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Lipopolysaccharide (LPS) molecules are located in the outer leaflet of the outer membrane of bacteria such as Shigella flexneri and Salmonella enterica Typhimurium. LPS molecules are amphipathic and have three regions: lipid A, core sugars, and O antigen polysaccharides. The O antigen polysaccharides of S. flexneri and S. Typhimurium are composed of repeats of a tetrasaccharide unit, and range from 1 to >100 repeat units in length. The length of O antigen polysaccharides is regulated by the activity of Wzz proteins, with different Wzz proteins able to confer different modal length distributions. O antigen polysaccharide chain length impacts on virulence as it affects resistance to Complement, and actin based motility.

Relevant Publications

Kalynych, S., Morona, R., and Miroslaw, C. (2014) Progress in understanding the assembly process of bacterial O-Antigen. FEMS Microbiol Rev. 2014 Mar 11. doi: 10.1111/1574-6976.12070. [Epub ahead of print]

Tran, E.N.H. and Morona R. (2013) Residues located inside the Escherichia coli FepE protein oligomer are essential for lipopolysaccharide O-antigen modal chain length regulation. Microbiology (SGM). 159: 701-714.

Papadopoulos, M and Morona, R. (2010) Mutagenesis and chemical cross-linking suggest that Wzz dimer stability and oligomerization affect lipopolysaccharide O-antigen modal chain length control. J. Bacteriol. 192: 3385-3393.

Morona, R., Purins, L., Tocilj, A., Matte, A., and Cygler M. (2009) Sequence-structure relationships in polysaccharide co-polymerase (PCP) proteins. Trends Biochem Sci. 34:78-84.

Purins, L., Van Den Bosch, L., and Richardson, V., and Morona, R. (2008) Coiled-coil regions play a role in the function of the Shigella flexneri O-antigen chain length regulator WzzpHS2. Microbiology (SGM) 154:1104-1116.

Tocilj, A., Munger, C., Proteau, A., Morona, R., Purins, L., Ajamina, E., Wagner, J., Papadopoulos, M., Van Den Bosch, L., Rubinstein, J.L., Féthière, J., Matte, A., and Cygler, M. (2008) Bacterial polysaccharide co-polymerases share a common framework for control of polymer length. Nature Struct. Mol. Biol. 15:130-138.

Murray, G.L., Attridge, S.R., and Morona, R. (2006) Altering the length of Salmonella typhimurium lipopolysaccharide O antigen has an impact on interaction with macrophages and complement". J. Bacteriol. 188: 2735-2739.

Murray, G.L., Attridge, S.R., and Morona, R. (2005) "Inducible serum resistance in Salmonella typhimurium is dependent on wzz(fepE)-regulated very long O antigen chains". Microbes Infect. 7: 1296-1304.

Morona, R., Daniels, C., and Van Den Bosch, L. (2003) “Genetic modulation of Shigella flexneri 2a lipopolysaccharide O antigen modal chain length reveals that it has been optimised for virulence.” Microbiology, 49: 925-939.

Murray, G.L., Attridge, S.R., and Morona, R. (2003) “Regulation of Salmonella typhimurium lipopolysaccharide O antigen chain length is required for virulence; identification of FepE as a second Wzz.” Mol. Microbiol. 47: 1395-1406.

Morona, R., and Van Den Bosch, L. (2003) "Lipopolysaccharide O antigen chains mask IcsA(VirG) in Shigella flexneri" FEMS Microbiol. Lett. 221: 173-180.

Morona, R., Van Den Bosch, L., and Daniels, C. (2000) “Evaluation of Wzz/MPA1/MPA2 proteins based on the presence of coiled-coil regions.”  Microbiol. 146: 1-4.
Table for this paper.

Baker, S.J., Gunn, J.S. and Morona, R. (1999) “The Salmonella typhi melittin resistance gene pqaB affects intracellular growth in PMA-differentiated U937 cells, polymyxin B resistance, and lipopolysaccharide.” Microbiol. 145: 367-378.

Daniels, C., and Morona, R. (1999) Analysis of Shigella flexneri Wzz (Rol) function by mutagenesis and cross-linking: Wzz is able to oligomerise. Mol. Microbiol. 34: 181-194.

Daniels, C., Vindurampulle, C., and Morona, R. (1998) Overexpression and topology of the Shigella flexneri O-antigen polymerase (Rfc/Wzy). Mol. Microbiol. 28: 1211-1222.

Van Den Bosch, L., Manning, P.A., and Morona, R. (1997) “Regulation of O-antigen chain length is required for Shigella flexneri virulence”. Mol. Microbiol. 23: 765-775.

Invasive Bacterial Pathogens Laboratory

North Terrace Campus
Level 4, Molecular Life Sciences
The University of Adelaide
SA 5005


Renato Morona
T: +61 8 8313 4151
F: +61 8 8313 7532