title: Targeted mutagenesis of the P22 portal protein reveals the mechanism of signal transmission during DNA packaging.
abstract: The portal vertex in dsDNA bacteriophage serves as the site for genome encapsidation and release. In several of these viruses, efficient termination of DNA packaging has been shown to be dependent on the density of packaged DNA. The portal protein has been implicated as being part of the sensor that regulates packaging termination through DNA-dependent conformational changes during packaging. The mechanism by which DNA induces these conformational changes remains unknown. In this study, we explore how point mutants in the portal core can result in changes in genome packaging density in P22. Mutations in the portal core that subtly alter the structure or dynamics of the protein result in an increase in the amount of DNA packaged. The magnitude of the change is amino acid and location specific. Our findings suggest a mechanism wherein compression of the portal core is an essential aspect of signal transmission during packaging.
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, 845 19th St. South, Birmingham, AL 35294, United States; Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, 3 Blackfan Circle, Boston, MA 02115, United States.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Bedwell
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, 845 19th St. South, Birmingham, AL 35294, United States. Electronic address: prevelig@uab.edu.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Prevelige
mesh_terms: D017100:Bacteriophage P22 / Q000235:genetics* / Q000502:physiology; D036022:Capsid Proteins / Q000378:metabolism*; D042003:DNA Packaging / Q000235:genetics*; D004279:DNA, Viral / Q000235:genetics*; D009690:Nucleic Acid Conformation; D012475:Salmonella / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics; D019065:Virus Assembly / Q000502:physiology*
chemical_list: D036022:Capsid Proteins; D004279:DNA, Viral
keywords: Genome packaging; Packaging motors; Virus assembly; Virus maturation