title: The Transmembrane Morphogenesis Protein gp1 of Filamentous Phages Contains Walker A and Walker B Motifs Essential for Phage Assembly.
abstract: In contrast to lytic phages, filamentous phages are assembled in the inner membrane and secreted across the bacterial envelope without killing the host. For assembly and extrusion of the phage across the host cell wall, filamentous phages code for membrane-embedded morphogenesis proteins. In the outer membrane of Escherichia coli, the protein gp4 forms a pore-like structure, while gp1 and gp11 form a complex in the inner membrane of the host. By comparing sequences with other filamentous phages, we identified putative Walker A and B motifs in gp1 with a conserved lysine in the Walker A motif (K14), and a glutamic and aspartic acid in the Walker B motif (D88, E89). In this work we demonstrate that both, Walker A and Walker B, are essential for phage production. The crucial role of these key residues suggests that gp1 might be a molecular motor driving phage assembly. We further identified essential residues for the function of the assembly complex. Mutations in three out of six cysteine residues abolish phage production. Similarly, two out of six conserved glycine residues are crucial for gp1 function. We hypothesise that the residues represent molecular hinges allowing domain movement for nucleotide binding and phage assembly.
authors.affiliation: Sebastian Leptihn, Institute of Microbiology and Molecular Biology, University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany. belinda.loh@uni-hohenheim.de.
authors.forename: Belinda
authors.initials: B
authors.lastname: Loh
authors.affiliation: Sebastian Leptihn, Institute of Microbiology and Molecular Biology, University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany. Maximilian.Haase@uni-hohenheim.de.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Haase
authors.affiliation: Sebastian Leptihn, Institute of Microbiology and Molecular Biology, University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany. lukas.mueller@uni-hohenheim.de.
authors.forename: Lukas
authors.initials: L
authors.lastname: Mueller
authors.affiliation: Sebastian Leptihn, Institute of Microbiology and Molecular Biology, University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany. andreas.kuhn@uni-hohenheim.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kuhn
authors.affiliation: Sebastian Leptihn, Institute of Microbiology and Molecular Biology, University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany. sebastian.leptihn@uni-hohenheim.de.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Leptihn
mesh_terms: D020816:Amino Acid Motifs; D017104:Bacteriophage M13 / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D017124:Conserved Sequence; D004252:DNA Mutational Analysis; D004926:Escherichia coli / Q000378:metabolism / Q000821:virology; D017912:Inovirus / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism*; D019065:Virus Assembly
chemical_list: D014764:Viral Proteins
keywords: ATPase; M13; Walker motifs; assembly complex; filamentous phage; gp1; membrane protein; molecular hinge; phage assembly; secretion; zonula occludens toxin (Zot)