Biochemical and Genetic Analysis of Light Regulated Signal Transduction

这项研究探讨了控制细菌光反应的信号机制。利用分子、生化和遗传方法，分析了蓝藻Fremyella diplosiphon如何利用颜色适应来响应环境光颜色的变化。在颜色适应过程中，这种光合作用有机体的捕光触角进行了重组。这种驯化过程是可逆的，使细胞能够有效地利用环境中的主要光波长(S)进行光合作用。颜色适应控制红光和绿光反应基因的转录。最近，在红光和绿光反应基因附近发现了一个DNA的28个碱基对区域，称为“R盒”，这表明该序列是协调红光和绿光表达所必需的。这项研究将测试R盒在光反应基因调控中的作用。已知的颜色适应由两个光感系统控制。RCA系统似乎是一个复杂的磷继电器，它控制红光和绿光反应基因的表达，并包括一个名为RcaC的大型反应调节因子。RcaC丰度在红光和绿光下生长的细胞中是不同的。这项研究将确定RcaC丰度是在转录、翻译还是蛋白质降解方面受到调节。第二个调控系统，CGI(控制绿光诱导)系统，调控绿光诱导基因，但尚未确定。该项目将使用转座子突变来产生潜在的CGI系统突变，并识别编码这一途径的组成部分的基因。这些发现将有助于更广泛地了解细菌信号转导系统和植物信号通路。

This research investigates signaling mechanisms controlling bacterial light responses. Using molecular, biochemical, and genetic approaches, it analyzes how the cyanobacterium Fremyella diplosiphon uses chromatic adaptation to respond to changes in ambient light color. During chromatic adaptation, this photosynthetic organism's light harvesting antennae are restructured. This acclimation process is reversible and allows cells to efficiently use the predominant light wavelength(s) in the environment for photosynthesis. Chromatic adaptation controls transcription of red and green light responsive genes. Recently, a 28 basepair region of DNA called the "R Box" was found near both red and green light responsive genes, suggesting that this sequence is required for coordination of red and green light expression. This research will test the role of the R Box in the regulation of light-responsive genes. Chromatic adaptation is known to be controlled by two photosensory systems. The Rca (regulator for chromatic adaptation) system appears to be a complex phosphorelay that controls the expression of red and green light responsive genes and includes a large response regulator called RcaC. RcaC abundance differs in cells grown in red and green light.This research will determine if RcaC abundance is regulated transcriptionally, translationally, or proteolytically. The second regulatory system, the Cgi (control of green light induction) system, regulates green light induced genes and is uncharacterized. This project will use transposon mutagenesis to generate potential Cgi system mutants and identify genes encoding components of this pathway. These findings will contribute broadly to understanding of bacterial signal transduction systems and plant signaling pathways.