Dissertations and Theses (Open Access)
Author ORCID Identifier
0000-0001-9612-5913
Date of Graduation
8-2026
Document Type
Thesis (MS)
Program Affiliation
Microbiology and Molecular Genetics
Degree Name
Masters of Science (MS)
Advisor/Committee Chair
Ambro van Hoof
Committee Member
Heidi B. Kaplan
Committee Member
Kevin Morano
Committee Member
Catherine Denicourt
Committee Member
Michael Lorenz
Abstract
In yeast, the major mRNA decay pathway involves deadenylation of the 3’ poly-A tail, followed by decapping of the 5’ m7Gppp cap and subsequent 5’ to 3’ degradation or 3’ to 5’ degradation. This is carried out by Pan2/Pan3 and Ccr4/Not deadenylases, the decapping enzyme Dcp2, and Xrn1 and RNA exosome exoribonucleases, respectively. The eukaryotic mRNA decapping enzyme complex, Dcp1/Dcp2, is essential in yeast, and deletion of either gene is lethal. However, the deadenylases that act upstream and the 5’ exoribonuclease that act downstream of the decapping step are not, even though they are all highly conserved with no known redundant genes. This lethality can be rescued by suppressor mutations, including mutations in the karyopherin, KAP123, and the leucine tRNA, TL(GAG)G. These mutations restore viability in dcp2∆, but do not improve bulk mRNA decay rates. This suggests that one or more Dcp2 essential activities are independent of mRNA decay. Dcp2 possesses a small amino-terminus containing its catalytic domain and a large, disordered carboxyl-terminus known to facilitate interactions with multiple proteins, including enhancers of decapping (Edc1,Edc3). Here, using Saccharomyces cerevisiae as a genetic tool, I examined the essential nature of Dcp2 by exploring the functional domains of the protein. Specifically, I investigated the activity of its enzymatic N-terminus, and the broader functionality of the protein-protein interacting C-terminus. This study confirms that Dcp2 catalytic residues are essential for viability, and that Dcp2 requires its first 234 amino acids for viability in yeast. These findings suggest that most of the protein-protein interactions facilitated by Dcp2 C-terminus are not crucial for Dcp2 essential activity in yeast, even though these interactions are known to help with target specificity during mRNA decay. The essentiality of the catalytic residues also indicates that Dcp2’s essential activity requires hydrolysis, and Dcp2 therefore must have a substrate whose hydrolysis is critical for yeast viability.
Recommended Citation
Ewan, Jellisa and van Hoof, Ambro, "Mutational Analysis of Domain Functions in the Yeast Decapping Enzyme Dcp2" (2026). Dissertations and Theses (Open Access). 1590.
https://digitalcommons.library.tmc.edu/utgsbs_dissertations/1590
Keywords
Dcp2, mRNA decay