FIGURE 4.

Putative catalytic residues of Wzy in F. tularensis LVS. A, ClustalW analysis based on the bacteria present in the same phylogeny. C.S, Chromohalobacter salexigens DSM 3043; H.H, Halorhodospira halophila SL1; M.sp, Marinobacter sp. ELB17; N.M, Nitrococcus mobilis Nb-231; P. AR, Psychrobacter arcticus 273-4; P. AT, Pseudoalteromonas atlantica T6c; S.D, Saccharophagus degradans 2–40; T.C, Thiomicrospira crunogena XCL-2; F.T, Francisella tularensis LVS. B, topology of the O-antigen polymerase in F. tularensis LVS based on TMHMM-2.0 and the previously published topology map of Shigella (33). C, immunoblot of wzy mutants harboring plasmids containing site-specific amino acid substitutions in Wzy. Alanine substitutions on the charged amino acids in the periplasmic loop of Wzy (a), mutation of the Gly³²³, Asp¹⁷⁷ and their adjacent residues (b).