Energetic communication between functional sites of the gene-3-protein during infection by phage fd.
To initiate infection of Escherichia coli, phage fd uses its gene-3-protein (G3P) to bind first to an F pilus and then to the TolA protein at the cell surface. G3P is normally auto-inhibited because a tight interaction between the two N-terminal domains N1 and N2 buries the TolA binding site. Binding of N2 to the pilus activates G3P by initiating long-range conformational changes that are relayed to the domain interface and to a proline timer. We discovered that the 23-28 loop of the N1 domain is critical for propagating these conformational signals. The analysis of the stability and the folding dynamics of G3P variants with a shortened loop combined with TolA interaction studies and phage infection experiments reveal how the contact between the N2 domain and the 23-28 loop of N1 is energetically linked with the interdomain region and the proline timer and how it affects phage infectivity. Our results illustrate how conformational transitions and prolyl cis/trans isomerization can be coupled energetically and how conformational signals to and from prolines can be propagated over long distances in proteins.
Laboratorium für Biochemie und Bayreuther Zentrum für Molekulare Biowissenschaften, Universität Bayreuth, D-95440 Bayreuth, Germany.
Stephanie
S
Hoffmann-Thoms
Laboratorium für Biochemie und Bayreuther Zentrum für Molekulare Biowissenschaften, Universität Bayreuth, D-95440 Bayreuth, Germany.
Roman P
RP
Jakob
Laboratorium für Biochemie und Bayreuther Zentrum für Molekulare Biowissenschaften, Universität Bayreuth, D-95440 Bayreuth, Germany. Electronic address: fx.schmid@uni-bayreuth.de.
Franz X
FX
Schmid
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017104:Bacteriophage M13 / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism / Q000821:virology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D017510:Protein Folding; D054730:Protein Interaction Domains and Motifs; D055550:Protein Stability; D017386:Sequence Homology, Amino Acid; D013816:Thermodynamics; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
D029968:Escherichia coli Proteins; D014764:Viral Proteins; C062093:tolA protein, E coli
conformational switch; filamentous phage; prolyl isomerization; signal transduction