title: The nuclease domain of the SPP1 packaging motor coordinates DNA cleavage and encapsidation.
abstract: The large terminase subunit is a central component of the genome packaging motor from tailed bacteriophages and herpes viruses. This two-domain enzyme has an N-terminal ATPase activity that fuels DNA translocation during packaging and a C-terminal nuclease activity required for initiation and termination of the packaging cycle. Here, we report that bacteriophage SPP1 large terminase (gp2) is a metal-dependent nuclease whose stability and activity are strongly and preferentially enhanced by Mn(2+) ions. Mutation of conserved residues that coordinate Mn(2+) ions in the nuclease catalytic site affect the metal-induced gp2 stabilization and impair both gp2-specific cleavage at the packaging initiation site pac and unspecific nuclease activity. Several of these mutations block also DNA encapsidation without affecting ATP hydrolysis or gp2 C-terminus binding to the procapsid portal vertex. The data are consistent with a mechanism in which the nuclease domain bound to the portal switches between nuclease activity and a coordinated action with the ATPase domain for DNA translocation. This switch of activities of the nuclease domain is critical to achieve the viral chromosome packaging cycle.
authors.affiliation: Unité de Virologie Moléculaire et Structurale, UPR 3296 CNRS, 91190 Gif-sur-Yvette, France.
authors.forename: Charlène
authors.initials: C
authors.lastname: Cornilleau
authors.forename: Noureddine
authors.initials: N
authors.lastname: Atmane
authors.forename: Eric
authors.initials: E
authors.lastname: Jacquet
authors.forename: Callum
authors.initials: C
authors.lastname: Smits
authors.forename: Juan C
authors.initials: JC
authors.lastname: Alonso
authors.forename: Paulo
authors.initials: P
authors.lastname: Tavares
authors.forename: Leonor
authors.initials: L
authors.lastname: Oliveira
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017103:Bacillus Phages / Q000502:physiology; D002213:Capsid / Q000378:metabolism; D020134:Catalytic Domain; D002413:Cations, Divalent; D053837:DNA Cleavage; D042003:DNA Packaging; D004706:Endodeoxyribonucleases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008345:Manganese; D008670:Metals / Q000737:chemistry; D009154:Mutation; D010641:Phenotype; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity; D014764:Viral Proteins / Q000378:metabolism
chemical_list: D002413:Cations, Divalent; D008670:Metals; D014764:Viral Proteins; C417248:bacteriophage SPP1 terminase; C115880:portal protein, Bacteriophage SPP1; D008345:Manganese; D004706:Endodeoxyribonucleases; D000251:Adenosine Triphosphatases