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Baseplate wedge protein gp25 This family represents T4 phage gp25 protein and gp25-like proteins, found in several systems, including contractile tail bacteriophages, the type VI secretion system (T6SS) and R-type pyocins, which constitute a multiprotein tubular apparatus to attach to and penetrate host cell membranes. Gp25 is a component of the conserved wedge in the inner part of the baseplate and serves as a nucleus for sheath polymerization, playing a critical role in sheath assembly and contraction. The EPR motif (Glu-Pro-Arg, residues 85-87 of gp25) is conserved across all members of the family including orthologs from the RpoS-mediated general stress response system (called IraD). This motif interacts with the 'core bundle' composed of orthologs of T4 gp6 and gp7 proteins in contractile injection systems. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",