Journal of the American Chemical Society, Vol.133, No.34, 13571-13576, 2011
Screw Motion Regulates Multiple Functions of T4 Phage Protein Gene Product 5 during Cell Puncturing
Bacteriophage T4 penetrates the outer membrane of Escherichia coil using a multifunctional device composed of a gene product 5 (gp5) protein trimer. We report that gp5 sequentially exerts distinct Functions along the course of penetration stages induced by screw motion. A triple-stranded beta-helix of gp5 acts as a cell-puncturing drill bit to make a hole on the membrane and then send the lipids upward efficiently by strong charge interactions. The gp5 lysozyme domains, which degrade the peptidoglycan layer later, are shown to play novel roles to enlarge the hole and control the release of the beta-helix. The lysozyme active site is protected from lipid binding during the penetration and is exposed after the beta-helix release. Intrinsic multiple functions of gp5 are shown to be served in turn regulated by gradual change of interdomain interactions, which enables the initial infection process with single protein trimer by continuous screw motion. The results of lysozyme domain should be understood as the case where a single-function protein acquired multiple chemical functions through interplay with other domains in a multidomain protein.