Elizabeth J. Grayhack, Ph.D.

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Functional Proteomics: The wealth of sequenced genomes has resulted in the development of powerful genomic approaches to define the functions of the individual genes, to deduce the networks of interactions between genes and to mine additional information encoded in the genome. For example, a collection of 5,854 sequence-verified yeast expression plasmids (constructed in collaboration with Eric Phizicky, Mark Dumont and Mike Snyder) has opened the door to study signals within genes that regulate their expression. We observe 1,000 fold differences in expression of genes in this collection, despite the fact that all ORFs are expressed using the same set of extragenic regulatory signals. Thus, the ORFs themselves or their protein products are esponsible for these large differences in expression. Analysis of this collection has led to the two projects described below.

The roles of codons in gene expression and regulation: Although accurate and efficient translation of mRNA into proteins is crucially important for the cell, not all of the 61 codons that specify insertion of amino acids into nascent polypeptides behave equally in this process. In fact, almost all synonymous codons, i.e. those that specify the same amino acid, are used at very different frequencies within most organisms, including the yeast S. cerevisiae Although codon use has been implicated as a determinant of expression levels, neither the identity, nor the defining characteristics of codons that impair expression are known. Studies in the Grayhack laboratory are designed to define the rules and mechanisms by which specific codons, and arrangements of codons, impair gene expression, and to identify regulatory models dictated by codon usage in the yeast genome.

Developing yeast to express protein complexes for structural analysis: The structures of many eukaryotic proteins and protein complexes are still unknown because many eukaryotic proteins are either not soluble in E. coli or bear post-translational modifications that are not added in E. coli. To this end we developed a general solution to incorporate selenomethionine into proteins expressed in this yeast, for use in MAD phasing. In addition, we have developed vectors for simultaneous high level expression and affinity purification of protein complexes from S. cerevisiae. Our current goal is to explore the limits of protein expression, solubility and folding to learn in part how yeast differs from E. coli, and what factors contribute most to gene expression.

Current Appointments

• Associate Professor - Department of Biochemistry and Biophysics (SMD)

Education
PhD Biology	Cornell University	1981
BA Chemistry	Lawrence University	1974

Lab Website

http://dbb.urmc.rochester.edu/labs/grayhack/index.html

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Recent Journal Articles
Showing the 5 most recent journal articles. (24 available)
Quartley E; Alexandrov A; Mikucki M; Buckner FS; Hol WG; Detitta GT; Phizicky EM; Grayhack EJ. "Heterologous expression of L. major proteins in S. cerevisiae: a test of solubility, purity, and gene recoding." Journal of structural and functional genomics. 2009; Epub 2009 Aug 22.
Jackman, J. E.; Grayhack, E. J.; Phizicky, E. M.;. "The use of Saccharomyces cerevisiae proteomic libraries to identify RNA-modifying proteins". Methods Mol Biol 488 (2008): 383-93.
Chernyakov, I.; Baker, M. A.; Grayhack, E. J.; Phizicky, E. M.;. "Chapter 11. Identification and analysis of tRNAs that are degraded in Saccharomyces cerevisiae due to lack of modifications". Methods Enzymol 449 (2008): 221-37.
Kotelawala, L.; Grayhack, E. J.; Phizicky, E. M.;. "Identification of yeast tRNA Um(44) 2'-O-methyltransferase (Trm44) and demonstration of a Trm44 role in sustaining levels of specific tRNA(Ser) species". Rna 14 (2008): 158-69.
Chernyakov, I.; Whipple, J. M.; Kotelawala, L.; Grayhack, E. J.; Phizicky, E. M.;. "Degradation of several hypomodified mature tRNA species in Saccharomyces cerevisiae is mediated by Met22 and the 5'-3' exonucleases Rat1 and Xrn1". Genes Dev 22 (2008): 1369-80.