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ORCID

https://orcid.org/0000-0002-6303-5003

Access Type

Open Access Thesis

Document Type

thesis

Degree Program

Molecular & Cellular Biology

Degree Type

Master of Science (M.S.)

Year Degree Awarded

2021

Month Degree Awarded

September

Abstract

Molecular chaperones play a key role in maintaining a healthy cellular proteome by performing protein quality control. Heat shock protein 70s (Hsp70s) are a diverse class of evolutionarily conserved chaperones that interact with short hydrophobic sequences presented in unfolded proteins, promoting productive folding, and preventing proteins from aggregation. Most of the extensive research on chaperone examines mechanism, substrate promiscuity, and engagement with many co-chaperones. Only recently were chaperones recognized to be frequent targets of post-translational modifications (PTMs). Despite the recent rise in PTMs identified, the impact of these modifications on chaperone function, whether singular or in concert with other modifications, remains elusive. To investigate the impact of PTMs on chaperone function, we chose to characterize two sites of phosphorylation on the linker of HspA1, the stress inducible human Hsp70. To mimic these phosphoserines, we used aspartate as a phosphomimetic substitution for all experiments. Interdomain allostery ties together chaperone structure and function. Therefore, the impact of phosphorylation on interdomain allostery is probed using biophysical and biochemical techniques. Altogether, data suggest that phosphorylation of the linker and SBD destabilizes the chaperone, while shifting the population towards the docked state. This result alludes to a previously described region of the protein that uncouples domain docking from conformational changes in the substrate-binding domain. The cross-communication between these phosphorylation sites reveals a novel, synergistic effect on chaperone structure and function.

DOI

https://doi.org/10.7275/24584328.0

First Advisor

Lila Gierasch

Second Advisor

Andrew Truman

Third Advisor

Peter Chien

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