Translational Control of Euglena LHCPII Synthesis

该提案着眼于Euglena在翻译控制水平上对LHCPII合成的调控。眼镜蛇LHCPII的基因组和cDNA克隆正在进行测序，以确定来自LHCPII合成过程中发现的多蛋白中间体的蛋白质的身份。通过测量LHCPII mRNA水平和LHCPII mRNA在多聚体中的募集来确定翻译控制是在翻译开始时还是之后进行。杂交释放和阻断研究正在被用来确定所有四个前LHCPII通过多蛋白mRNA的内部启动而获得的程度。这些研究结果将有助于理解Euglena中LHCPII翻译的光调控机制。这项建议着眼于光对单细胞生物体Euglena中光合蛋白LHCPII的蛋白质合成的调节。这种藻类显示了一种不寻常的调节这种蛋白质的模式，使得mRNA的合成保持不变，光诱导的LHCPII蛋白的增加与mRNA到蛋白质的翻译水平的增加有关。这项提案中概述的研究正在寻找实现这种翻译控制的机制，因为LHCPII在其他光合作用生物中的光调节作用是在mRNA产生的水平上进行的，而不是翻译水平上的。这项研究的结果应该会为高等生物的翻译控制机制提供新的见解，无论是植物还是动物。

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.