PHYCOBILIN GENE STRUCTURE AND REGULATION

藻胆素是藻胆素的主要辅助光合色素。 蓝藻。它们存在于称为藻胆体的结构中 它们位于类囊体膜的表面，可以 占细胞蛋白质的50%以上。藻胆素也是一种 在这些生物体中有大量的氨基氮储备， 蛋白质在氮饥饿期间被降解。这是 在固氮蓝藻中尤其重要，因为它 支持固氮酶和其他所需蛋白质的合成 用于固氮和异形胞发育。我们的长期计划 藻胆素研究的目标是鉴定和表征 藻胆蛋白及其相关蛋白的基因组成 藻胆体和了解这些基因是如何在 固氮蓝藻与氮代谢的关系。 这项工作是我们更广泛基础研究的一部分 氮代谢的分子生物学研究进展 蓝藻。这里提出的研究的具体目标是 鉴定和鉴定主要藻胆蛋白的基因 变色鱼腥藻29413的生物学特性及其调控研究 与氮代谢的不同状态的关系，尤其是 氮气饥饿。我们将从我们的CH30中分离出基因- 含异源探针和/或人工合成的鱼腥藻文库 寡核苷酸。这些基因将被测序，他们的基因 基因组中的组织将被确定。我们将使用 杂交技术、脉冲标记和光谱学 分析研究藻胆蛋白基因标记的调控，以及 光谱分析研究藻胆蛋白基因的调控 表情。几种不同的氮源，以及氮气 饥饿，将检测它们对mRNA和 蛋白质水平。

Phycobilins are the major accessory photosynthetic pigments of cyanobacteria. They are found in structures call phycobilisomes which lie on the surface of the thylakoid membranes and may comprise over 50% of the cell protein. Phycobilins also serve as a large reserve of amino nitrogen in these organisms, and the proteins are degraded during nitrogen starvation. This is particularly important in nitrogen-fixing cyanobacteria, since it supports synthesis of nitrogenase and the other proteins needed for nitrogen fixation and heterocyst development. Our long term goals for research on phycobilins are to identify and characterize the genes for phycobilins and related proteins which constitute phycobilisomes and to understand how the genes are regulated in relation to nitrogen metabolism in nitrogen-fixing cyanobacteria. This work is one part of more broadly based studies we are conducting on the molecular biology of nitrogen metabolism in cyanobacteria. The specific aims of the studies proposed here are to identify and characterize the genes for the major phycobilins of Anabaena variabilis 29413 and to study their regulation in relation to different states of nitrogen metabolism, especially nitrogen starvation. We will isolate genes from our Ch30- Anabaena library with heterologous probes and/or with synthetic oligonucleotides. The genes will be sequenced, and their organization in the genome will be determined. We will use hybridization techniques, pulse labeling, and spectroscopic analysis to study regulation of phycobilin gene labeling, and spectroscopic analysis to study regulation of phycobilin gene expression. Several different nitrogen sources, as well as nitrogen starvation, will be examined for their effect on mRNA and protein levels.