Figure 3.

Cleavage sites in head proteins of φKZ and their conservation in related phages. Cleavage motifs in (A) the φKZ major head protein, gp120 and (B) φKZ abundant head protein, gp93. Red arrows indicate cleavage sites identified by MS; purple arrows indicate potential cleavage sites that adhere to the cleavage motif, see Figure 4. Blue circles indicate sequences that adhere to the processing motif but are not cleaved. (C) Conservation of cleavage motifs in proteins homologous to processed φKZ proteins. KZ, refers to φKZ, 2-1 refers to 201 φ2-1, and PA3 refers to φPA3. Red underlined residues are identified cleavage sites in φKZ proteins and in (vi) 201 φ2-1 (Thomas et al., 2010). Conserved residues in other phage proteins are also red. Comparison of processing sites in homologs to the φKZ (i) major capsid protein, gp120 (ii) protease, gp175, (iii) gp84, (iv) gp92, (v) gp120 (maturation cleavage), (vi) gp162, and (vii) portal protein, gp129. (D) Conservation of processing motifs in proteins homologous to processed T4 proteins. 44RR refers to 44RRt.8. Red underlined residues are known processing sites in T4 proteins (Black et al., 1993). Conserved residues, representing putative processing sites in homologous proteins are also red. Putative processing motifs in homologs to the T4 processed protein that are not strictly conserved are in bold. Comparison of processing sites in T4 (i) and (ii) major capsid protein, gp23, and (iii) major scaffold protein, gp22 are to their homologs.