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Modulation of bacteriophage T4 capsid size
1Department of Microbiology and Molecular Genetics and Molecular Biology Institute, UCLA 90095-1570, USA.
Virology
|July 1, 1996
Summary
Bacteriophage T4 capsid assembly bypass mutations in gene 23 allow for head length control without vertex protein (gp24). These mutations, particularly when combined with specific gene 23 mutations, modulate head length by altering gp23-gp24 interactions.
Area of Science:
- Molecular Biology
- Virology
- Structural Biology
Background:
- Bacteriophage T4 capsid assembly is a complex process.
- The vertex protein (gp24) is essential for T4 capsid assembly.
- Mutations in the major capsid protein (gp23) can bypass the need for gp24.
Purpose of the Study:
- To investigate the role of gp24 in bacteriophage T4 head length control.
- To understand how mutations in gene 23 affect capsid assembly in the absence of gp24.
- To elucidate the interaction between gp23 and gp24 in modulating head length.
Main Methods:
- Isolation and characterization of bacteriophage T4 bypass mutants.
- Genetic analysis including back-crossing mutations with wild-type phage.
- Sequencing of gene 23 in bypass mutants to identify additional mutations.
- Measurement of capsid lengths in various mutant strains.
Main Results:
- gp24 is absent in the capsids of several gp24 bypass mutants.
- Certain bypass mutations lead to the production of short-headed ("petite") phage.
- The ability to produce petite phage is a common feature of bypass mutations.
- Additional missense mutations in gene 23 are found in petite phage-producing bypass mutants.
Conclusions:
- gp24 does not directly regulate bacteriophage T4 head length.
- gp23-gp24 interactions, modulated by specific gene 23 mutations, influence head length control.
- Bypass mutations in gene 23, in conjunction with certain gene 23 mutations, can alter capsid size.
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