title: Role of bacteriophage SPP1 tail spike protein gp21 on host cell receptor binding and trigger of phage DNA ejection.
abstract: Bacteriophages recognize and bind specific receptors to infect suitable hosts. Bacteriophage SPP1 targets at least two receptors of the Bacillus subtilis cell envelope, the glucosylated wall teichoic acids and the membrane protein YueB. Here, we identify a key virion protein for YueB binding and for the trigger of DNA ejection. Extracts from B. subtilis-infected cells applied to a YueB affinity matrix led to preferential capturing of gp21 from SPP1. To assess the significance of this interaction, we isolated mutant phages specifically affected in YueB binding. The mutants exhibited a very low inactivation rate and a strong defect to eject DNA when challenged with YueB. The phenotype correlated with presence of a single amino acid substitution in the gp21 carboxyl terminus, defining a region involved in YueB binding. Immunoelectron microscopy located the gp21 N-terminus in the SPP1 cap and probably in the adjacent tail spike region whereas the gp21 C-terminus was mapped further down in the spike structure. Antibodies against this part of gp21 interfered with the interaction of YueB with SPP1 and triggered DNA ejection. The gp21 C-terminal region thus plays a central role in two early key events that commit the virus to deliver its genome into host cells.
authors.affiliation: Centro de Patogénese Molecular, Faculdade de Farmácia da Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal.
authors.forename: Inês
authors.initials: I
authors.lastname: Vinga
authors.forename: Catarina
authors.initials: C
authors.lastname: Baptista
authors.forename: Isabelle
authors.initials: I
authors.lastname: Auzat
authors.forename: Isabelle
authors.initials: I
authors.lastname: Petipas
authors.forename: Rudi
authors.initials: R
authors.lastname: Lurz
authors.forename: Paulo
authors.initials: P
authors.lastname: Tavares
authors.forename: Mário A
authors.initials: MA
authors.lastname: Santos
authors.forename: Carlos
authors.initials: C
authors.lastname: São-José
mesh_terms: D017103:Bacillus Phages / Q000502:physiology*; D001412:Bacillus subtilis / Q000821:virology*; D001426:Bacterial Proteins / Q000378:metabolism; D004252:DNA Mutational Analysis; D004279:DNA, Viral / Q000378:metabolism*; D006026:Glycoside Hydrolases; D006790:Host-Parasite Interactions; D008565:Membrane Proteins / Q000378:metabolism; D016253:Microscopy, Immunoelectron; D020125:Mutation, Missense; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017376:Viral Tail Proteins / Q000235:genetics / Q000378:metabolism*; D014771:Virion / Q000737:chemistry / Q000648:ultrastructure; D053585:Virus Attachment; D053586:Virus Internalization
chemical_list: D001426:Bacterial Proteins; D004279:DNA, Viral; D008565:Membrane Proteins; D017376:Viral Tail Proteins; D006026:Glycoside Hydrolases; C083268:tailspike protein, bacteriophage