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Filamentous phage assembly
1Rockefeller University, New York, New York 10021.
Abstract:
Filamentous phages present a genetically well-defined system for studying the ordered membrane assembly of five different phage-encoded proteins around the circular single-stranded DNA phage genome. Assembly occurs at high efficiency in vivo, catalysed by two phage-encoded membrane proteins and at least one host protein, thioredoxin. This review presents a description of the virion and its cytoplasmic precursor and summarizes the results of genetic and biochemical experiments that are beginning to elucidate the role of the three morphogenetic proteins. The recent discovery of bacterial transport proteins with homology to a phage morphogenetic protein located in the outer membrane suggests the existence of a common mechanism for moving complex macromolecules across bacterial membranes.
Insights
Filamentous phages offer a model system for studying protein assembly at bacterial membranes. Research reveals insights into the roles of key phage proteins in this efficient in vivo process.
Area of Science:
- Molecular Biology
- Virology
- Biochemistry
Background:
- Filamentous phages provide a genetically tractable system to investigate protein assembly.
- The assembly process involves multiple phage-encoded proteins and host factors like thioredoxin.
- Understanding this assembly is crucial for deciphering macromolecule transport across membranes.
Purpose of the Study:
- To describe the structure of filamentous phage virions and their cytoplasmic precursors.
- To summarize genetic and biochemical findings on the roles of morphogenetic proteins.
- To explore potential common mechanisms for macromolecule transport across bacterial membranes.
Main Methods:
- Genetic analysis of phage-encoded proteins.
- Biochemical experiments to characterize protein functions.
- Comparative analysis with bacterial transport proteins.
Main Results:
- Detailed description of the virion and cytoplasmic precursor structures.
- Elucidation of the roles of three key morphogenetic proteins in assembly.
- Identification of homology between phage morphogenetic proteins and bacterial transport proteins.
Conclusions:
- Filamentous phage assembly is a highly efficient in vivo process.
- The study advances understanding of the roles of specific phage proteins in membrane assembly.
- Homology suggests a conserved mechanism for transporting macromolecules across bacterial membranes.