The structure of syringomycins A₁, E and G

Abstract

By a combination of 1D and 2D 1H-and ~3C-NMR, FAB-MS, and chemical and enzymatic reactions carried out at the milligram level, it has been demonstrated that syringomycin E, the major phytotoxic antibiotic produced by Pseudomonas syringae pv. syringae, is a new lipodepsipcptide. Its amino acid sequence is Ser-Ser-Dab-Dab-Arg-Phe-Dhb-4(Cl)Thr-3(OH)Asp with the fl-carboxy group of the C-terminal residue closing a macrocyclic ring on the OH group of the N-terminal Scr, which in turn is N-acylated by 3-hydroxydodecanoic acid. Syringomycins A~ and G, two other metabolites of the same bacterium, differ from syringomycin E only in their fatty acid moieties corresponding, respectively, to 3-hydroxydecanoic and 3-hydroxytetradecanoic acid.

Novel bioactive lipodepsipeptides from Pseudomonas syringae: The pseudomycins

“…syringue pv. syringue [21]; (v) the third and the fourth residues with the L-configuration, while in their congeners either one or the other has the D-configuration [21]; (vi) the fifth residue correspondent to a basic L-amino acid residue (Dab), as found in syringomycins (Arg) [3,4], syringotoxin (Orn) [5,6], syringostatins (Orn) [7]. The occurrence of ~-Asp in the peptide moiety of the pseudomycins is a novel feature of the lipodepsinonapeptides which might affect their conformation and biological properties.…”

“…The aim of our research on pseudomycins was to complete the study of their structure and to investigate their biological properties. Four of them turned out to be new lipodepsinonapeptides related to syringomycins [3,4], syringotoxin [5,6] and syringostatins [7l, a group of antimicrobial and phytotoxic compounds produced by different isolates of P syrirzgae pv. syringae.…”

“…The preliminary results (details will be published elsewhere) of some biotests carried out with pseudomycin A, the major pseudomycin, in comparison with syringomycin E [3], a lipodepsinonapeptide extensively investigated for its biological activities [8], are included in this paper.…”

Syringopeptins, new phytotoxic lipodepsipeptides of Pseudomonas syringae pv. syringae

“…The 5 amino acid residues located between the N-terminal Ser and the C-terminal tripeptide, mostly of an uncommon structure, form the variable region of the peptide moiety. During our previous work on syringomycin [1,2] and syringotoxin [b] we had noticed that partially purified preparations of these toxins gave rise in HPLC (beside peaks due to the toxins themselves and to related compounds) to peaks due to more hydrophobic substances with a larger molecular size and a different amino acid composition. Our attention turned back to these substances when it was noticed that the phytotoxicity of the unfractionated mixture was only in part accounted for by their content of syringomycin or syringotoxin [8].…”

Mechanism of action of the phytotoxin syringomycin: a resistant mutant of Saccharomyces cerevisiae reveals an involvement of Ca2+ transport

“…Many strains of the bacterial pathogen Pseudomonas syringae pv. syringae produce this toxin which is a lipodepsipeptide with an Mr of 1224 (Segre et al, 1989). In addition to contributing io plant disease, syringomycin inhibits the growth of several fungi including the yeast Saccharomyces cerevisiae (Zhang & Takemoto, 1986.…”