Gene W is one of the 10 genes that control the morphogenesis of the bacteriophage lambda head. The morpho genesis of the phage lambda head proceeds through the synthesis of an intermediate assembly called the prohead. This is an empty shell into which the bacteriophage DNA is introduced--packaged--by the phage enzyme DNA terminase. The product of W (gpW) acts after DNA packaging, but before the addition of another phage product, gene product FII, and before the addition of tails. The role of gpW is unknown. The structure of N- and C-tagged gpW has been previously determined by nuclear magnetic resonance (NMR) spectroscopy. Here we report some of the properties of the native protein. The purification of gpW to homogeneity, overproduced by a plasmid derivative, is described. To obtain large amounts of the protein, the ribosome-binding site had to be modified, showing that inefficient translation of the message is the main mechanism limiting W gene expression. The molecular weight of the protein is in close agreement to the value predicted from the DNA sequence of the gene, which suggests that it is not post-transcriptionally modified. It behaves as a monomer in solution. Radioactively labeled gpW is incorporated into phage particles in in vitro complementation, showing that gpW is a structural protein. The stage at which gpW functions and other circumstantial evidence support the idea that six molecules of gpW polymerize on the connector before the incorporation of six molecules of gpFII and before the tail attaches.
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http://dx.doi.org/10.1139/o03-059 | DOI Listing |
Methods Mol Biol
December 2024
Department of Physics, University of California San Diego, La Jolla, CA, USA.
Viral DNA packaging is a required step in the assembly of many dsDNA viruses. A molecular motor fueled by ATP hydrolysis packages the viral genome to near crystalline density inside a pre-formed prohead shell in ~5 min at room temperature in vitro. We describe procedures for measuring the packaging of single DNA molecules into single viral proheads with optical tweezers.
View Article and Find Full Text PDFEcoSal Plus
December 2024
Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
Bacteriophage λ is a paradigm in the field of gene regulation and one of the best-understood systems in genetic regulatory biology. A so-called Genetic Switch determines the mechanisms by which λ transitions to its dual lifestyles-lytic or lysogenic. When λ initiates the lysogenic lifestyle, the phage-encoded CI repressor binds cooperatively to multi-partite operators in a defined pattern that autoregulates repression of phage lytic promoters as well as activation of the lysogenic promoter.
View Article and Find Full Text PDFVaccines (Basel)
October 2024
Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
Nucleic Acids Res
December 2024
Department of Cellular and Molecular Medicine, University of California, San Diego, 9500 Gilman Dr. La Jolla, CA 92093, USA.
Bacteria encode a wide array of immune systems to protect themselves against ubiquitous bacteriophages and foreign DNA elements. While these systems' molecular mechanisms are becoming increasingly well known, their regulation remains poorly understood. Here, we show that an immune system-associated transcriptional repressor of the wHTH-WYL-WCX family, CapW, directly binds single-stranded DNA to sense DNA damage and activate expression of its associated immune system.
View Article and Find Full Text PDFVirus Evol
October 2024
CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France.
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