The O18 antigens (lipopolysaccharides) of Escherichia coli

Abstract

The 0-specific polysaccharide moieties (PS) of the 018A, 018A1, 018B, and 018B1 antigens (lipopolysaccharides, LPS) consist of L-rhamnose (Rhd), N-aCetyl-D-glUCOSamine, D-galaCtOSe, and D-glucose in different molar ratios. By using chemical fragmentation, methylation, as well as oneand two-dimensional NMR spectroscopy, the structures of these polysaccharides were found to beIn 018A-PS and 018A1-PS x = 2, whereas in 018B-PS and in 018B11-PS x = 3. In all fourGlcpNAc-(1 in 018A-PS and 018A1-PS and it is a-~-Glcp-(l in 018B-PS and 018B1-PS. Whereas there is no further substituent on the main chain of the 018A and 018B polysaccharides, in 018A1-PS and 018B1-PS the E-D-GIc~NAc residue A is substituted with a-Glcp-(1 (residue F), which is linked to 0 -6 in 018A1-PS and to 0 -4 in 018B1-PS. These results show that the 018 antigen comprises a group of four related LPS (018A and OIXB, with their glucosylated forms 018A1 and 01 SBl). The results are discussed with respect to epitope definition and biochemical implications.The serological classification of Escherichiu coli is based on their 0 antigens (lipopolysaccharides, LPS), K antigens (capsular polysaccharides), H antigens (flagellar proteins) [I -31 and, more recently also on their F antigens (fimbrial and fibrillar proteins) [4]. Additionally, such distinctive characteristics as biotype or isoenzyme pattern as detected by starch gel electrophoresis [5] are in use. In a clonal analysis of E. coli, strains with 0 antigens prevalent in extraintestinal infections, emphasis was put on the migration patterns of the major outer membrane proteins in sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS/PAGE) [6]. In these and subsequent studies 17-91, it became apparent that many strains, even when belonging to different E. coli clones, were of the same 0 group. This was particularly evident with E. coli expressing the 0 1 or the 018 antigen. On the basis of their migration patterns in SDS/PAGE, the 01 antigens were divided into three groups (OIA, 01B and OlC). Of these, the 0 1 A antigen seemed to be clonally restricted, whereas no clonality of the 0 1 B and 0 1 C (only one strain known) was detected with the same method. The 018 antigens which had been serologically classified into 018ac and 018ab [lo] were subdivided into Abbreviations. 2D COSY, two-dimensional correlated NMR spectroscopy; LPS, lipopolysaccharide; PS, polysaccharide moiety of lipopolysaccharide; TOE, truncated driven mode of nuclear Overhauser effect (NOE) NMR experiment; Rha, rhamnose. four groups 171. They were termed 018A and 018A1 (formerly 018ac) and 018B and 018B1 (formerly 018ab).Serological studies showed that the 018 antigens shared (at least) one epitope and were otherwise distinct.To establish a molecular basis for the observed 0 antigen differences, we have set out to elucidate the structures of the respective LPS. Recently, we reported the structures of the 01A, 01B and 01C LPS [ll, lla]. In an earlier report we presented the structure of the 018ac LPS [12], which is now defined as...

Crystal structure of Escherichia coli phage HK620 tailspike: podoviral tailspike endoglycosidase modules are evolutionarily related

“…B. Structure of the hexasaccharide repeat of O18A1‐type O‐antigen (Jann et al. , 1992) that is produced and bound by HK620 TSPΔN.…”

“…, 1986). The O‐specific polysaccharide of O18 is composed of l ‐rhamnose, N ‐acetyl‐ d ‐glucosamin, d ‐galactose and d ‐glucose in varying linkages and molar ratios (Jann et al. , 1992).…”

“…, 1992). The hexasaccharide found in the crystal structure corresponds to one O‐antigen repeat of the serological subgroup O18A1 (Jann et al. , 1992).…”

“…However, the analysis did not distinguish between the specific epitopes of the serological subgroups O18A, O18A1, O18B and O18B1 (Pluschke et al, 1986). The O-specific polysaccharide of O18 is composed of L-rhamnose, N-acetyl-D-glucosamin, D-galactose and D-glucose in varying linkages and molar ratios (Jann et al, 1992). The hexasaccharide found in the crystal structure corresponds to one O-antigen repeat of the serological subgroup O18A1 (Jann et al, 1992).…”

NMR Chemical Shift Prediction of Glycans: Application of the Computer Program CASPER in Structural Analysis

“…5 . The determined O-antigen structure is identical to that from E. coli O18B [ 34 ]. The CASPER input for the above can be fi lled in automatically by going to http://tinyurl.com/d7zn524 .…”