An ATP-powered DNA translocation machine encapsidates the viral genome in the large dsDNA bacteriophages. The essential components include the empty shell, prohead, and the packaging enzyme, terminase. During translocation, terminase is docked on the prohead's portal protein. The translocation ATPase and the concatemer-cutting endonuclease reside in terminase. Remarkably, terminases, portal proteins, and shells of tailed bacteriophages and herpes viruses show conserved features. These DNA viruses may have descended from a common ancestor. Terminase's ATPase consists of a classic nucleotide binding fold, most closely resembling that of monomeric helicases. Intriguing models have been proposed for the mechanism of dsDNA translocation, invoking ATP hydrolysis-driven conformational changes of portal or terminase powering DNA motion. Single-molecule studies show that the packaging motor is fast and powerful. Recent advances permit experiments that can critically test the packaging models. The viral genome tran...

The bacteriophage DNA packaging motor.

Solid-state and biological nanopore for real-time sensing of single chemical and sequencing of DNA

2D crystallization: from art to science

Adsorption of biological molecules to a solid support for scanning probe microscopy.

http://www.bioc.rice.edu/~ytao/pdfs/02-cell1998.pdf

Assembly of a Tailed Bacterial Virus and Its Genome Release Studied in Three Dimensions

Three-dimensional reconstruction of the connector of bacteriophage φ29 at 1.8 nm resolution

Template location in noisy pictures

Bacteriophage T3 connector: Three-dimensional structure and comparison with other viral head-tail connecting regions

The 3-D reconstructed images of two related viral structures, obtained by digital image processing from electron micrographs, have been compared to obtain insight into their morphological differences. The viral structures that were studied are the proteins that connect the head to the tail of bacteriophage O29. One of these proteins (p10) is assembled as a dodecamer and, once the DNA has been encapsidated into the viral head, this protein interacts with another viral protein (p11) rendering the viral neck. Biochemical analysis by controlled proteolysis revealed a conformational difference in the structure of p10, depending on whether it is assembled in the connector or in the neck complex. Further structural analysis was carried out by digital image processing and computer graphic techniques. The reconstructed density maps were visualized as solid surface representations to reveal gross morphology, and as translucent models to study the inner details of their structure. The use of different density thresholds also allowed us to distinguish interesting morphological features. A channel present in the connector is closed in the final neck. This closing can be correlated with a rearrangement of the subunits of the connector, probably induced by the interaction of protein p11 with p10.

Juan P. Secilla

Papers

Three-dimensional reconstruction of the connector of bacteriophage φ29 at 1.8 nm resolution

Template location in noisy pictures

Bacteriophage T3 connector: Three-dimensional structure and comparison with other viral head-tail connecting regions

Study of two related configurations of the neck of bacteriophage Ø29