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dc.contributor.advisorChairperson, Graduate Committee: Joan B. Brodericken
dc.contributor.authorCrain, Adam Vernonen
dc.contributor.otherKaitlin S. Duschene, John W. Peters and Joan B. Broderick were co-authors of the article, 'Iron sulfur clusters, S-adenosylmetionine enzymes, and their role in hydrogenase maturation' which is contained within this thesis.en
dc.contributor.otherJoan B. Broderick was a co-author of the article, 'Flavodoxin cofactor binding induces structural changes that are required for protein-protein interactions with NADP+ oxidoreductase and pyruvate formate-lyase activating enzyme' which is contained within this thesis.en
dc.contributor.otherJoan B. Broderick was a co-author of the article, 'Pyruvate formate-lyase: protein-protein interactions and activation by pyruvate formate-lyase activating enzyme' which is contained within this thesis.en
dc.contributor.otherStephanie J. Maiocco, Sean J. Elliot and Joan B. Broderick were co-authors of the article, 'Elucidating the role of cation binding in PFL-AE' which is contained within this thesis.en
dc.contributor.otherMartina D. Van Hoy and Joan B. Broderick were co-authors of the article, 'Pyruvate:flavodoxin oxidoreductase is the electron donor for pyruvate formate-lyase activating enzyme' which is contained within this thesis.en
dc.date.accessioned2015-01-13T20:40:43Z
dc.date.available2015-01-13T20:40:43Z
dc.date.issued2013en
dc.identifier.urihttps://scholarworks.montana.edu/xmlui/handle/1/8755en
dc.description.abstractPyruvate formate-lyase activating enzyme (PFL-AE) is one of the best-characterized members of the radical S-adenosyl-L-methionine (SAM) superfamily. The radical SAM enzymes utilize an iron-sulfur cluster and SAM to catalyze a diverse set of reactions such as vitamin synthesis, enzyme activation, DNA repair, and sulfur insertion to name a few. PFL-AE contains one [4Fe-4S] cluster coordinated by cysteine residues from a canonical CX3CX2C radical SAM motif. Iron-sulfur cluster-initiated reductive cleavage of S-adenosylmethionine results in a highly reactive 5'-deoxyadenosyl radical that abstracts a pro-S hydrogen from glycine 734 on PFL creating a stable glycyl radical. PFL utilizes this glycyl radical to catalyze the reaction pyruvate + CoA [] formate + acetyl-CoA, thereby providing the main source of acetyl-CoA for the citric acid cycle under anaerobic conditions. We have undertaken experiments using circular dichroism and isothermal titration calorimetry to characterize interactions between flavodoxin (Fld) and its cofactor (FMN). These experiments show that cofactor binding significantly increases flavodoxin stability and structure, which is required for protein-protein interactions. Anaerobic surface plasmon resonance experiments were used to provide insight into protein-protein interactions between the enzymes involved in PFL activation and in all cases, the proteins interact with low micromolar affinity. SAM binding experiments with PFL-AE were performed in the presence and absence of PFL, which demonstrate that PFL binding to PFL-AE does not alter SAM binding affinity for PFL-AE. PFL activation studies using PFL-AE in the presence of PFL substrates/analogues show that they are not required for PFL activation, however they do play a large role in activation and their inclusion resulted in 3.7 fold higher glycyl radical concentrations. In vivo concentrations were calculated for proteins and small molecules involved in PFL activation and activity in E. coli to provide a context for our measured equilibrium constants and to determine the amount of bound protein in vivo. Activity assays and UV-vis electron transfer assays show that pyruvate:flavodoxin oxidoreductase (PFOR) is capable of activating the PFL system. The aggregate data suggests that electron transfer from Fld to PFL-AE only occurs when SAM and PFL are bound to PFL-AE.en
dc.language.isoenen
dc.publisherMontana State University - Bozeman, College of Letters & Scienceen
dc.subject.lcshAdenosylmethionineen
dc.subject.lcshCharge exchangeen
dc.subject.lcshEnzymesen
dc.titleInteractions and electron transfer involved in pyruvate formate-lyase activationen
dc.typeDissertationen
dc.rights.holderCopyright 2013 by Adam Vernon Crainen
thesis.catalog.ckey2666220en
thesis.degree.committeemembersMembers, Graduate Committee: C. Martin Lawrence; John W. Peters; Eric Shepard; William A. Hochen
thesis.degree.departmentChemistry & Biochemistry.en
thesis.degree.genreDissertationen
thesis.degree.namePhDen
thesis.format.extentfirstpage1en
thesis.format.extentlastpage177en


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