Details

Autor(en) / Beteiligte

• Doyle, Liam
• Ovchinnikova, Olga G
• Myler, Katharine
• Mallette, Evan
• Huang, Bo-Shun
• Lowary, Todd L
• Kimber, Matthew S
• Whitfield, Chris

Titel

Biosynthesis of a conserved glycolipid anchor for Gram-negative bacterial capsules

Ist Teil von

• Nature chemical biology, 2019-06, Vol.15 (6), p.632

Ort / Verlag

United States

Erscheinungsjahr

2019

Quelle

MEDLINE

Beschreibungen/Notizen

• Several important Gram-negative bacterial pathogens possess surface capsular layers composed of hypervariable long-chain polysaccharides linked via a conserved 3-deoxy-β-D-manno-oct-2-ulosonic acid (β-Kdo) oligosaccharide to a phosphatidylglycerol residue. The pathway for synthesis of the terminal glycolipid was elucidated by determining the structures of reaction intermediates. In Escherichia coli, KpsS transfers a single Kdo residue to phosphatidylglycerol; this primer is extended using a single enzyme (KpsC), possessing two cytidine 5'-monophosphate (CMP)-Kdo-dependent glycosyltransferase catalytic centers with different linkage specificities. The structure of the N-terminal β-(2→4) Kdo transferase from KpsC reveals two α/β domains, supplemented by several helices. The N-terminal Rossmann-like domain, typically responsible for acceptor binding, is severely reduced in size compared with canonical GT-B folds in glycosyltransferases. The similar structure of the C-terminal β-(2→7) Kdo transferase indicates a past gene duplication event. Both Kdo transferases have a narrow active site tunnel, lined with key residues shared with GT99 β-Kdo transferases. This enzyme provides the prototype for the GT107 family.