The role of tyrosines in bacterial iron acquisition by periplasmic ferric binding proteins

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dc.contributor.advisorSchryvers, Anthony B.
dc.contributor.authorKhambati, Husain K.
dc.date.accessioned2017-12-18T22:32:23Z
dc.date.available2017-12-18T22:32:23Z
dc.date.issued2009
dc.descriptionBibliography: p. 120-133en
dc.descriptionMany pages are in colour.en
dc.description.abstractThe human host-specific Gram-negative human pathogen H. influenzae and the porcine pathogen A. pleuropneumoniae can utilize transferrin as their main source of iron for growth. A surface receptor complex made of transferrin binding proteins (TbpA and TbpB) facilitate the release of iron from host transferrin into the periplasm, where it is, in turn, sequestered by a periplasmic iron binding protein. In H. influenzae, this protein is called ferric binding protein A (FbpA). The iron coordination site of FbpA is analogous to that of transferrin and lactoferrin, giving it the term, bacterial transferrin. The results from structural and functional studies in this thesis support a model in which the initial step in iron binding is mediated by a pair of adjacent tyrosines on the C-terminal domain of FbpA. A series of site-directed mutants of the adjacent tyrosine residues show abrogation of iron binding ability in in vitro binding studies and a severe defect in iron transport in a reconstituted H. influenzae FbpABC pathway in E. coli; this is in support of prior evidence discovered for host glycoproteins transferrin and lactoferrin. Collectively these results demonstrate that the presence of a twin-tyrosine motif common to many periplasmic iron binding proteins is critical for initially capturing the ferric iron released by the outer membrane receptor complex. Also characterized in this thesis is periplasmic protein AfuA, identified previously as a functional homologue of FbpA. Sequence analysis and in vitro binding assays demonstrate, however, that AfuA is not a true FbpA homologue, but rather may represent a novel class of ferrous binding proteins. A reconstituted afuABC operon in a specialized iron-deficient strain of E. coli was found to be capable of periplasm-to-cytoplasm iron transport.
dc.format.extentxiii, 133 leaves : ill. ; 30 cm.en
dc.identifier.citationKhambati, H. K. (2009). The role of tyrosines in bacterial iron acquisition by periplasmic ferric binding proteins (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/4808en_US
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/4808
dc.identifier.urihttp://hdl.handle.net/1880/105809
dc.language.isoeng
dc.publisher.institutionUniversity of Calgaryen
dc.publisher.placeCalgaryen
dc.rightsUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.titleThe role of tyrosines in bacterial iron acquisition by periplasmic ferric binding proteins
dc.typemaster thesis
thesis.degree.disciplineMicrobiology & Infectious Diseases
thesis.degree.grantorUniversity of Calgary
thesis.degree.nameMaster of Science (MSc)
ucalgary.item.requestcopytrue
ucalgary.thesis.accessionTheses Collection 58.002:Box 2079 627942951
ucalgary.thesis.notesUARCen
ucalgary.thesis.uarcreleaseyen
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