Bacterial viruses

Very complex shape, requiring 20 gene products for assembly - Capsid (head), contains linear dsDNA genome - Tail, consists of sheath plus internal tube Bacteriophage T4 Figure 11.2

Phage T4 binds to E. coli by contact between its tail fibers and the outer membrane. - A conformational change causes sheath to contract and inject the genome into the cell. Bacteriophage T4 Figure 11.4

Fig Nucleases DNA polymerase New sigma factors Phage DNA Infection Early mRNA Early proteins Phage DNA replication Middle mRNALate mRNA Late proteinsMiddle proteins Self assembly Phage head proteins Tail, collar, base plate, and tail fiber proteins Mature phage particle T4 lysozyme production Lysis Minutes 1050

Progeny genomes are linked in a concatemer. - Cut with an offset, so that individual linear genomes have slight overlaps Figure 11.7

Figure 11.6 Replicative Cycle of Bacteriophage T4

Progeny genomes are linked in a concatemer. - Cut with an offset, so that individual linear genomes have slight overlaps Figure 11.7

Each phage particle is assembled by convergence of three pathways involving head, tail, and tail fibers. Figure 11.8

Figure 11.6 Replicative Cycle of Bacteriophage T4