Translational Control of Euglena LHCPII Synthesis

本提案着眼于在Euglena翻译控制水平上对LHCPII合成的调控。目前正在对Euglena LHCPII的基因组和cDNA克隆进行测序，以确定在LHCPII合成过程中发现的多蛋白中间体衍生的蛋白质的身份。测量LHCPII mRNA水平和LHCPII mRNA进入多体的募集，以确定翻译控制是否在翻译开始或之后的水平上起作用。混合释放和阻滞研究正在用于确定所有四种lhcpii是通过多蛋白mRNA的内部起始衍生的程度。这些研究结果将有助于理解光调控LHCPII在丁香中翻译的机制。本提案着眼于单细胞生物绿藻光合蛋白LHCPII合成的光调节。这种藻类显示出这种蛋白质的一种不寻常的调节模式，使得mRNA的合成保持不变，并且光诱导的LHCPII蛋白的增加与mRNA转化为蛋白质的水平增加有关。本提案中概述的研究着眼于实现这种翻译控制的机制，因为在其他光合生物中，LHCPII的光调节在mRNA产生水平上起作用，而不是翻译水平。本研究结果将为高等生物（包括植物和动物）的转化控制机制提供新的见解。

This proposal is looking at the regulation of synthesis of LHCPII at the level of translational control in Euglena. Both genomic and cDNA clones of Euglena LHCPII are being sequenced to determine the identity of the proteins derived from a polyprotein intermediate found during LHCPII synthesis. LHCPII mRNA levels and the recruitment of LHCPII mRNA into polysomes are measured to determine whether translational control operates at the level of initiation of translation or afterwards. Hybrid-release and - arrest studies are being used to determine the extent to which all four preLHCPIIs are derived through internal initiation of the polyprotein mRNA. The results of these studies will aid in understanding the mechanisms of light regulation of LHCPII translation in Euglena. This proposal looks at the light regulation of protein synthesis of the photosynthetic protein LHCPII in the unicellular organism Euglena. This alga shows an unusual pattern of regulation of this protein such that synthesis of the mRNA is held constant and the light-induced increase in LHCPII protein is associated with an increased level of translation of the mRNA to protein. The research outlined in this proposal is looking at the mechanism by which this translational control is achieved since the light regulation of LHCPII in other photosynthetic organisms operates at the level of mRNA production, not translation. The results of this research should provide new insights into the mechanisms of translational control in higher organisms, both plant and animal.