Advisor(s)
William Placzek
Committee Member(s)
Chad Petit
Matthew Renfrow
Stephen Aller
Terje Dokland
Todd Green
Document Type
Dissertation
Date of Award
6-1-2026
Degree Name
Doctor of Philosophy (PhD)
School
Joint Health Sciences (Interdisciplinary)
Department
Joint Health Sciences
Abstract
Two key aspects of cellular homeostasis are glucose metabolism and apoptosis, making the proteins that control these processes critical regulators of cellular function. The hexokinase family of proteins convert glucose to glucose-6-phosphate, and through this role, are apical regulators of glucose metabolism. The B cell leukemia 2 (Bcl-2) family of proteins are master regulators of apoptosis, which they regulate by controlling mitochondrial outer membrane permeabilization (MOMP). An interaction between hexokinase 2 (HK2) and the Bcl-2 homolog myeloid cell leukemia 1 (MCL1), provides an axis by which cellular homeostasis is controlled, highlighting the importance of understanding these protein families. The interaction between HK2 and MCL1 is mediated by a protein motif known as the reverse Bcl-2 homology 3 (rBH3). This motif has been previously identified in other protein families, including the INK4 family of cyclin inhibitors and the p53 family of transcription factors. I performed a phylogenetic analysis of these protein families to determine the conservation of the rBH3 motif and found that the rBH3 motif is conserved throughout jawed vertebrates. I extended my analysis to look at the conservation of Mcl-1 and found that the binding groove was also conserved throughout jawed vertebrates, confirming that rBH3 interactions are likely preserved, highlighting the importance of rBH3 interactions in cellular function. Continuing my investigation of the proteins underlying cellular homeostasis, I then began to analyze the roles and structures of hexokinase proteins in glucose metabolism. Their unique structural features give rise to specific cellular roles and allow for fine-tuned control of glucose metabolism throughout different tissues and cell types. I found that hexokinase structures were limited by a lack of the apo-structure of bidomain hexokinases, which are the most prevalent class of hexokinases in humans. To this end, I solved the cryo-EM structure of human apo-HK2 to a resolution of 3.5 Å. The apo-structure of HK2 revealed a novel interface between the N-terminal domain and C-terminal domain, providing a molecular mechanism for cross-domain regulation that has been observed in hexokinases. Overall, this work highlights the importance of understanding the structures of proteins involved in maintaining cellular homeostasis to fully appreciate their functions.
Keywords
Apoptosis;Cryo-electron Microscopy;Glucose Metabolism;Hexokinase 2;MCL1;phylogenetics
Recommended Citation
McGriff, Anna Kay, "The Structures Of Homeostasis: Structural Analysis Of Conserved Proteins Across Apoptosis And Glucose Metabolism" (2026). ETDs from 2020-2029. 249.
https://digitalcommons.library.uab.edu/etd-2020s/249
