Structural analysis of a new glycosphingolipid from the lipopolysaccharide-lacking bacterium Sphingomonas adhaesiva

A new glycosphingolipid, GSL-4B, was isolated from Sphingomonas adhaesiva and found to share the ceramide moiety with GSL-1 and GSL-3 from Sphingomonas capsulata studied earlier [Kawahara, K.; Moll, H.; Knirel, Y. A.; Seydel, U.; Zähringer, U. Eur. J. Biochem. 2000, 267, 1837–1846]. It is heterogeneous with respect to the long-chain bases erythro-2-amino-1,3-octadecanediol (sphinganine), (13Z)-erythro-2-amino-13-eicosene-1,3-diol, and (13Z)-erythro-2-amino-13,14-methylene-1,3-eicosanediol which in GSL-4B are present in the ratios of 1.1:1.0:1.1, and all bearing amide-linked (S)-2-hydroxymyristic acid. Methylation analysis and MALDI-TOF–MS along with 1H and 13C NMR spectroscopy showed that the carbohydrate part of GSL-4B has the structure ofα-d-Glcp-(1→4)-α-d-Galp-(1→6)-α-d-Glcp-(1→4)-α-d-GlcpA-(1→1)-Cer