title: Phage phi29 DNA replication organizer membrane protein p16.7 contains a coiled coil and a dimeric, homeodomain-related, functional domain.
abstract: The Bacillus subtilis phage varphi29-encoded membrane protein p16.7 is one of the few proteins known to be involved in prokaryotic membrane-associated DNA replication. Protein p16.7 contains an N-terminal transmembrane domain responsible for membrane localization. A soluble variant lacking the N-terminal membrane anchor, p16.7A, forms dimers in solution, binds to DNA, and has affinity for the varphi29 terminal protein. Here we show that the soluble N-terminal half of p16.7A can form a dimeric coiled coil. However, a second domain, located in the C-terminal half of the protein, has been characterized as being the main domain responsible for p16.7 dimerization. This 70-residue C-terminal domain, named p16.7C, also constitutes the functional part of the protein as it binds to DNA and terminal protein. Sequence alignments, secondary structure predictions, and spectroscopic analyses suggest that p16.7C is evolutionarily related to DNA binding homeodomains, present in many eukaryotic transcriptional regulator proteins. Based on the results, a structural model of p16.7 is presented.
authors.affiliation: Instituto de Biología Molecular "Eladio Viñuela", Centro de Biología Molecular "Severo Ochoa", Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Muñoz-Espín
authors.forename: Mauricio G
authors.initials: MG
authors.lastname: Mateu
authors.forename: Laurentino
authors.initials: L
authors.lastname: Villar
authors.forename: Anabel
authors.initials: A
authors.lastname: Marina
authors.forename: Margarita
authors.initials: M
authors.lastname: Salas
authors.forename: Wilfried J J
authors.initials: WJ
authors.lastname: Meijer
mesh_terms: D000595:Amino Acid Sequence; D017103:Bacillus Phages / Q000737:chemistry* / Q000235:genetics; D001412:Bacillus subtilis / Q000821:virology; D019281:Dimerization; D019143:Evolution, Molecular; D008565:Membrane Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017385:Sequence Homology; D014764:Viral Proteins / Q000737:chemistry*
chemical_list: D008565:Membrane Proteins; D014764:Viral Proteins; C433528:protein p16.7, bacterophage phi29