Bacteriophage is a term used to describe viruses that infect bacteria and archaea. While most phages are ‘micro predators’ that kill their bacterial hosts, filamentous phages collaborate with their hosts. These viruses are even simpler than the T-phage studied by the phage group, owing to their ease of manipulating their genetic contents. Filamentous phages have a low burden on bacteria and compensate by providing services that aid in the formation of better biofilms, delivering toxins and other factors that increase virulence, or modifying their behavior to provide novel motile activity to their bacterial hosts.
|Some aspects of the reproductive life cycle of bacteriophage M13 are depicted schematically. Credit: what-when-how|
Filamentous phage replication, like that of other bacteriophages, occurs in the cytoplasm of the host bacteria. Adsorption into the host cell occurs via pilus-mediated adsorption. Replication is governed by the ssDNA rolling circle model. DNA-templated transcription is the transcription method used. Viral extrusion is the process by which the virus exits the host cell. In Gram-negative bacteria, viral assembly occurs at the inner membrane and is mediated by a motor protein complex embedded in the membrane. This multimeric assembly complex, which includes the ATPase p1 encoded by gene 1, is thought to mediate the hydrolysis of ATP, providing energy for phage filament assembly.
Filamentous bacteriophage genome
Structure and genome size
Assembly of the filamentous phage virions (In detail)
|M13 bacteriophage particle, genome, and life cycle. Credit: Smeal et al 2017|