FIG. 7.

Structures of syringomycin, syringostatin, syringotoxin, and pseudomycin. The four lipodepsinonapeptides differ in the amino acid sequence between positions 2 and 6. The 3-hydroxy fatty acyl group is a derivative of either decanoic acid (syringomycin), dodecanoic acid (syringomycin and syringostatin), tetradecanoic acid (all four lipodepsinonapeptides), or hexadecanoic acid (pseudomycin); some forms of pseudomycin are acylated by 3,4-dihydroxytetradecanoate or 3,4-dihydroxyhexadecanoate. Abbreviations of nonstandard amino acids: Asp(3-OH), 3-hydroxyaspartic acid; Dab, 2,4-diaminobutyric acid; Dhb, 2,3-dehydroaminobutyric acid; Hse, homoserine; Orn, ornithine; Thr(4-Chl), 4-chlorothreonine; aThr, allothreonine.