Chapter category: Viruses
DNA Packaging in Bacteriophage T4
Viral Genome Packaging Machines: Genetics, Structure
and Mechanism
Edited by: Carlos CatalanoISBN: 0-306-48227-4
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Chapter authors:
Venigalla B. Rao and Lindsay W. Black
Double-stranded (ds) DNA packaging in phage T4 and other icosahedral viruses is a fascinating biological problem. During packaging, a complex, metabolically active, concatemeric DNA is translocated into an empty prohead in an ATP-driven process and condensed as a highly ordered structure of near crystalline density.1-3 dsDNA packaging serves as an excellent model system to understand fundamental biological mechanisms such as the reversible condensation and decondensation of DNA, DNA movement along protein complexes, and transduction of ATP hydrolysis energy into mechanical motion of DNA. The phage T4 head assembly pathway produces a complex prohead consisting of six essential proteins and at least seven nonessential proteins.4 The T4 prohead maturation protease degrades the scaffolding core into peptides and cleaves off the N-termini of the major capsid protein (gp23) and the vertex protein (gp24) to generate an empty mature prohead that is competent for DNA packaging. In parallel, the T4 DNA replication pathways generate a highly branched “endless” concatemeric DNA, which is associated with a myriad of protein complexes involved in replication, transcription, recombination and repair. A terminase complex of gp16 (18 kDa) and gp17 (70 kDa) links these two pathways by recognizing the viral concatemer, making an endonucleolytic cut, and joining it to the prohead through specific interactions with the dodecameric portal vertex constituted by gp20 (Table 1). Consequently, a DNA packaging machine is assembled, with the terminase as one of the key components (Fig. 1). This machine translocates an intact, unit-length, linear dsDNA genome into the capsid to form a highly ordered condensed structure. Terminase apparently also makes the second cut terminating DNA packaging, dissociates from the packaged structure, and repeats the DNA linkage to another prohead in a processive fashion.
Additional chapters from this book:
Bacteriophage SPP1 DNA Packaging
Anja Droge and Paulo Tavares
SPP1 is a virulent double-stranded DNA (dsDNA) phage that infects the Gram-positive bacterium Bacillus subtilis strain 168. SPP1 belongs to the Siphoviridae family. The virion is composed of an icos...
DNA Packaging in Bacteriophage T4
Venigalla B. Rao and Lindsay W. Black
Double-stranded (ds) DNA packaging in phage T4 and other icosahedral viruses is a fascinating biological problem. During packaging, a complex, metabolically active, concatemeric DNA is translocated ...
Bacteriophage Lambda Terminase and the Mechanism of Viral DNA Packaging
Michael Feiss and Carlos Enrique Catalano
The developmental pathways of many double-stranded DNA (dsDNA) viruses, both prokaryotic and eukaryotic, are remarkably similar. In viruses as diverse as bacteriophage λ and the herpesviruses, ...
The o29 DNA Packaging Motor: Seeking the Mechanism
Dwight Anderson and Shelley Grimes
The Bacillus subtilis bacteriophage o29 research team in Minneapolis has marveled at (and reveled in) the intricacies of o29 assembly for more than 30 years. Here we highlight the current state of k...
Bacteriophage SPP1 DNA Packaging
Anja Dr?ge and Paulo Tavares
SPP1 is a virulent double-stranded DNA (dsDNA) phage that infects the Gram-positive bacterium Bacillus subtilis strain 168. SPP1 belongs to the Siphoviridae family. The virion is composed of an icos...
DNA Packaging by Bacteriophage P22
Sherwood Casjens and Peter Weigele
Bacteriophage P22 was isolated by Zinder and Lederberg1 a half century ago, and was immediately put to work by Salmonella bacterial geneticists because of its unusual (at that time) DNA packaging pr...
Cleavage and Packaging of Herpes Simplex Virus 1 DNA Herpesvirus Assembly
Joel D. Baines and Sandra K. Weller
Herpes simplex virus DNA accumulates in the nuclei of infected cells as long concatemers. The packaging machinery recognizes signals within the concatemers, cleaves the DNA to generate unit length m...
Encapsidation of the Segmented Double-Stranded RNA Genome of Bacteriophage PHI 6
Minna M. Poranen, Markus J. Pirttimaa and Dennis H. Bamford
Bacteriophage PHI6 has a segmented double-stranded RNA genome that is incorporated into a preformed capsid during the viral assembly. The three viral genomic segments are packaged as single-stranded...
T3/T7 DNA Packaging
Philip Serwer
During formation of a mature bacteriophage particle, a procapsid of protein packages the linear double-stranded DNA genome of the related bacteriophages, T3 and T7. Initiation of T3/T7 DNA packaging...
