Functions of the Acidic Ribosomal Proteins of Maize

蛋白质合成是一个多步骤的过程，在玉米和所有其他生物中受到多个水平的调节。幼苗根系的缺氧（低氧）胁迫反应包括快速抑制起始，随后选择性起始和mRNA翻译的延长。低氧胁迫反应为研究低能条件下蛋白质合成的调控提供了模型。本项目主要研究酸性核糖体蛋白（ARPs）在缺氧条件下的修饰。三种酸磷酸化蛋白，称为P0， P1和P2，以多聚体结构存在于核糖体的活性位点，在翻译的起始后期，延伸和终止阶段，mRNA， tRNA和翻译因子之间发生相互作用。生化目的是鉴定玉米的P0、P1和P2，分析好氧根和缺氧根的单核糖体和多核糖体中三种ARPs的化学计量学特征，表征控制和缺氧条件下ARPs的体内磷酸化，并分析ARPs在缺氧条件下的其他修饰。分子目标是鉴定和测序编码玉米ARPs的基因，并启动ARPs基因磷酸化位点的定点诱变。长期目标是测试ARP修饰在玉米根尖离体翻译系统中的作用。这些实验将为阐明高等植物蛋白质合成机制中核糖体的结构-功能关系提供基础。该项目涉及与墨西哥城墨西哥国立自治大学的Estela Sanchez de Jimenez博士合作。＊＊＊

9315015 Bailey-Serres Protein synthesis is a multi-step process that is regulated at numerous levels in maize as well as in all other organisms. The hypoxic (low-oxygen) stress response of seedling roots involves the rapid inhibition of initiation, followed by selective initiation and elongation of mRNA translation. The hypoxic stress response provides a model for studying modulation of protein synthesis under low energy conditions. This project focuses on modifications of acidic ribosomal proteins (ARPs) in response to hypoxia. Three acidic-phosphorylated proteins, known as P0, P1 and P2, are present as a multimeric structure in the active site of the ribosome where interactions between mRNA, tRNA and translation factors occur during the late-initiation, elongation and termination phases of translation. The biochemical objectives are to identify P0, P1 and P2 of maize, analyze the stoichiometry of the three-types of ARPs in monoribosomes and polyribosomes of aerobic and hypoxic roots, characterize the in vivo phosphorylation of ARPs under control and hypoxic conditions, and analyze other modifications of ARPs in response to hypoxia. The molecular objectives are to identify and sequence the genes encoding the ARPs of maize, and to initiate site-directed mutagenesis of the phosphorylation sites of the ARPs genes. The long-term goal is to test the role of ARP modification in an in vitro translation system from maize root tips. These experiments will provide the foundation for the elucidation of ribosome structure-function relationships in mechanisms of protein synthesis in higher plants. This project involves a collaboration with Dr. Estela Sanchez de Jimenez at National Autonomous University of Mexico, Mexico City. ***