serves as a fungal blue light photoreceptor for photoadaptation

Abstract

Blue light regulates many physiological and developmental processes in fungi. Most of the blue light responses in the ascomycete Neurospora crassa are dependent on the two blue light regulatory proteins White Collar (WC)-1 and -2. WC-1 has recently been shown to be the ®rst fungal blue light photoreceptor. In the present study, we characterize the Neurospora protein VIVID. VIVID shows a partial sequence similarity with plant blue light photoreceptors. In addition, we found that VIVID non-covalently binds ā avin chromophore. Upon illumination with blue light, VIVID undergoes a photocycle indicative of the formation of a¯avin-cysteinyl adduct. VVD is localized in the cytoplasm and is only present after light induction. A loss-of-function vvd mutant was insensitive to increases in light intensities. Furthermore, mutational analysis of the photoactive cysteine indicated that the formation of a¯avin-cysteinyl adduct is essential for VIVID functions in vivo. Our results show that VIVID is a second fungal blue light photoreceptor which enables Neurospora to perceive and respond to daily changes in light intensity.

Trichoderma: sensing the environment for survival and dispersal

“…A second blue light photoreceptor (ENVOY), the orthologue of the N. crassa VIVID (Heintzen et al, 2001;Schwerdtfeger & Linden, 2003), was first identified in T. reesei (Schmoll et al, 2004). ENVOY, a small protein that contains a single PAS/LOV domain, is also encoded in the genomes of T. atroviride and T. virens.…”

Reproduction without sex: conidiation in the filamentous fungus Trichoderma

“…Following a dose of light, WC-1 becomes hyperphosphorylated, and this transient phosphorylation is essential for induction of rapid blue-light-inducible genes (Schwerdtfeger & Linden, 2003). In dark-grown cells and light-adapted cells, protein kinase C (PKC) is thought to phosphorylate WC-1, thus modulating its activity .…”

Enhanced responsiveness and sensitivity to blue light by blr-2 overexpression in Trichoderma atroviride

“…However, the expression pattern of light-regulated genes was the same in the WT and OEblr2-13 strains, indicating that different adaptation mechanisms may be operating. In N. crassa, a negative feedback loop involving the flavoprotein VIVID and phosphorylation by different kinases that destabilize WC-1, and block the transcriptional activity of the WC complex, are the main mechanisms that control adaptation under continuous exposure to light (Schwerdtfeger & Linden, 2003;He & Liu, 2005). T. reesei, a close relative of T. atroviride, has a homologue (ENVOY) of VIVID that might play a similar role in photoadaptation (Schmoll et al, 2005).…”

“…A group of early light-induced genes showing transient expression patterns, typical of adaptive responses, have been identified (Lewis et al, 2002). Among these genes, one encodes a second blue-light photoreceptor, VIVID, necessary for adaptation to constant illumination and to detect changes in light intensity (Schwerdtfeger & Linden, 2003). Although other photoreceptors have been found in the N. crassa genome, it has not been possible to assign any function to them.…”