Portal de Periódicos da CAPES

Ustiloxins, new antimitotic cyclic peptides: Interaction with porcine brain tubulin

1995; Elsevier BV; Volume: 49; Issue: 10 Linguagem: Inglês

10.1016/0006-2952(95)00072-8

1873-2968

Yin Li, Yukiko Koiso, Hisayoshi Kobayashi, Yuichi Hashimoto, Shigeo Iwasaki,

Seaweed-derived Bioactive Compounds

Biochemical and electron microscopic studies demonstrated that ustiloxins A-D, which are antimitotic 13-membered cyclic peptides produced by the rice plant pathogen Ustilaginoidea virens, strongly inhibited the polymerization of porcine brain tubulin in vitro and depolymerized pre-formed microtubules The IC50 values of polymerization inhibited by ustiloxins A-D were determined to be 0.7, 2.8, 4.4 and 6.6 μM, respectively, under the experimental conditions used, indicating that ustiloxin A is the most potent inhibitor of tubulin polymerization currently known. Ustiloxins A-C were found to inhibit the binding of radiolabelled rhizoxin to tubulin with inhibition constants (Ki) of 0.08, 0.13 and 0.23 μM, respectively, and also inhibited the binding of radiolabelled phomopsin A as strongly as rhizoxin. These results suggest that the binding site of ustiloxins is identical with that of rhizoxin.