JAMES T. ANDERSON
Associate Professor

B.Sc. 1990, Southwest Missouri State University, Springfield, MO
Ph.D. 1994, University of Florida, Gainesville, FL
Postdoctoral Fellow: 1995-2000, National Institutes of Health, Bethesda, MD

WLS 412
(414) 288-1481
email: james.anderson@marquette.edu

Click on the Lab Webpage for more information about Dr. Anderson's research program, coursework, and a complete list of publications.

Genetics and Biochemistry of RNA modifying enzymes

The lab is studying mechanisms of RNA nucleotide modification, and the roles modified nucleotides play in RNA function. Transfer RNA (tRNA) contains the greatest number and diversity of modified nucleotides. Interestingly, the function of most tRNA modifications has remained elusive due to the finding that many are not essential for tRNA function. Our current focus is characterizing the essential two-subunit tRNA modification enzyme required for (m1A58) methylation of tRNA in Saccharomyces cerevisiae using both genetic and biochemical approaches. Presently, there are three main projects in the lab.

1. Structure/function of the yeast (m1A) methyltransferase is being probed using genetics to determine regions in the enzyme that are important for overall structure and substrate binding. The m1A Mtase is composed of two non-identical subunits (Trm6p and Trm61p). We are working to understand the significance of the two-subunit structure versus one subunit in most tRNA Mtases, and thus are carrying out experiments to determine the 3-dimensional structure in addition to functional studies underway.

2. We have isolated genetic suppressors that overcome defective m1A Mtase and restore tRNAiMet stability. The suppressor mutations block normal function of the nuclear exosome and a polyA polymerase, Trf4p. We have determined that tRNAiMet lacking m1A58 is 3’ polyadenylation and degraded by 3’-5’ exonucleases found in the exosome. This tRNA surveillance pathway is being explored further to identify additional components of the pathway and to reveal detailed information regarding the mechanism of tRNA recognition and degradation.

3. We have recently begun a new genetic screen to identify genes that are required for growth in the presence of a defective m¹A Mtase enzyme. We have several candidate genes that we are validating using genetics, and initial experiments are being conducted to determine whether these genes are required for the normal processing and/or stability of tRNA_i^Met.

The laboratory provides a great opportunity to individuals looking for research experience in the biochemistry and genetics of tRNA processing.

Selected references:

Kadaba, S., Wang, X. and Anderson J.T. 2006.  Nuclear RNA surveillance in Saccharomyces cerevisiae: Trf4p-dependent polyadenylation of nascent hypomethylated tRNA and an aberrant form of 5S rRNA. RNA March 12(3). 508-521.

Ozanick, S., A. Krecic, J. Andersland and J.T. Anderson. 2005.  The bipartite structure of the tRNA m1A58 methyltransferase from S. cerevisiae is conserved in humans. RNA. Aug;11(8):1281-90.

Kadaba, S., Krueger, A., Trice, T., Krecic, A. M., Hinnebusch, A. G., Anderson, J. 2004. Nuclear surveillance and degradation of hypomodified initiator tRNAMet in S. cerevisiae. Genes Dev. 18 (11) 1227-1240.

Anderson, J., Phan, L., Hinnebusch, A.G. 2000. The Gcd10p/Gcd14p complex is the essential tow-subunit tRNA(1-methyladenosine) methyltransferase of Saccharomyces cerevisiae. PNAS. 97:5173-5178.

Anderson, J., Phan, L., Cuesta, R., Carlson, B.A., Asano, K., Pak, M., Björk, G.R., Tamame, M. Hinnebusch, A.G. 1998. The Essential Gcd10p-Gcd14-p Nuclear Complex is Required for 1-methyladenosine Modification and Maturation of Initiator Methionyl-tRNA. Genes Dev. 12:3650-3662.

Calvo, O., Cuesta, R., Anderson, J., Garcia Barrio, M., Hinnebusch, A.G., Tamame, M. 1999. Gcd14p, a Repressor of GCN4 Translation, Cooperates with Gcd10p and Lhp1p in the Maturation of Methionyl-tRNA in Saccharomyces cerevisiae. Mol. Cell Biol. 19:4167-4181.