Structure of bacteriophage T4 gene product 11, the interface between the baseplate and short tail fibers

Bacteriophage T4, like all other viruses, is required to be stable while be ing transmitted from host to host, but also is poised to eject efficiently and rapidly its double-stranded DNA genome to initiate infection. The latte r is coordinated by the recognition of receptors on Escherichia coil cells by the long tail fibers and subsequent irreversible attachment by the short tail fibers. These fibers are attached to the baseplate, a multi-subunit a ssembly at the distal end of the tail. Recognition and attachment induce a conformational transition of the baseplate from a hexagonal to a star-shape d structure. The crystal structure of gene product 11 (gp11), a protein that connects th e short tail fibers to the baseplate, has been determined to 2.0 Angstrom r esolution using multiple wavelength anomalous dispersion with Se. This stru cture is compared to the trimeric structure of gp9, which connects the base plate with the long tail fibers. The structure of gp11 is a trimer with eac h monomer consisting of 218 residues folded into three domains. The N-termi nal domains form a central, trimeric, parallel coiled coil surrounded by th e middle "finger" domains. The fingers emanate from the carboxy-terminal be ta-annulus domain, which, by comparison with the T4 whisker "fibritin" prot ein, is probably responsible for trimerization. The events leading from rec ognition of the host to the ejection of viral DNA must be communicated alon g the assembled trimeric (gp9)(3) attached to the long tail fibers via the trimeric baseplate protein (gp10)(3) to the trimeric (gp11)(3) and the trim eric short tail fibers. (C) 2000 Academic Press.