A NEW GLYCOSYLATED LIPOPEPTIDE INCORPORATED INTO THE CELL-WALL OF A SMOOTH VARIANT OF GORDONA-HYDROPHOBICA

A cell wall component of a smooth variant of Gordona hydrophobica 1775 /15 was isolated and purified, and its structure was determined by var ious chemical methods, including chemical synthesis of part structures , Edman degradation, gas chromatography/mass spectrometry analysis, ma trix-assisted laser desorption ionization-post-source decay (MALDI-PSD ) tandem mass spectrometry, and H-1 and C-13 NMR using one- and two-di mensional, homo- and heteronuclear correlated spectroscopy. The cell w all component was found to be a (mono-) glycosylated peptidolipid (GPL ) consisting of a tridecapeptide interlinked by a beta-hydroxylated fa tty acid (3-hydroxyeicosanoic acid, 20:0 (3-OH) to form a cyclic lacto ne ring structure. The main fraction of GPL, for which we propose the name gordonin, was identified as ucyl-L-valyl-L-seryl-L-phenylalanyl-g lycyl-L-valyl lactone. The other GPLs constitute structural variations within the nature of the beta-hydroxylated fatty acid (20:0(3-OH) ver sus 22:1(3-OH)) in a ratio of about 1:0.9 as well as within one amino acid (D-Leu versus L-Phe) in about 30%. Sequence information was obtai ned in part by Edman degradation as well as gas chromatography/mass sp ectrometry analysis of di- and tripeptide fragments. However, the comp lete amino acid sequence could only be established by MALDI-PSD from t he linear molecule, i.e. after ring opening of the lactone. In contras t, rough variants of G. hydrophobica 1775/15 lack these peptidolipids or synthesize them to a much lesser extent indicating that gordonin co ntributes significantly to the physicochemical character of the cell s urface.