The mechanisms involved in macromolecular recognition are central to the understanding of gene regulation. This project will examine the nature and relative importance of functional group interactions between proteins (and other selected ligands) and nucleic acids that are responsible for the formation of high- affinity, sequence-specific complexes. The laboratory will prepare a series of modified oligodeoxynucleotides as possible recognition sites for restriction and modification enzymes, a repressor protein (the tryptophan repressor) as well as selected minor groove binding ligands. The modifications have been chosen in order to minimize structural changes in the B-DNA helix, and involve primarily the "deletion" of selected functional groups. These DNA fragments will be prepared by chemical syntheses employing a variety of modified nucleoside derivatives, including those obtained during the initial and ongoing periods of this project. Parallel studies will be directed toward the effects of modified bases upon DNA structure and the implications of such structure modulation upon recognition processes. Specifically, we will continue to use modified base residues to study DNA curvature phenomena. Additionally, with the minor groove modifications proposed for the present project period, one can examine B-form structure as a function of the ability to form the putative minor groove spine of hydration. By studying recognition phenomena, using site-specifically modified macromolecules, this project should contribute to the understanding of cellular recognition processes and provide access to a variety of useful biochemical tools. %%% There are many examples in nature that involve the selective production of specialized proteins by cells, tissues, and organs which result from the expression of particular genes. This project will examine the nature of functional group interactions between proteins and nucleic acid polymers that are responsible for the formation of high-affinity, sequence-specific complexes involved in gene expression. A series of modified nucleic acid polymers will be prepared to test with proteins which bind to, cut, or chemically modify the related natural polymer. The DNA fragments will be prepared by chemical syntheses employing a variety of modified nucleoside derivatives. Parallel studies will be directed toward the effects of modified bases upon DNA structure and the implications of such structure modulation upon recognition processes. Thus, by studying recognition phenomena, using site- specifically modified macromolecules, this project should contribute to the understanding of cellular recognition processes and provide access to a variety of useful biochemical tools.
