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Deborah E. Lycan |
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B.A. University of California, San Diego |
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S
. cerevisiaeCurrent
Teaching
Bio
200 Investigations
in Cell and Molecular Biology
Bio
311 Molecular Biology
Bio 312
Recombinant DNA Lab
BCMB 410 Biochemistry/Molecular
Biology Seminar
Bio 320 Human Genes and Disease
Current research interests and projects
We are interested in the assembly and export of ribosomal subunits from the nucleii of eukaryotic cells. This complex and highly conserved process involves over 170 non-ribosomal proteins in the yeast, S. cerevisiae. Ribosome assembly takes place mostly in the nucleolus, and is a co-transcriptional process. Three of the core rRNAs are transcribed from tandemly repeated rDNA copies in the nucleolus into a 35S pre-rRNA. Many of the accessory factors required for ribosome biogenesis are involved in the processing and modification of the large 35S precurosr rRNA.
In yeast, the large and small ribosomal subunits are exported independently of one other, in a process that requires both Crm1 (exportin 1) and RanGTP. Our lab has focussed our research efforts on the 40S subunit, investigating what proteins are required for late steps in assembly or nuclear export. We have identified two stress-responsive genes that encode proteins required for efficient 40S biogenesis, YAR1 and LTV1. Strains lacking either YAR1 or LTV1 produce about half the normal number of 40S subunits, accumulate free 60S subunits, and exhibit a slow growth phenotype . Yar1 interacts with both Ltv1 and RpS3, a late assembling small subunit protein, in a two hybrid screen, and interacts directly with RpS3 in vitro. Over-expression of RpS3 in cells lacking Yar1 can rescue the ?yar1 phenotype, but does not rescue the ?ltv1 phenotype in cells lacking Ltv1. We recently published a number of experiments whose results are consistent with the hypothesis that Ltv1 may function as an export adapter for the small subunit. Work ongoing in the lab is designed to further investigate the role of these two proteins in the production and export of functional 40S ribosomal subunits.
Selected publications:
Deborah Lycan, Glen Mikesell, Maureen Bunger*
and Linda Breeden. (1994) Differential effects of Cdc68 on cell cycle-regulated
promoters in Saccharomyces cerevisiae. Mol. Cell. Biol. 14:7455-7465.
Deborah Lycan, Kimberlee Stafford*, William Bollinger* and Linda Breeden. (1996) A new Saccharomyces cerevisiae ankyrin repeat-encoding gene required for a normal rate of cell proliferation. Gene 171:33-40.
Sandra P. Ewaskow, Julia M. Sidarova, Deborah Lycan, J. Craig Emery* Jorg Hendle, Kam Y.J. Zhang and Linda L. Breeden. (1998) Mutation and Modeling Analysis of the Saccharomyces cerevisiae Swi6 Ankyrin Repeats. Biochemistry 37:4437-4450.
Jesse W. Loar*, Robert M. Seiser, Alexandra E. Sundberg*, Holly J. Sagerson*, Nasreen Ilias*, Pamela Zobel-Thropp, Elizabeth A. Craig, and Deborah E. Lycan . (2004) Genetic and biochemical interactions among Yar1, Ltv1 and Rps3 define novel links between environmental stress and ribosome biogenesis in Saccharomyces cerevisiae. Genetics 168 :1877-89.
Robert M. Seiser, Alexandra Sundberg*, Bethany Wollam*, Pamela Zobel-Thropp, Katherine Baldwin*, Maxwell Spector*, and Deborah E. Lycan. (2006) Ltv1 is required for efficient nuclear export of the ribosomal small subunit in Saccharomyces cerevisiae. Genetics 174: 1-13.
* Undergraduate co-authors.
Updated: Jan. 10, 2007