FIG 5 .

The gene cluster BT3362 to BT3380 is responsible for the biosynthesis of the B. thetaiotaomicron LOS oligosaccharide region. (A) Schematic of the gene cluster BT3362 to BT3380, which includes genes predicted to encode 13 glycosyltransferases shown in red, those for an LPS kinase shown in yellow, those for four tailoring enzymes shown in blue, and one for a putative GtrA-like protein shown in magenta. (B) LOS was isolated from the eight B. thetaiotaomicron transposon mutants, the B. thetaiotaomicron Δtdk strain, and the B. thetaiotaomicron ΔCPS strain by the microscale extraction method, and the resulting material was run on a 16% Tricine SDS-PAGE gel. The transposon mutants are labeled “tn” followed by the locus tag of the gene in which the transposon has inserted. For example, “tnBT3365” indicates a B. thetaiotaomicron strain with a transposon inserted in BT3365. All transposon mutants are in the wild-type Bacteroides thetaiotaomicron VPI 5482 background with the tdk gene present and are erythromycin resistant. The LOS migrates on the gel differently for almost all of the transposon mutants compared to B. thetaiotaomicron Δtdk and B. thetaiotaomicron ΔCPS strains; only the B. thetaiotaomicron tnBT3380 mutant, with the transposon inserted in the last gene in the cluster, has the same banding pattern on the gel as the two strains with wild-type LOS. The band at the top of the gel is CPS, which is present in all of the transposon mutants and the B. thetaiotaomicron Δtdk strain but not the B. thetaiotaomicron ΔCPS strain.