title: Phage T5 straight tail fiber is a multifunctional protein acting as a tape measure and carrying fusogenic and muralytic activities.
abstract: We report a bioinformatic and functional characterization of Pb2, a 121-kDa multimeric protein that forms phage T5 straight fiber and is implicated in DNA transfer into the host. Pb2 was predicted to consist of three domains. Region I (residues 1-1030) was mainly organized in coiled coil and shared features of tape measure proteins. Region II (residues 1030-1076) contained two alpha-helical transmembrane segments. Region III (residues 1135-1148) included a metallopeptidase motif. A truncated version of Pb2 (Pb2-Cterm, residues 964-1148) was expressed and purified. Pb2-Cterm shared common features with fusogenic membrane polypeptides. It formed oligomeric structures and inserted into liposomes triggering their fusion. Pb2-Cterm caused beta-galactosidase release from Escherichia coli cells and in vitro peptidoglycan hydrolysis. Based on these multifunctional properties, we propose that binding of phage T5 to its receptor triggers large conformational changes in Pb2. The coiled coil region would serve as a sensor for triggering the opening of the head-tail connector. The C-terminal region would gain access to the host envelope, permitting the local degradation of the peptidoglycan and the formation of the DNA pore by fusion of the two membranes.
authors: Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Université Paris-Sud, Orsay, France.
authors: Pascale
authors: P
authors: Boulanger
authors: Pierre
authors: P
authors: Jacquot
authors: Laure
authors: L
authors: Plançon
authors: Mohamed
authors: M
authors: Chami
authors: Andreas
authors: A
authors: Engel
authors: Claudine
authors: C
authors: Parquet
authors: Chantal
authors: C
authors: Herbeuval
authors: Lucienne
authors: L
authors: Letellier
mesh_terms: D000595:Amino Acid Sequence; D001435:Bacteriophages / Q000737:chemistry*; D019295:Computational Biology / Q000379:methods; D004279:DNA, Viral / Q000737:chemistry; D006868:Hydrolysis; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013395:Sucrose / Q000737:chemistry; D013997:Time Factors; D014764:Viral Proteins / Q000737:chemistry*; D017376:Viral Tail Proteins / Q000737:chemistry* / Q000502:physiology
chemical_list: D004279:DNA, Viral; D010455:Peptides; D011134:Polysaccharides; D014764:Viral Proteins; D017376:Viral Tail Proteins; D013395:Sucrose