Dr. Paul Romaniuk

Research of Dr. Paul J. Romaniuk
PhD McMaster

The research in this laboratory is organised around three main themes involving nucleic acid structure and function. One major focus is on the structure of RNA, and the structure and function of specific RNA-protein complexes. This group has concentrated its efforts on the 5S ribosomal RNA from Xenopus laevis, and the specific complexes this RNA forms with transcription factor TFIIIA, with storage protein p43, and with ribosomal protein L5. The second major focus in the lab concerns the interaction of zinc finger proteins with nucleic acids, and the role of these proteins in transcriptional regulation in eukaryotes. Xenopus TFIIIA not only forms a specific complex with 5S RNA, it also binds specifically to the internal promoter of the eukaryotic 5S RNA gene and activates the expression of this gene. We have been using site-directed mutagenesis techniques to study the molecular basis of this function of TFIIIA, and to compare the DNA and RNA binding activities of this protein. The third major focus in the laboratory concerns the roles of the various isoforms of the Wilms' tumour suppressor protein WT1 in regulating gene expression at the levels of transcription initiation and RNA metabolism. Alternative splicing gives rise to four isoforms of WT1: inclusion of exon 5 can result in a 17 amino acid motif inserted in the N-terminal half of the protein, while use of a second splice donor site at the end of exon 9 can result in the insertion of 3 amino acids (+KTS) between zinc fingers 3 and 4 of the nucleic acid binding domain. We are using a variety of techniques (site-directed mutagenesis, yeast 2 and 3 hybrid assays, SELEX methodologies and proteomics) to study the nucleic acid binding properties of the WT1 isoforms, identify RNA and protein ligands for the WT1 proteins and delineate biological functions of this protein.