I3-like viruses

Molecular biology

VIRION

Nonenveloped, head-tail structure. The head is about 85 nm in diameter. The capsid has an elongated icosahedral symmetry T=13 Q=21, composed of 152 capsomers.

GENOME

Linear, dsDNA genome of about 156 kb, containing about 225 genes.

GENE EXPRESSION

Genes are transcribed by operons.

REPLICATION

CYTOPLASMIC

  1. Adsorption: the phage attaches to target cell trhough its tail fibers.
  2. Viral lysozyme degrades cell wall locally
  3. Injection: viral DNA is injected in host cell periplasm by contraction of the tail
  4. Transcription and traduction of early genes
  5. Replication of genomic DNA
  6. Transcription and traduction of late genes
  7. Assembly of new virions in host cell cytoplasm
  8. Mature virions are released from the cell by lysis