Design and synthesis of nuclear localization sequence peptidomimetics utilizing glycoside scaffolding

Abstract

In the last decade a considerable amount of research has been applied to the area of nuclear protein import in terms of understanding the import process, that is the study of the process by which proteins are transported from the cytoplasm of a cell to its nucleus. The foundation laid by the biochemical community has provided an excellent opportunity to study various pads of this process from a synthetic organic chemistry perspective, in which synthetic molecules may be used to ascertain issues of molecular recognition in the import process. One principal question left unanswered in the 'classical' nuclear import process is the mechanism by which the cytologic protein, imported α, binds the nuclear localization signal (NLS) of the import protein. The NLS of the import protein consists of a short chain of amino acids that contain several basic residues (lysines and arginines). Thus, it has been proposed, and very recently illustrated through X-ray crystallographic analysis that the binding site of importer α, has at affinity for the positive charges produced by the basic residues in the NLS. Therefore, my objective was to synthesize NLS mimics by suspending propylamine sidechairs (lysine mimics) from various pyranose carbohydrate scaffolds. Once synthesized these tetra-aminopropyl glycosides were then tested in a competition assay with a fluorescently tagged import active reporter protein- NLS conjugate. The second objective was to incorporate a functional handle on those tetra- aminopropyl glycosides that exhibited the most effective inhibition in the competition assay. The functional handle would serve as a linker for conjugating the tetra-aminopropyl glycosides to a non-import active protein. In this way it would be possible to determine conclusively whether those glycosides had the required property, molecular recognition by importer a, and would then be capable of directing active import of a protein.