Fig. 1. Structure of the A. aeolicus O antigen.

a Representative SDS-PAGE of A. aeolicus VF5 LPS. Lane 1: Salmonella enterica LPS; Lane 2: A. aeolicus VF5 LPS. In lane 1, the LPS band with the smallest molecular weight is the lipid A-core (*). The subsequent bands above the lipid A-core is lipid A-core with one repeat unit consecutively added after each band. An uncropped gel image is shown as Source Data. b Size exclusion of purified O antigen. The polysaccharide elutes at the first peak with an average molecular weight of 13.4 kDa. c Partial ¹H and ¹H,¹³C-HSQC spectra of the released HMW O polysaccharide chain with signal assignments. Anomeric peak areas are shown below the ¹H spectrum. The two insets of HSQC spectrum at lower contour levels show the anomeric and methyl group signals of the terminal residues F and G. The signals of rhamnose methyl groups (B6, C6 and D6) are aliased along F1 and their actual ¹³C chemical shifts are lower by 70 ppm. d Structural motifs present in A. aeolicus LPS O antigen. The partial structures illustrate the origin of the a/b non-equivalency in the major residues A, B, C and D. No regular repeating unit could be determined, so a semi-regular repeating structure is proposed.