Fig 1.

Proposed activation and transfer pathway of the last hexose residue of the N-glycan in S. acidocaldarius. (A) Proposed biosynthesis and transferase pathway of the last hexose. The structure of the unidentified hexose is shown as glucose. saci0802 encodes a proposed 3-hexulose-6-phosphate synthase; saci0806 is annotated as a phosphoglucomutase, and agl16 codes for a soluble glycosyltransferase. Glycan symbols: blue sphere, glucose; green sphere, mannose; orange sphere, sulfoquinovose; blue square, GlcNAc. (B) Physical map of the gene region of S. acidocaldarius, where the gene coding for the glycosyltransferase Agl16 is located. The illustrated region encompasses saci0802 to saci0808. The outlined gene encodes the glycosyltransferase Agl16. The genes saci0802 and saci0806 are most likely also involved in the activation of the hexose.