The surface O-antigen polymers of gram-negative bacteria exhibit a modal length distribution that depends on dedicated chain-length regulator periplasmic proteins (Polysaccharide Co-Polymerases, PCPs) anchored in the inner membrane by two transmembrane helices. In an attempt to determine whether structural changes underlie the O-antigen modal length specification we have determined crystal structures of several closely related PCPs, namely two chimeric PCP-1 family members solved at 1.5A and 2.6A and a wild-type PCP-1 from Shigella flexneri solved at 2.8A. The chimeric proteins form circular octamers while the wild type WzzB from Shigella flexneri was found to be an open trimer. We also present the structure of a WzzBFepE mutant, which exhibits severe attenuation in its ability to produce very long O-antigen polymers. Our findings suggest that the differences in the modal length distribution depend primarily on the surface-exposed amino acids in specific regions rather than on the differences in the oligomeric state of the PCP protomers.
Structural characterization of closely related o-antigen LPS-chain length regulators.,Kalynych S, Yao D, Magee J, Cygler M J Biol Chem. 2012 Mar 21. PMID:22437828[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
↑ Kalynych S, Yao D, Magee J, Cygler M. Structural characterization of closely related o-antigen LPS-chain length regulators. J Biol Chem. 2012 Mar 21. PMID:22437828 doi:10.1074/jbc.M112.354837
