Life cycles of λ Bacteriophage; Regulation of Lytic and Lysogenic cycle
Life cycles of λ Bacteriophage; Regulation of Lytic and Lysogenic cycle
- The lambda phage (family Siphoviridae), that uses K12 strain of E. coli as its host is the best-understood temperate phage.
- Lambda is a double-stranded DNA (48.5 kb) phage with an icosahedral head (55 nm diameter) and a long, noncontractile tail (175 nm) with a thin tail fiber at its end.
- The genome is a linear DNA molecule with complementary cohesive ends (12 nt) which help the linear genome to circularize immediately upon infection
- Over 40 genes have been mapped on lambda phage chromosome, which are clustered according to their function with separate groups involved in lysogeny and its regulation, DNA replication, head synthesis, tail synthesis and cell lysis.
- During infection, phage λ binds to the maltose receptor on surface of a bacterium and inject its genetic material into the bacterial cytoplasm.
- The phage will then proceed along only one of two alternative life cycles
- Lytic cycle
- Lysogenic cycle
