Blue Light Photoreceptors in Phycomyces

本研究项目的目的是鉴定和分离真菌藻类中作为蓝光感受器的分子。将特别关注向光性突变(基因MADA到MADH)，包括那些光接收器有缺陷的突变(MADB和MADC)(S)。最近的分光光度和生化分析揭示了光感受器突变体的修饰，特别是光诱导的吸光度变化(LIAC)与MADC突变体的特异性变化。LiAc将在体内和体外进行测量，并将作为光感受器的光谱分析(S)。光感受器的生化表征和纯化(S)将采用二维凝胶电泳和快速蛋白质液相色谱(FPLC)，并结合光谱和遗传分析。作为蓝光感受器的可能候选者，黄素蛋白将受到特别的考虑。电泳法和层析法也将应用于在其他行为突变体(MADA、MADB和MAD)中发现的改变的蛋白质。将寻找更多的突变体，并将其纳入该项目。尽管蓝光反应在植物、真菌和其他生物中广泛存在，但感光分子仍有待鉴定。鉴于其无与伦比的敏感性和行为突变体的可用性，Phycomyces提供了特殊的优势。鉴定藻类中的光感受器将极大地促进对与其各种光反应(趋光性、光生长反应、光胡萝卜素合成和光分化)相关的光敏转导的理解。对藻类真菌的研究结果将为其他生物中蓝光感受器的鉴定提供指导。

The objective of this research project is to identify and isolate molecules that serve as blue-light photoreceptors in the fungus Phycomyces. Special attention will be given to phototropism mutants (genes madA to madH) including those (madB and madC) with defective photorecptor(s). Recent spectrophotometric and biochemical analyses have revealed modifications in the photorecptor mutants, notably light-induced absorbance changes (LIAC) with specific alterations in madC mutants. LIAC will be measured in vivo and in vitro and will serve as a spectroscopic assay for the photoreceptor(s). Biochemical characterization and purification of the photoreceptor(s) will employ two-dimensionl gel electrophoresis and fast protein liquid chromatorgraphy (FPLC) in conjunction with spectroscopic and genetic assays. Flavoproteins will receive special consideration as probable candidates for blue light photoreceptors. Electrophoresis and chromatography will also be applied to proteins found to be altered in other behavioral mutants (madA, madB, and madE). Additional mutants will be sought and incorporated in the project. Although blue-light responses are widespread among plants, funji, and other organisms, the photoreceptor molecules remain to be identified. Phycomyces offers special advantages, in view of its unmatched sensitivity and the availability of behavioral mutants. Identification of photoreceptors in Phycomyces will greatly promote the understanding of photosensory transduction in connection with its various light responses (phototropism, light- growth response, photocarotenogenesis, and photodifferentiation). The results on Phycomyces should lead the way to identification of blue light photoreceptors in other organisms.