Přehled o publikaci

Pseudomonas phage LUZ19 exhibits broad infectivity across clinically relevant P. aeruginosa strains. Phage assembly starts from a dodecameric portal complex attached to the host cell membrane. The construction of the capsid shell around the portal is facilitated by scaffold proteins which create a mesh structure located inside the completed immature procapsid. The scaffolding is cleaved and discarded during the genome filling and the accompanying procapsid expansion. To understand how the scaffold protein of LUZ19, with roughly half of its residues predicted in disordered linkers, establishes the icosahedral shape of the phage capsid and mediates the symmetry mismatch between the capsid and the portal vertex, we conducted a cryo-EM study of the immature LUZ19 phage particle. We show that the immature procapsid is 16% smaller and exhibits a rougher surface compared to the expanded capsid. The particle contains scaffold and inner core proteins alongside portal and capsid proteins. The inner core complex forms a tower structure inside the capsid, composed of three types of proteins stacked over the portal complex. Interestingly, the portal complex is not in direct contact with capsid proteins; instead, C C-terminal αα-helical domains of scaffold proteins bridge the interaction. Our ongoing research aims to elucidate the intricate interactions between scaffold proteins within the mesh, with particular focus on the functional role of their long, disordered NN-termini.