TY - JOUR A1 - Müller, Jürgen J. A1 - Barbirz, Stefanie A1 - Heinle, Karolin A1 - Freiberg, Alexander A1 - Seckler, Robert A1 - Heinemann, Udo T1 - An intersubunit active site between supercoiled parallel beta helices in the trimeric tailspike endorhamnosidase of Shigella flexneri phage Sf6 N2 - Sf6 belongs to the Podoviridae family of temperate bacteriophages that infect gram-negative bacteria by insertion of their double-stranded DNA. They attach to their hosts specifically via their tailspike proteins. The 1.25 Å crystal structure of Shigella phage Sf6 tailspike protein (Sf6 TSP) reveals a conserved architecture with a central, right-handed ; helix. In the trimer of Sf6 TSP, the parallel ; helices form a left-handed, coiled;; coil with a pitch of 340 Å. The C-terminal domain consists of a ; sandwich reminiscent of viral capsid proteins. Further crystallographic and biochemical analyses show a Shigella cell wall O-antigen fragment to bind to an endorhamnosidase active site located between two ;-helix subunits each anchoring one catalytic carboxylate. The functionally and structurally related bacteriophage, P22 TSP, lacks sequence identity with Sf6 TSP and has its active sites on single subunits. Sf6 TSP may serve as an example for the evolution of different host specificities on a similar general architecture. Y1 - 2008 UR - http://www.cell.com/structure/abstract/S0969-2126%2808%2900106-8 U6 - https://doi.org/10.1016/j.str.2008.01.019 ER - TY - JOUR A1 - Barbirz, Stefanie A1 - Müller, Jürgen J. A1 - Uetrecht, Charlotte A1 - Clark, Alvin J. A1 - Heinemann, Udo A1 - Seckler, Robert T1 - Crystal structure of Escherichia coli phage HK620 tailspike : podoviral tailspike endoglycosidase modules are evolutionarily related N2 - Bacteriophage HK620 infects Escherichia coli H and is closely related to Shigella phage Sf6 and Salmonella phage P22. All three Podoviridae recognize and cleave their respective host cell receptor polysaccharide by homotrimeric tailspike proteins. The three proteins exhibit high sequence identity in the 110 residues of their N-terminal particle- binding domains, but no apparent sequence similarity in their major, receptor-binding parts. We have biochemically characterized the receptor-binding part of HK620 tailspike and determined its crystal structure to 1.38 Å resolution. Its major domain is a right-handed parallel ;-helix, as in Sf6 and P22 tailspikes. HK620 tailspike has endo-N- acetylglucosaminidase activity and produces hexasaccharides of an O18A1-type O-antigen. As indicated by the structure of a hexasaccharide complex determined at 1.6 Å resolution, the endoglycosidase-active sites are located intramolecularly, as in P22, and not between subunits, as in Sf6 tailspike. In contrast, the extreme C-terminal domain of HK620 tailspike forms a ;-sandwich, as in Sf6 and unlike P22 tailspike. Despite the different folds, structure-based sequence alignments of the C-termini reveal motifs conserved between the three proteins. We propose that the tailspike genes of P22, Sf6 and HK620 have a common precursor and are not mosaics of unrelated gene fragments. Y1 - 2008 UR - http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2958.2008.06311.x/pdf SN - 0950-382X ER -