%0 Journal Article
%T Neurospora crassa Light Signal Transduction Is Affected by ROS
%A Tatiana A. Belozerskaya
%A Natalia N. Gessler
%A Elena P. Isakova
%A Yulia I. Deryabina
%J Journal of Signal Transduction
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/791963
%X In the ascomycete fungus Neurospora crassa blue-violet light controls the expression of genes responsible for differentiation of reproductive structures, synthesis of secondary metabolites, and the circadian oscillator activity. A major photoreceptor in Neurospora cells is WCC, a heterodimeric complex formed by the PAS-domain-containing polypeptides WC-1 and WC-2, the products of genes white collar-1 and white collar-2. The photosignal transduction is started by photochemical activity of an excited FAD molecule noncovalently bound by the LOV domain (a specialized variant of the PAS domain). The presence of zinc fingers (the GATA-recognizing sequences) in both WC-1 and WC-2 proteins suggests that they might function as transcription factors. However, a critical analysis of the phototransduction mechanism considers the existence of residual light responses upon absence of WCC or its homologs in fungi. The data presented point at endogenous ROS generated by a photon stimulus as an alternative input to pass on light signals to downstream targets. 1. Introduction The light perception of fungi is a part of the complex sensory system responding also to changes in the concentrations of nutrient substrates, hormones, temperature shifts, mechanical damage, and so forth, which allows the fungus to adapt its vital functions to environmental changes [1¨C3]. Fungi use light as a source of information but not as a source of energy. Light, as all stress agents, increases intracellular concentration of reactive oxygen species (ROS) in fungi [1, 4]. Experimentally detected relationship of developmental processes with the action of factors increasing intracellular ROS concentration indicated that ROS act as signaling molecules regulating physiological responses and developmental processes in fungi [3, 5¨C7]. Considerable recent attention is focused to molecular mechanisms of ROS signal reception and transduction and modification of gene activity in response to stress factors. Absence of biological motility and lack of behavioral responses in fungi led to induction of the synthesis of compounds (especially carotenoids and melanins in the case of light action) that ensure increased resistance to detrimental effects. Another adaptive response is the differentiation of survival structures such as sclerotia and, of course, spores¡ªthe copies of genetic material of the organism, well protected from damaging environmental influences. Neurospora crassa has served as a model organism to study light responses in eukaryotic cells for several decades [2, 8¨C11]. In this organism, various
%U http://www.hindawi.com/journals/jst/2012/791963/