VIRION
Icosahedral pseudo T=21 capsid, 56 nm in diameter, composed of 1200 P1 (spike) and 60 P2 (capsid) proteins. The pentameric receptor-binding spikes are protruding from the 12 fivefold axes. The capsid encloses an internal lipid core containing the structural proteins P3 to P9.
- Double jelly roll-fold major capsid protein [MCP P2]
- Triple jelly roll-fold penton capsid protein [Spike P1]
GENOME
Circular, supercoiled dsDNA genome of about 10 kb encoding for 21 proteins. Displays a very high number of negative supercoils.
GENE EXPRESSION
The genome is organized in three operons.
ENZYMES
REPLICATION
CYTOPLASMIC
- Adsorption: The phage attaches to target cell adhesion receptors.
- The capsid disintegrates and the inner capsid membrane is uncovered. This membrane then fuses with host outer membrane, releasing the viral DNA into the periplasm.
- penetration of the viral into the host cytoplasm.
- Transcription and translation of early genes.
- Replication of genomic DNA via a rolling circle mechanism.
- Transcription and translation of late genes.
- Capsid proteins polymerize around a lipoprotein vesicle translocated in the cytoplasm by virion assembly factors.
- Genomic DNA is packaged in new virions.
- Mature virions are released from the cell by lysis.