Research Fellow

EDUCATION AND POSITIONS HELD:

• Ph. D. Biochemistry, University of Montana, USA (1981).
• Visiting Assistant Professor, University of Montana, USA (1981-1982)
• Postdoctoral Fellow, Institute of Enzyme Research, University of Wisconsin, Madison, Wisconsin, USA (1982-1984)
• Scientist, Pharmacia/LKB, USA (1984-1986)
• Associate Research Fellow, Institute of Molecular Biology, Academia Sinica, ROC (1986-1990)
• Visiting Professor, Department of Biological Sciences, Carnegie Mellon University, USA (2002)
• Research Fellow, Institute of Molecular Biology, Academia Sinica, ROC (1990-present)

RESEARCH INTERESTS:

The main interest of our laboratory is on proteins with arginine side chain methylation and the subsequent cellular responses. There are at least three types of protein arginine methyltransferases (PRMTs). The type I enzymes mediate the formation of ω-N^G-monomethylarginine (ωMMA) and asymmetric ω-N^G-N^G-dimethylarginine (aDMA). The type II enzymes have the symmetric ω-N^G-N^G'-dimethylarginine (sDMA) in addition to the ωMMA as products. The δ-guanidino nitrogen of the arginine side chain can also be methylated with a type IV PRMT from the yeast. Asymmetrical dimethylation of arginines has been shown to influence mRNA nuclear export, protein-protein interactions and transcription. Symmetrical dimethylarginine methylation is required for the localization of SMN (survival of motor neurons) in Cajal bodies and pre-mRNA splicing. Proteins with monomethyl arginine have been observed in tumor cells during apoptosis. The cellular functions of proteins with monomethylarginine are at present unknown.
Our laboratory is using yeast as a model system to study the cellular responses to protein arginine methylation. We have identified Sbp1p as a substrate of Hmt1p which is a type I PRMT. Sbp1p is a nucleolar single-strand nucleic acid binding protein that we found associated with the ribosome. Sbp1p interacts with numerous proteins but only the methylated Sbp1p can bind Nop13p, Mas1p and Rpl16Ap. The results implicate the involvement of methylated Sbp1p in rRNA processing.
Ribosomal protein Rpl12p is δ-monomethylated at Arg67 by RMT2. Yeast strain with RPL12A and RPL12B double deletion exhibits slow growth and slow translation. Cells transformed with plasmids encoding the wild type Rpl12p or its Arg67 to lysine mutant have different growth rate. We are testing whether mRNAs are preferentially translated on the polysomes of these strains.