title: Initiation of phage infection by partial unfolding and prolyl isomerization.
abstract: Infection of Escherichia coli by the filamentous phage fd starts with the binding of the N2 domain of the phage gene-3-protein to an F pilus. This interaction triggers partial unfolding of the gene-3-protein, cis → trans isomerization at Pro-213, and domain disassembly, thereby exposing its binding site for the ultimate receptor TolA. The trans-proline sets a molecular timer to maintain the binding-active state long enough for the phage to interact with TolA. We elucidated the changes in structure and local stability that lead to partial unfolding and thus to the activation of the gene-3-protein for phage infection. Protein folding and TolA binding experiments were combined with real-time NMR spectroscopy, amide hydrogen exchange measurements, and phage infectivity assays. In combination, the results provide a molecular picture of how a local unfolding reaction couples with prolyl isomerization not only to generate the activated state of a protein but also to maintain it for an extended time.
authors.affiliation: Laboratorium für Biochemie, Universität Bayreuth, D-95440 Bayreuth, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Hoffmann-Thoms
authors.forename: Ulrich
authors.initials: U
authors.lastname: Weininger
authors.forename: Barbara
authors.initials: B
authors.lastname: Eckert
authors.forename: Roman P
authors.initials: RP
authors.lastname: Jakob
authors.forename: Johanna R
authors.initials: JR
authors.lastname: Koch
authors.forename: Jochen
authors.initials: J
authors.lastname: Balbach
authors.forename: Franz X
authors.initials: FX
authors.lastname: Schmid
mesh_terms: D017104:Bacteriophage M13 / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000821:virology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D018933:Pili, Sex / Q000235:genetics / Q000378:metabolism*; D011392:Proline / Q000235:genetics / Q000378:metabolism*; D058767:Protein Unfolding; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D014764:Viral Proteins; C062093:tolA protein, E coli; D011392:Proline
keywords: Gene-3-protein; Molecular Timer; Nuclear Magnetic Resonance; Phage Infection; Prolyl Isomerization; Protein Folding; Protein Stability; Protein Structure; Signal Transduction