title: Structure and mechanism of the ATPase that powers viral genome packaging.
abstract: Many viruses package their genomes into procapsids using an ATPase machine that is among the most powerful known biological motors. However, how this motor couples ATP hydrolysis to DNA translocation is still unknown. Here, we introduce a model system with unique properties for studying motor structure and mechanism. We describe crystal structures of the packaging motor ATPase domain that exhibit nucleotide-dependent conformational changes involving a large rotation of an entire subdomain. We also identify the arginine finger residue that catalyzes ATP hydrolysis in a neighboring motor subunit, illustrating that previous models for motor structure need revision. Our findings allow us to derive a structural model for the motor ring, which we validate using small-angle X-ray scattering and comparisons with previously published data. We illustrate the model's predictive power by identifying the motor's DNA-binding and assembly motifs. Finally, we integrate our results to propose a mechanistic model for DNA translocation by this molecular machine.
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605;
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: Hilbert
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605;
authors.forename: Janelle A
authors.initials: JA
authors.lastname: Hayes
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605;
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Stone
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605;
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Duffy
authors.affiliation: Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720.
authors.forename: Banumathi
authors.initials: B
authors.lastname: Sankaran
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605; brian.kelch@umassmed.edu.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Kelch
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001120:Arginine / Q000378:metabolism; D001435:Bacteriophages / Q000201:enzymology* / Q000235:genetics*; D055592:Biophysical Phenomena; D042003:DNA Packaging; D004591:Electrophoresis, Polyacrylamide Gel; D016679:Genome, Viral; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D015203:Reproducibility of Results; D016963:Thermus thermophilus / Q000821:virology; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism; D019065:Virus Assembly
chemical_list: D014764:Viral Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D001120:Arginine; D000251:Adenosine Triphosphatases
keywords: ASCE ATPase; bacteriophage; motor protein; thermophile; translocase