Recombinant Bacillus phage phi29 Histone-like protein p6 (6)

Histone-like nucleoprotein that binds to the viral dsDNA and responsible for wrapping and compacting the viral DNA about 4-fold. Forms a nucleoprotein complex in which the DNA adopts a right-handed toroidal conformation winding around a protein core. Binds ito most, if not all, the viral genome, although with different affinity, the highest one corresponding to the genome ends. The formation of the nucleoprotein complex at the genome ends, activates the initiation of viral DNA replication. The binding of p6 would recruit the complex formed by the TP and the DNA polymerase to the origin. Protein p6 also represses early transcription from promoter C2, and, together with protein p4, represses transcription from promoters A2b and A2c and activates late transcription from promoter A3. Protein p6 is therefore involved in the early to late transcription switch. The formation of the nucleoprotein complex at the right end of the phage genome where the early promoter C2 is located affects local topology, which may contribute to the promoter repression.