Genetic and Biochemical Studies of the Tryptophan Operon

一个主要的努力将是了解trp阻遏子与该阻遏子控制的三个操作子的相互作用和调控的分子细节。结构-功能研究将使用突变阻遏物进行。这些研究应阐明色氨酸结合位点的结构要求、二聚体的形成过程和异源二聚体的性质、氨基端臂的作用以及螺旋E的氨基酸序列、阻遏物的dna识别序列和三种操作符中识别的碱基对之间的关系。此外，还将对不同类型的突变体进行第二位点逆转研究，以分析阻遏物内部的补偿相互作用和阻遏物不同区域的功能改变。生理学研究将继续努力，以更好地了解trp基因调控如何在生长细胞中发生。对色氨酸合成酶进化的研究将继续进行，并将重点关注酵母和神经孢子菌从细菌的单独多肽进化为单个色氨酸合成酶多肽时发生的基因重排和基因融合。

A major effort will be made to understand the molecular details of trp repressor interaction with, and regulation of, the operators of the three operons this repressor controls. Structure-function studies will be performed using mutant repressors. These studies should elucidate the structural requirements of the tryptophan binding site, the process of dimer formation and the properties of heterodimers, the role of the amino terminal arm, and the relationship between the amino acid sequence of helix E, the DNA-recognition sequence of the repressor, and recognized base pairs in the three operators. In addition, second site reversion studies will be carried out with various mutant classes to analyze compensating interactions within the repressor and functional alterations in different regions of the repressor. Physiological studies will be continued in an effort to better understand how trp gene regulation occurs in growing cells. Studies on the evolution of tryptophan synthetase will continue and will focus on the gene rearrangement and gene fusion that occurred in the evolution of the single tryptophan synthetase polypeptide of yeast and Neurospora from the separate polypeptides of bacteria.