Identifying Electrostatic Interactions Controlling pH-switching in Myristoylated Hisactophilin

dc.contributor.authorMcDonald, Iain
dc.date.accessioned2024-08-30T18:14:53Z
dc.date.available2024-08-30T18:14:53Z
dc.date.issued2024-08-30
dc.date.submitted2024-08-27
dc.description.abstractMyristoyl-switching in proteins is an essential form of functional regulation that controls fundamental biological processes such as signal transduction, protein-membrane interactions, and viral infection. In this form of functional regulation, the reversible switching of a saturated C14 fatty-acyl chain covalently attached to the N-terminus of a protein switches between two states: 1) a sequestered state where the myristoyl group is buried in a hydrophobic environment and 2) a state with increased solvent accessibility where the myristoyl group is available for interaction with binding partners. Myristoyl-switching controls protein function by modulating affinity for membrane and protein binding partners, depending on the accessibility of the hydrophobic myristoyl group. Hisactophilin is a membrane binding protein found in Dictyostelium discoideum responsible for binding and bundling actin in a pH-dependent manner, largely driven by the reversible exposure of its myristoyl group. This protein’s myristoyl switch is controlled by an intramolecular network of electrostatic-hydrophobic interactions; at low pH ~1.5 protons are bound by some of the many ionizable groups, resulting in a conformational shift where the sequestered myristoyl group is made more accessible for insertion into cellular membranes. Through a combination of implicit solvent molecular dynamics simulations and experimental methods, residues D57, H89 and H91 were hypothesized to be the residues controlling myristoyl-switching in hisactophilin. Mutation of these residues indicates that the proposed mechanism of pH-switching in hisactophilin is not fully correct. Design and experimental characterization of follow-up mutants indicates that pH-switching may be controlled through an alternative mechanism. Further investigating the molecular mechanisms of myristoyl-switching in this protein will provide valuable insight into how hydrophobic-electrostatic networks regulate function in allosteric proteins.
dc.identifier.urihttps://hdl.handle.net/10012/20937
dc.language.isoen
dc.pendingfalse
dc.publisherUniversity of Waterlooen
dc.subjectprotein
dc.titleIdentifying Electrostatic Interactions Controlling pH-switching in Myristoylated Hisactophilin
dc.typeMaster Thesis
uws-etd.degreeMaster of Science
uws-etd.degree.departmentChemistry
uws-etd.degree.disciplineChemistry
uws-etd.degree.grantorUniversity of Waterlooen
uws-etd.embargo.terms2 years
uws.contributor.advisorMeiering, Elizabeth
uws.contributor.affiliation1Faculty of Science
uws.peerReviewStatusUnrevieweden
uws.published.cityWaterlooen
uws.published.countryCanadaen
uws.published.provinceOntarioen
uws.scholarLevelGraduateen
uws.typeOfResourceTexten

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