This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Biosynthesis → Fatty Acids and Lipids Biosynthesis|
Some taxa known to possess this pathway include : Escherichia coli K-12 substr. MG1655
Expected Taxonomic Range: Proteobacteria
Bacterial lipopolysaccharides (LPS) typically consist of a hydrophobic domain inserted into the outer membrane known as lipid A (or endotoxin), a phosphorylated "core" oligosaccharide and a distal polysaccharide (or O antigen). The core oligosaccharides are conceptually divided into two regions: inner core and outer core. The inner core is highly conserved, comprises three deoxy-D-manno-octulosonic acid (KDO) and L-glycero-D-manno-heptose (Hep) and is often phosphorylated. The inner core oligosaccharide plays a critical role in essential barrier function of the outer membrane. The outer core comprises a tri-hexose backbone modified with varying side-branch substitutions of hexose and acetamidohexose residues. The outer core provides an attachment site for O-antigen. Strains of Escherichia coli K12 normally do not make O-antigen, unless a mutation in the O-antigen operon is corrected [Stevenson94].
About This Pathway
The completed lipid A-KDO2 serves as the acceptor on which the core oligosaccharide chains are assembled by sequential glycosyl transfer from nucleotide sugar precursors. This process involves a co-ordinated complex of membrane-associated glycosyltransferases acting at the cytoplasmic face of the plasma membrane. Many of the enzymes are predicted to be peripheral proteins.
Escherichia coli mutants that lack the heptose region of the inner core display "deep rough" phenotypes and causes instability of the outer membrane. These mutants lose expression of pili and flagella and secrete hemolysin with reduced activity. Mutations that eliminate synthesis of the outer core result in enhanced susceptibility to some hydrophobic compouns due to an indirect effect on core phosphorylation.
Superpathways: superpathway of lipopolysaccharide biosynthesis
Unification Links: EcoCyc:LIPA-CORESYN-PWY
Heinrichs98: Heinrichs DE, Yethon JA, Whitfield C (1998). "Molecular basis for structural diversity in the core regions of the lipopolysaccharides of Escherichia coli and Salmonella enterica." Mol Microbiol 30(2);221-32. PMID: 9791168
Stevenson94: Stevenson G, Neal B, Liu D, Hobbs M, Packer NH, Batley M, Redmond JW, Lindquist L, Reeves P (1994). "Structure of the O antigen of Escherichia coli K-12 and the sequence of its rfb gene cluster." J Bacteriol 1994;176(13);4144-56. PMID: 7517391
Agladze05: Agladze K, Wang X, Romeo T (2005). "Spatial periodicity of Escherichia coli K-12 biofilm microstructure initiates during a reversible, polar attachment phase of development and requires the polysaccharide adhesin PGA." J Bacteriol 187(24);8237-46. PMID: 16321928
Austin90: Austin EA, Graves JF, Hite LA, Parker CT, Schnaitman CA (1990). "Genetic analysis of lipopolysaccharide core biosynthesis by Escherichia coli K-12: insertion mutagenesis of the rfa locus." J Bacteriol 172(9);5312-25. PMID: 2168379
Brabetz97: Brabetz W, Muller-Loennies S, Holst O, Brade H (1997). "Deletion of the heptosyltransferase genes rfaC and rfaF in Escherichia coli K-12 results in an Re-type lipopolysaccharide with a high degree of 2-aminoethanol phosphate substitution." Eur J Biochem 247(2);716-24. PMID: 9266718
CarlsonBanning13: Carlson-Banning KM, Chou A, Liu Z, Hamill RJ, Song Y, Zechiedrich L (2013). "Toward repurposing ciclopirox as an antibiotic against drug-resistant Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae." PLoS One 8(7);e69646. PMID: 23936064
Chen93b: Chen L, Coleman WG (1993). "Cloning and characterization of the Escherichia coli K-12 rfa-2 (rfaC) gene, a gene required for lipopolysaccharide inner core synthesis." J Bacteriol 175(9);2534-40. PMID: 8478319
Creeger79: Creeger ES, Rothfield LI (1979). "Cloning of genes for bacterial glycosyltransferases. I. Selection of hybrid plasmids carrying genes for two glucosyltransferases." J Biol Chem 254(3);804-10. PMID: 368061
Czyzyk11: Czyzyk DJ, Liu C, Taylor EA (2011). "Lipopolysaccharide biosynthesis without the lipids: recognition promiscuity of Escherichia coli heptosyltransferase I." Biochemistry 50(49);10570-2. PMID: 22059588
DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114
Genevaux99: Genevaux P, Bauda P, DuBow MS, Oudega B (1999). "Identification of Tn10 insertions in the rfaG, rfaP, and galU genes involved in lipopolysaccharide core biosynthesis that affect Escherichia coli adhesion." Arch Microbiol 172(1);1-8. PMID: 10398745
Grizot06: Grizot S, Salem M, Vongsouthi V, Durand L, Moreau F, Dohi H, Vincent S, Escaich S, Ducruix A (2006). "Structure of the Escherichia coli heptosyltransferase WaaC: binary complexes with ADP and ADP-2-deoxy-2-fluoro heptose." J Mol Biol 363(2);383-94. PMID: 16963083
Gronow00: Gronow S, Brabetz W, Brade H (2000). "Comparative functional characterization in vitro of heptosyltransferase I (WaaC) and II (WaaF) from Escherichia coli." Eur J Biochem 267(22);6602-11. PMID: 11054112
Gronow09: Gronow S, Lindner B, Brade H, Muller-Loennies S (2009). "Kdo-(2 --> 8)-Kdo-(2 --> 4)-Kdo but not Kdo-(2 --> 4)-Kdo-(2 --> 4)-Kdo is an acceptor for transfer of L-glycero-alpha-D-manno-heptose by Escherichia coli heptosyltransferase I (WaaC)." Innate Immun 15(1);13-23. PMID: 19201821
Ilg10: Ilg K, Yavuz E, Maffioli C, Priem B, Aebi M (2010). "Glycomimicry: display of the GM3 sugar epitope on Escherichia coli and Salmonella enterica sv Typhimurium." Glycobiology 20(10);1289-97. PMID: 20574043
Kadrmas96: Kadrmas JL, Brozek KA, Raetz CR (1996). "Lipopolysaccharide core glycosylation in Rhizobium leguminosarum. An unusual mannosyl transferase resembling the heptosyl transferase I of Escherichia coli." J Biol Chem 271(50);32119-25. PMID: 8943265
Kadrmas98: Kadrmas JL, Raetz CR (1998). "Enzymatic synthesis of lipopolysaccharide in Escherichia coli. Purification and properties of heptosyltransferase i." J Biol Chem 273(5);2799-807. PMID: 9446588
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