Figure 2.

The bacteriophage Φ6 life cycle in structures. The virion has three layers surrounding the tripartite dsRNA genome (red): the capsid (beige), the intermediate layer (blue and green), and the proteolipid envelope (cyan). Infection starts when the P3 spike binds to the pilus receptor. The envelope then fuses with the outer membrane, degrades the peptidoglycan layer (P5), and enters, mediated by P8. After P8 disassembles, the host factor YajQ binds to facilitate the transcription of the l segment, so that it is expressed at about the same levels as the s and m segments. The l segment codes for the four proteins assembled into the initial product, the procapsid. The ssRNA segments are then packaged in sequence with corresponding expansion of the capsid shell. Once all the segments are packaged, replication completes the production of the dsRNA genome. The P8 shell is assembled, the envelope added, and the new virion released through cell lysis.