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，生物化学和遗传学的方法，它分析了蓝藻Fremyella diplosiphon如何利用色适应来响应环境光颜色的变化。在色彩适应过程中，这种光合生物的捕光触角被重组。这种适应过程是可逆的，并允许细胞有效地利用环境中的主要光波长进行光合作用。色适应控制红色和绿色光响应基因的转录。最近，在红光和绿色光响应基因附近发现了称为“R盒”的28个碱基对的DNA区域，表明该序列是协调红光和绿色光表达所必需的。这项研究将测试R盒在光响应基因调控中的作用。色适应是由两个感光系统控制的。Rca（调节色适应）系统似乎是控制红光和绿色光响应基因的表达的复杂的磷酸化继电器，并且包括称为RcaC的大的响应调节器。在红光和绿色光下生长的细胞中，RcaC的丰度是不同的。这项研究将确定RcaC的丰度是否受到转录、转录或蛋白水解的调控。第二个调节系统，Cgi（绿色光诱导的控制）系统，调节绿色光诱导的基因并且是未表征的。本项目将利用转座子诱变产生潜在的Cgi系统突变体，并鉴定编码该途径组分的基因。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.