Signal Transduction Mechanisms Controlling Chromatic Adaptation

这项研究探讨了控制细菌光反应的信号转导机制。它试图揭示蓝藻Fremyella双虹吸是如何感知和响应光线颜色的变化的。这一过程被称为“互补染色适应”(CCA)，涉及这种光合作用有机体的捕光触角的大规模重新合成，导致完全的颜色变化。这种可逆的驯化过程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。CCA由两条光反应通路控制，这两条通路介导了许多基因转录的变化。RCA途径似乎是一个复杂的磷继电器，控制红光和绿光诱导基因的表达，包含三个已知成分，一个光敏色素样光感受器和两个反应调节因子。CGI途径只控制绿光诱导的基因。这条途径中的任何成分都没有被分离出来。RCA和CGI系统可能通过一种类似OmpR的控制机制整合在DNA序列上，称为“R盒”。这些研究将回答有关CCA调节机制的基本问题。他们将通过缺失和连接子扫描分析、蛋白质结合和足迹研究以及CCA转录因子的纯化来确定(I)红光如何增加pcyA和cpc2的表达水平；(Ii)CGI和RCA系统如何通过启动子和R盒缺失分析来调节cpeCDESTR的表达；以及(Iii)通过转座子突变和对可能的CGI突变体的分析，哪些成分组成了CGI系统。更广泛的影响包括增加对光合作用物种如何适应光的理解，以及对科学中代表性不足群体的成员进行培训。

This research investigates signal transduction mechanisms controlling light responses in bacteria. It seeks to uncover how the cyanobacterium Fremyella diplosiphon senses and responds to changes in light color. This process, called "complementary chromatic adaptation" (CCA), involves massive resynthesis of this photosynthetic organism's light harvesting antennae, resulting in a complete color change. This reversible acclimation process allows cells to efficiently use the predominant light wavelength(s) in the environment for photosynthesis. CCA is controlled by two light-responsive pathways that mediate changes in transcription of many genes. The Rca pathway appears to be a complex phosphorelay that controls the expression of red and green light-induced genes and contains three known components, a phytochrome-like photoreceptor and two response regulators. The Cgi pathway controls only green light induced genes. None of the components in this pathway have been isolated. The Rca and Cgi systems may integrate at DNA sequences called "R Boxes" through an OmpR-like control mechanism. These studies will answer fundamental questions concerning the mechanism of CCA regulation. They will determine (i) how red light increases pcyA and cpc2 expression levels through deletion and linker scanning analyses, protein binding and footprinting studies, and purification of CCA transcription factors (ii) how the Cgi and Rca systems regulate cpeCDESTR expression through promoter and R Box deletion analysis and (iii) what components make up the Cgi system by transposon mutagenesis and analysis of putative cgi mutants. Broader impacts include increased understanding of how photosynthetic species acclimate to light and training of members of underrepresented groups in science.