Membrane Penetration by Bacterial Viruses

The bacteriophage phi 29 infects Gram-positive Bacillus subtilis with a short noncontractile tail. Recent studies showed that the phi 29 tail protein gp9 forms a hexameric tube with six long loops of membrane-active peptides blocking in the tube at the distal end of the tail. The long loops exit on genome release and form a membrane pore for passage of the genome. The membrane penetration mechanism of the phi 29 tail might be common among tailed bacteriophages.