Mechanism of Protein Import into Peroxisomes

We have described two different signals (PTS1 and PTS2) that can translocate proteins into the peroxisome matrix. PTS1 is a C -terminal tripeptide found in about 40 peroxisomal proteins, while PTS2 is N-terminal and used by a smaller set of proteins. Human patients with Zellweger syndrome transport proteins containing PTS2 but not those with PTS1 into peroxisomes. We have established systems to study protein import into peroxisomes of semi-intact cells. We have also isolated many peroxisome assembly /import mutants in the yeast Pichia pastoris . Current work is focused on the elucidation of the mechanism of peroxisomal import and the cloning and characterization of genes involved in peroxisome assembly/import.

DNA Repair and Recombination

We have cloned and characterized several genes in S. pombe that are involved in molecular checkpoint functions that ensure the orderly progression of events in the cell cycle. The pathways by which these genes mediate cell cycle control is one of our goals. We are also characterizing mutants and genes involved in mitotic recombination in S. pombe.