Novel Activities of Kinase-Fold Enzymes from Legionella pneumophila

dc.contributor.advisorCobb, Melanie H.en
dc.contributor.committeeMemberTagliabracci, Vincent S.en
dc.contributor.committeeMemberMendell, Joshua T.en
dc.contributor.committeeMemberOlson, Eric N.en
dc.creatorBlack, Milesen
dc.creator.orcid0000-0002-2864-1710
dc.date.accessioned2022-09-20T17:17:07Z
dc.date.available2022-09-20T17:17:07Z
dc.date.created2020-08
dc.date.issued2020-08-01T05:00:00.000Z
dc.date.submittedAugust 2020
dc.date.updated2022-09-20T17:17:08Z
dc.description.abstractProtein kinases are fundamental mediators of cell signaling that transfer phosphate from ATP to their substrates. The protein kinase superfamily encompasses a vast and diverse trove of enzymes from all domains of life, including remote members that are barely recognizable by their primary amino acid sequence. SidJ (Substrate of Icm/Dot J) is a distant protein kinase homolog from the human pathogen Legionella pneumophila. Contamination of water supplies with Legionella bacteria is a frequent cause of deadly pneumonia outbreaks (Legionnaire's disease). SidJ is a secreted Legionella virulence factor required for bacterial intracellular replication, but it is unknown how SidJ contributes to pathogenesis of Legionnaire's disease, or if SidJ has maintained the kinase fold or catalytic activity. In this work, I determine that SidJ is a calmodulin-binding protein which adopts a protein kinase fold. However, instead of phosphorylation, it catalyzes protein polyglutamylation. SidJ utilizes ATP to form an isopeptide bond between the amino group of free glutamate and the 𝛾-carboxyl group of a glutamate of its substrate. During infection, SidJ polyglutamylates and inactivates a family of Legionella "all-in-one" ubiquitin ligases. Polyglutamylation is crucial step in the intracellular lifecycle of the bacterium and is required for full Legionella virulence in a eukaryotic host. SidJ reveals the unexpected catalytic versatility of the protein kinase fold, and highlights a unique strategy that pathogenic bacteria use to thrive within host cells. Interestingly, SidJ lacks key catalytic residues believed to be required for kinase activity. The discovery that SidJ is a polyglutamylating enzyme suggests that catalytically incompetent or 'pseudo' enzymes may lack activity only when assayed for the wrong reaction.en
dc.format.mimetypeapplication/pdfen
dc.identifier.oclc1345260240
dc.identifier.urihttps://hdl.handle.net/2152.5/9974
dc.language.isoenen
dc.subjectBacterial Proteinsen
dc.subjectLegionella pneumophilaen
dc.subjectPolyglutamic Aciden
dc.subjectProtein Kinasesen
dc.subjectUbiquitin-Protein Ligasesen
dc.subjectUbiquitinationen
dc.subjectVirulence Factorsen
dc.titleNovel Activities of Kinase-Fold Enzymes from Legionella pneumophilaen
dc.typeThesisen
dc.type.materialtexten
thesis.degree.departmentGraduate School of Biomedical Sciencesen
thesis.degree.disciplineCell Regulationen
thesis.degree.grantorUT Southwestern Medical Centeren
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen

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