Date Approved

2026

Degree Type

Open Access Senior Honors Thesis

Department or School

Chemistry

First Advisor

Steven K Backues, Ph.D.

Second Advisor

Heedel Guy Evans, Ph.D.

Third Advisor

Harriet Lindsay, Ph.D.

Abstract

Macroautophagy, or autophagy, is a highly conserved catabolic process in all eukaryotes which allows for the degradation of large cytosolic contents. It occurs in two forms: bulk autophagy, which is induced by nutrient deprivation and targets nonspecific cargo, and selective autophagy, which is induced by cellular stress and sequesters specific substrates. The process of autophagosome formation is carried out by a group of Atg (autophagy-related) proteins, one of which is Atg3. Atg3 functions as an E2-like enzyme by conjugating Atg8 — a ubiquitin-like protein — to phosphatidylethanolamine (PE), a step required for autophagosome membrane formation. This lipidation process is catalyzed by an enzymatic cascade involving Atg7 and the Atg12–Atg5-Atg16 complex. Our research aims to investigate the role of Atg3 in autophagosome size and number. We tested several single, double, and triple Atg3 mutants for partial loss of activity by inducing bulk autophagy via nitrogen starvation. The autophagic throughput of each strain was quantified using a Pho8Δ60 assay. Atg3 mutants H236A and T213S were selected for further analysis because they displayed defects of varying severities, both between each other, and the wild type and atg3Δ strains. Transmission electron microscopy was used to estimate mean size and number of autophagosomes produced by each strain. This allowed us to discern if the observed deficit in autophagic activity was caused by fewer initiations of autophagosome formation or reduced membrane elongation.

Download

EMU Library Accessibility Request

Included in

Chemistry Commons

Share

COinS