title: Interaction of packaging motor with the polymerase complex of dsRNA bacteriophage.
abstract: Many viruses employ molecular motors to package their genomes into preformed empty capsids (procapsids). In dsRNA bacteriophages the packaging motor is a hexameric ATPase P4, which is an integral part of the multisubunit procapsid. Structural and biochemical studies revealed a plausible RNA-translocation mechanism for the isolated hexamer. However, little is known about the structure and regulation of the hexamer within the procapsid. Here we use hydrogen-deuterium exchange and mass spectrometry to delineate the interactions of the P4 hexamer with the bacteriophage phi12 procapsid. P4 associates with the procapsid via its C-terminal face. The interactions also stabilize subunit interfaces within the hexamer. The conformation of the virus-bound hexamer is more stable than the hexamer in solution, which is prone to spontaneous ring openings. We propose that the stabilization within the viral capsid increases the packaging processivity and confers selectivity during RNA loading.
authors.affiliation: Institute of Biotechnology and Department of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 1 PL 65, 00014 Helsinki, Finland.
authors.forename: Jirí
authors.initials: J
authors.lastname: Lísal
authors.forename: Denis E
authors.initials: DE
authors.lastname: Kainov
authors.forename: TuKiet T
authors.initials: TT
authors.lastname: Lam
authors.forename: Mark R
authors.initials: MR
authors.lastname: Emmett
authors.forename: Hui
authors.initials: H
authors.lastname: Wei
authors.forename: Paul
authors.initials: P
authors.lastname: Gottlieb
authors.forename: Alan G
authors.initials: AG
authors.lastname: Marshall
authors.forename: Roman
authors.initials: R
authors.lastname: Tuma
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism*; D004926:Escherichia coli / Q000821:virology; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D012317:RNA Phages / Q000201:enzymology* / Q000502:physiology*; D012324:RNA-Dependent RNA Polymerase / Q000737:chemistry / Q000378:metabolism*; D019065:Virus Assembly / Q000502:physiology*
chemical_list: D020409:Molecular Motor Proteins; D012324:RNA-Dependent RNA Polymerase; D000251:Adenosine Triphosphatases