Přehled o publikaci

PhiKZ is a jumbo Pseudomonas aeruginosa. that infects the opportunistic human pathogen Pseudomonas aeruginosa. Its large genome and virion architecture make it a compelling subject for structural studies. Among its components, the baseplate is the most intricate, serving as the hub for host recognition and genome ejection. Using cryo-electron microscopy, we resolved the structure of the phiKZ tail and the baseplate core at high resolution. This represents the first high-resolution reconstruction of a jumbo phage baseplate. Our reconstruction reveals a sophisticated assembly of 15 proteins arranged with six-fold and three-fold symmetry, with stoichiometries ranging from 6 to 24 copies. Several baseplate proteins adopt novel structures, particularly those located in the distal regions of the baseplate core. The baseplate periphery, likely due to its intrinsic flexibility, was resolved at lower resolution, allowing only visualisation of its overall architecture. In this region, the baseplate features six outward-projecting arms linked to a peripheral ring, which is anchored to the tail tube by six arches. Due to the low synteny of the phiKZ genome, protein identification remains challenging. The sheer complexity of the baseplate reflects the elaborate virion assembly of phiKZ, underscoring the need for continued structural and functional characterisation.