Nucleotide-dependent DNA gripping and an end-clamp mechanism regulate the bacteriophage T4 viral packaging motor

The control of form or shape inheritance can be approached by studying the morphogenesis of bacterial viruses. Shape variants of bacteriophage T4 with altered protein shell (capsid) size and nucleic acid (DNA) content have been found by electron microscopy, and a mutant (E920g in gene 66) controlling head size has been described. This mutant produces short-headed particles which contain 2/3 the normal DNA content and which are non-viable when only one particle infects a cell (Fig. 1).We report here the isolation of a new mutant (191c) which also appears to be in gene 66 but at a site distinct from E920g. The most striking phenotype of the mutant is the production of about 10% of the phage yield as “giant” virus particles, from 3 to 8 times longer than normal phage (Fig. 2).

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Faculty Opinions recommendation of Intronless homing: site-specific endonuclease SegF of bacteriophage T4 mediates localized marker exclusion analogous to homing endonucleases of group I introns.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1006527.82256 ◽

2002 ◽

Author(s):

Eric Miller

Keyword(s):

Bacteriophage T4 ◽

Group I Introns ◽

Homing Endonucleases ◽

Site Specific ◽

Group I

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Faculty Opinions recommendation of The baseplate wedges of bacteriophage T4 spontaneously assemble into hubless baseplate-like structure in vitro.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.718180334.793487062 ◽

2013 ◽

Author(s):

Alain Filloux

Keyword(s):

Bacteriophage T4

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The Synergy between CRISPR and Chemical Engineering

Current Gene Therapy ◽

10.2174/1566523219666190701100556 ◽

2019 ◽

Vol 19 (3) ◽

pp. 147-171

Author(s):

Cia-Hin Lau ◽

Chung Tin

Keyword(s):

Viral Vectors ◽

Chemical Engineering ◽

Target Genes ◽

New Technologies ◽

Rapid Development ◽

Genetic Circuits ◽

Viral Packaging ◽

Conditional Control ◽

Logic Operations

Gene therapy and transgenic research have advanced quickly in recent years due to the development of CRISPR technology. The rapid development of CRISPR technology has been largely benefited by chemical engineering. Firstly, chemical or synthetic substance enables spatiotemporal and conditional control of Cas9 or dCas9 activities. It prevents the leaky expression of CRISPR components, as well as minimizes toxicity and off-target effects. Multi-input logic operations and complex genetic circuits can also be implemented via multiplexed and orthogonal regulation of target genes. Secondly, rational chemical modifications to the sgRNA enhance gene editing efficiency and specificity by improving sgRNA stability and binding affinity to on-target genomic loci, and hence reducing off-target mismatches and systemic immunogenicity. Chemically-modified Cas9 mRNA is also more active and less immunogenic than the native mRNA. Thirdly, nonviral vehicles can circumvent the challenges associated with viral packaging and production through the delivery of Cas9-sgRNA ribonucleoprotein complex or large Cas9 expression plasmids. Multi-functional nanovectors enhance genome editing in vivo by overcoming multiple physiological barriers, enabling ligand-targeted cellular uptake, and blood-brain barrier crossing. Chemical engineering can also facilitate viral-based delivery by improving vector internalization, allowing tissue-specific transgene expression, and preventing inactivation of the viral vectors in vivo. This review aims to discuss how chemical engineering has helped improve existing CRISPR applications and enable new technologies for biomedical research. The usefulness, advantages, and molecular action for each chemical engineering approach are also highlighted.

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