This entry represents the C-terminal beta sandwich domain found in the muzzle protein found at the distal end of the tail in bacteriophages of the Crassviridae family. This large protein forms a hexameric assembly at the tip of the tail barrel and ex ...
This entry represents the C-terminal beta sandwich domain found in the muzzle protein found at the distal end of the tail in bacteriophages of the Crassviridae family. This large protein forms a hexameric assembly at the tip of the tail barrel and exhibits a novel fold designated as the crass fold. The muzzle protein is composed of five domains: a ring-joining domain, a seven-bladed beta-propeller domain, two immunoglobulin-like domains (IG1 and IG2), and the crass domain. The muzzle protein forms a gate-like structure that likely serves as a gatekeeper controlling the ejection of cargo proteins and viral DNA during infection. The gate is formed by a loop within blade 4 of the propeller domain. The crass domain, with its exposed surface loops, likely plays a role in contacting the host cell surface, initiating conformational changes that open the gate. The muzzle protein is highly conserved among crassviruses, though with length variations resulting from insertions in the crass and IG2 domains that affect surface properties. This protein has been structurally characterized in Bacteroides phage crAss001 [1].
