phomopsin has been researched along with ansamitocins* in 2 studies
2 other study(ies) available for phomopsin and ansamitocins
| Article | Year |
|---|---|
Binding selectivity of rhizoxin, phomopsin A, vinblastine, and ansamitocin P-3 to fungal tubulins: differential interactions of these antimitotic agents with brain and fungal tubulins.
The binding of four potent antimitotic agents, rhizoxin (RZX), phomopsin A (PMS-A), ansamitocin P-3 (ASMP-3), and vinblastine (VLB), to tubulins from RZX-sensitive and -resistant strains of Aspergillus nidulans, Schizosaccharomyces pombe, and Saccharomyces cerevisiae was investigated. Mycelial extracts to which RZX could bind contained beta-tubulin with Asn as the 100th amino acid residue (Asn-100) in all cases, and those without affinity for RZX contained beta-tubulins with either Ile-100 or Val-100. Though PMS-A shares the same binding site as RZX and ASMP-3 on porcine brain tubulin (Asn-100), only ASMP-3 bound Asn-100 fungal tubulins in a competitive manner with respect to RZX. PMS-A and VLB, which strongly bind to porcine brain tubulin, did not bind to any of the fungal mycelial extracts examined. The results indicate differential interactions of these antimitotic agents with brain and fungal tubulins. Topics: Animals; Antineoplastic Agents; Aspergillus nidulans; Binding Sites; Binding, Competitive; Brain; Brain Chemistry; Fungi; Lactones; Macrolides; Maytansine; Mycotoxins; Saccharomyces cerevisiae; Schizosaccharomyces; Swine; Tubulin; Vinblastine | 1992 |
Interaction of phomopsin A with porcine brain tubulin. Inhibition of tubulin polymerization and binding at a rhizoxin binding site.
Phomopsin A is an antimitotic cyclic peptide containing a 13-member ring including an ether linkage. It was isolated from the fungus Phomopsis leptostromiformis as the causal agent of lupinosis. Phomopsin A strongly inhibited microtubule assembly (IC50: 2.4 microM). Our study using radiolabeled phomopsin A, prepared biosynthetically by feeding L-[U-14C]isoleucine to the culture of P. leptostromiformis, indicated that at least two binding sites of phomopsin A exist on tubulin on the basis of a Scatchard analysis; i.e. the dissociation constants of a high affinity site (Kd1) and a low affinity site (Kd2) at 37 degrees were determined to be 1 x 10(-8) and 3 x 10(-7) M, respectively. Phomopsin A inhibited the binding of radiolabeled rhizoxin to tubulin with an inhibition constant (Ki) of 0.8 x 10(-8) M. This showed that the high affinity site of phomopsin A is identical to the rhizoxin binding site. The binding of the radiolabeled phomopsin A was also inhibited by rhizoxin and ansamitocin P-3, with an inhibition constant of 10(-7) M, and to a lesser extent by vinblastine. Phomopsin A had no inhibitory effect on colchicine binding to tubulin. Topics: Animals; Binding Sites; Binding, Competitive; Brain; Colchicine; Kinetics; Lactones; Macrolides; Maytansine; Microtubule Proteins; Mycotoxins; Polymers; Protein Conformation; Structure-Activity Relationship; Swine; Tubulin; Tubulin Modulators; Vinblastine | 1992 |