Modification of lipopolysaccharide with colanic acid (M-antigen) repeats in Escherichia coli

Timothy C. Meredith, Uwe Mamat, Zbigniew Kaczynski, Buko Lindner, Otto Holst, Ronald W. Woodard*

*Corresponding author for this work
52 Citations (Scopus)


Colanic acid (CA) or M-antigen is an exopolysaccharide produced by many enterobacteria, including the majority of Escherichia coli strains. Unlike other capsular polysaccharides, which have a close association with the bacterial surface, CA forms a loosely associated saccharide mesh that coats the bacteria, often within biofilms. Herein we show that a highly mucoid strain of E. coli K-12 ligates CA repeats to a significant proportion of lipopolysaccharide (LPS) core acceptor molecules, forming the novel LPS glycoform we call M LPS. MLPS biosynthesis is dependent upon (i) CA induction, (ii) LPS core biosynthesis, and (iii) the O-antigen ligase WaaL. Compositional analysis, mass spectrometry, and nuclear magnetic resonance spectroscopy of a purified MLPS sample confirmed the presence of a CA repeat unit identical in carbohydrate sequence, but differing at multiple positions in anomeric configuration and linkage, from published structures of extracellular CA. The attachment point was identified as O-7 of the L-glycero-D-manno-heptose of the outer LPS core, the same position used for O-antigen ligation. When O-antigen biosynthesis was restored in the K-12 background and grown under conditions meeting the above specifications, only MLPS was observed, suggesting E. coli can reversibly change its proximal covalently linked cell surface polysaccharide coat from O-antigen to CA in response to certain environmental stimuli. The identification of MLPS has implications for potential underlying mechanisms coordinating the synthesis of various surface polysaccharides.

Original languageEnglish
JournalJournal of Biological Chemistry
Issue number11
Pages (from-to)7790-7798
Number of pages9
Publication statusPublished - 16.03.2007
Externally publishedYes

Research Areas and Centers

  • Academic Focus: Center for Infection and Inflammation Research (ZIEL)


Dive into the research topics of 'Modification of lipopolysaccharide with colanic acid (M-antigen) repeats in Escherichia coli'. Together they form a unique fingerprint.

Cite this