Structural and Molecular Basis for Coordination in a Viral DNA Packaging Motor

• Published in: Cell reports (Cambridge) 2016-03, Vol.14 (8), p.2017-2029
• Main Authors: Mao, Huzhang, Saha, Mitul, Reyes-Aldrete, Emilio, Sherman, Michael B., Woodson, Michael, Atz, Rockney, Grimes, Shelley, Jardine, Paul J., Morais, Marc C.
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - chemistry; Adenosine Triphosphatases - genetics; Adenosine Triphosphatases - metabolism; Adenosine Triphosphate - chemistry; Arginine - chemistry; Bacillus Phages - genetics; Bacillus Phages - metabolism; Bacillus Phages - ultrastructure; Bacillus subtilis - virology; Capsid - metabolism; Capsid - ultrastructure; Cryoelectron Microscopy; Crystallography, X-Ray; DNA - chemistry; DNA - genetics; DNA - metabolism; DNA Packaging; DNA, Viral - chemistry; DNA, Viral - genetics; DNA, Viral - metabolism; Gene Expression; Hydrolysis; Models, Molecular; Protein Domains; Protein Structure, Secondary; Protein Subunits - chemistry; Protein Subunits - genetics; Protein Subunits - metabolism; Viral Proteins - chemistry; Viral Proteins - genetics; Viral Proteins - metabolism; Virus Assembly
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2016.01.058

Ring NTPases are a class of ubiquitous molecular motors involved in basic biological partitioning processes. dsDNA viruses encode ring ATPases that translocate their genomes to near-crystalline densities within pre-assembled viral capsids. Here, X-ray crystallography, cryoEM, and biochemical analyses of the dsDNA packaging motor in bacteriophage phi29 show how individual subunits are arranged in a pentameric ATPase ring and suggest how their activities are coordinated to translocate dsDNA. The resulting pseudo-atomic structure of the motor and accompanying functional analyses show how ATP is bound in the ATPase active site; identify two DNA contacts, including a potential DNA translocating loop; demonstrate that a trans-acting arginine finger is involved in coordinating hydrolysis around the ring; and suggest a functional coupling between the arginine finger and the DNA translocating loop. The ability to visualize the motor in action illuminates how the different motor components interact with each other and with their DNA substrate. [Display omitted] •A nearly complete pseudo-atomic model of a viral dsDNA packaging motor•Two distinct motor-DNA contacts observed in an actively packaging motor•Identified trans-acting arginine finger involved in inter-subunit communication•Proposed mechanism linking ATP hydrolysis, DNA movement, and subunit coordination In a remarkable process, dsDNA viruses work against entropy and electrostatic forces to package their genomes into pre-assembled protein capsids to near crystalline density. Mao et al. describe the structure of the bacteriophage phi29 DNA packaging motor and present biochemical analysis of functional elements involved in motor coordination and translocation.