Bacteriophage Sf6 and TSP
Sf6 is a temperate bacteriophage of Shigella flexneri and infects Y (and X) serotype strains. The receptor for Sf6 is the lipopolysaccharide (LPS) O antigen. The sequence of the Sf6 genome has been determined. Sf6 lysogeny results in serotype conversion (Y to 3b). The Sf6 oac gene encodes an acetyl transferase that modifies the Y serotype O antigen.
Adsoption to the O antigen is mediated by the tail spike proteins (TSPs). TSP also has endorhamnosidase activity and is able to hydrolyse the LPS O antigen chains from >100 repeat units down to 4-6 repeat units. TSP is useful in studying O antigen and the cell surface molecules of S. flexneri.
Casjeans, S., Winn-Stapley, D.A., Gilcrease, E., Morona, R., Kühlewein, C., Chua, J.E.H., Manning., P.A., Inwood., W., and Clark., A.J. (2004) "The chromosome of Shigella flexneri bacteriophage Sf6: complete nucleotide sequence, genetic mosaicism, and DNA packaging." J. Mol. Biol. 339: 379-394.
Morona, R., and Van Den Bosch, L. (2003) "Lipopolysaccharide O antigen chains mask IcsA(VirG) in Shigella flexneri" FEMS Microbiol. Lett. 221: 173-180.
Freiberg, A., Morona, R., Van Den Bosch, L., Jung, C., Behlke, J., Carlin, N, Seckler, R., and Baxa, U. (2003) “The tailspike protein of Shigella phage Sf6: A structural homolog of Salmonella phage P22 tailspike without sequence similarity in the b-helix domain.” J. Biol. Chem. 278: 1542-1548
Chua, J. E.H., Manning, P.A., and Morona, R. (1999) The Shigella flexneri bacteriophage Sf6 tailspike protein (TSP)/endorhamnosidase is related to the bacteriophage P22 TSP and has a motif common to exo- and endoglycanases, and C-5 epimerases. Microbiol. 145: 1649-1659.
SfII is a temperate bacteriophage of S. flexneri, and lysogeny with SfII results in serotype conversion. SfII encoded gtrII gene activity results in Y serotype LPS O antigen being modified by glucosylation, and the O antigen produced by lysogens has the 2a serotype.
George, D.T., Stephenson, D.P., Tran, E., Morona, R., and Verma, N.K. (2013) Complete genome sequence of SfII, a serotype-converting bacteriophage of the highly prevalent Shigella flexneri serotype 2a. Genome Announc. 2013 Sep 12;1(5). pii: e00626-13. doi: 10.1128/genomeA.00626-13.
Mavris, M., Manning, P.A., and Morona, R. (1997) “Mechanism of bacteriophage SfII mediated serotype conversion in Shigella flexneri”. Mol. Microbiol. 26: 939-950.
Korres, H., Mavris, M., Morona, R., Manning, P.A., and Verma, N. (2005) "Topological analysis of GtrA and GtrB proteins encoded by the serotype-converting cassette of Shigella flexneri." Biochem. Biophys. Res. Comm. 328: 1252-1260.