Date on Senior Honors Thesis


Document Type

Senior Honors Thesis

Degree Name




Degree Program

College of Arts and Sciences

Author's Keywords

Prenylation; Moss; MicroRNA; Overlap PCR; Knockdowns


Protein prenylation is a post-translational modification that involves the addition of lipid groups to the carboxy end of a target protein and is necessary for protein activity. Prenylation has important roles in the cell: targeting and localizing proteins to subcellular compartments and promoting protein-protein interactions. As a highly conserved process in eukaryotes, prenylation is especially important for plant development. In contrast to other eukaryotes, in which loss of prenylation components can be lethal, in the flowering plant Arabidopsis thaliana and the moss Physcomitrella patens, most are viable. Prior studies have shown that prenylation is involved in ABA hormone responses, polar cell elongation, and cell fate determination. Maximizing its utility may have important implications in preventing developmental defects in eukaryotes as well as in the development of algae biofuel.

PPAL is an uncharacterized protein whose biochemical function is unknown but is similar in sequence to known prenylation enzymes. Knockouts of PPAL homologs (PPAL1 and PPAL2) in P. patens suggest that PPAL homologs are essential for survival. Preliminary studies knocking down PPAL with previous microRNA constructs indicate its potential role in propagation and growth. Since the moss PPAL knockdown phenotypes displayed in prior studies in the Running lab were not strong, new microRNA constructs were designed to produce PPAL1 and PPAL2 knockdowns with stronger phenotypes to characterize further the functional role of the PPAL genes.

Lay Summary

The colonization of land by plants was a landmark event in the history of life on earth. To survive the harsher, drier, and more extreme terrestrial environment, plants developed specialized structures and cell types for spreading, anchoring, and nutrient uptake, and robust responses to environmental stresses. Our studies of mosses, which are among the earliest land plants, have revealed the role of protein modifications, specifically prenylation, in both developmental and stress response processes that has aided in this adaptation. This study explores the role of a gene called PROTEIN PRENYLTRANSFERASE ALPHA SUBUNIT-LIKE (PPAL); loss of function of this protein results in reduced cell differentiation. Further studies will reveal specific roles of PPAL in plant adaptations to terrestrial environments.