TY - JOUR
T1 - Differential effects of active isomers, segments, and analogs of dolastatin 10 on ligand interactions with tubulin. Correlation with cytotoxicity
AU - Bai, Ruoli
AU - Roach, Mary Carmen
AU - Jayaram, Srirangam K.
AU - Barkoczy, Jozef
AU - Pettit, George
AU - Luduena, Richard F.
AU - Hamel, Ernest
N1 - Funding Information:
HealthS cienceC enterw ass upportedb y Grants CA26376 from the NationalI nstituteso f Health and AQ-0726f rom the Welch Foundation.W ork performeda t the Arizona StateU niversityC ancerR esearchI nstitutew as supported by the Arizona DiseaseC ontrol ResearchC ommission, Outstanding Investigator Grant CA-443440-lA1-02 awarded by the Division of Cancer Treatment of the NationalCancerInstituteth, eFannieE.RippelFoundation, the Robert B. Dalton Endowment Fund, Eleanor W. Libbey, and the Donald Ware Waddell Foundation.
PY - 1993/4/6
Y1 - 1993/4/6
N2 - Dolastatin 10 is a potent antimitotic peptide isolated from the marine mollusk Dolabella auricularia. Four of its five residues are modified amino acids (in sequence, dolavaline, valine, dolaisoleuine, dolaproine, dolaphenine). Besides inhibiting tubulin polymerization, dolastatin 10 noncompetitively inhibits vinca alkaloid binding to tubulin, inhibits nucleotide exchange and formation of the βs cross-link, and stabilizes the colchicine binding activity of tubulin. To examine the mechanism of action of dolastatin 10 we prepared six chiral isomers, one tri- and one tetrapeptide segment, and one pentapeptide analog of dolastatin 10, all of which differ little from dolastatin 10 as inhibitors of tubulin polymerization. However, only two of the chiral isomers were similar to dolastatin 10 in their cytotoxicity for L1210 murine leukemia cells and in their effects on vinblastine binding, nucleotide exchange, βs cross-link formation, and colchicine binding. These were isomer 2, with reversal of configuration at position C(19a) in the dolaisoleuine moiety, and isomer 19, with reversal of configuration at position C(6) in the dolaphenine moiety. The pentapeptides with reduced cytotoxicity and reduced effects on tubulin interactions with other ligands were all modified in the dolaproine moiety at positions C(9) and/ or C(10). The tripeptide and tetrapeptide segments which inhibited polymerization but not ligand interactions were the amino terminal tripeptide (lacking dolaproine and dolaphenine) and the carboxyl terminal tetrapeptide (lacking dolavaline). We speculate that strong inhibition of other ligand interactions with tubulin requires stable peptide binding to tubulin (i.e. slow dissociation), but that inhibition of polymerization requires only rapid binding to tubulin.
AB - Dolastatin 10 is a potent antimitotic peptide isolated from the marine mollusk Dolabella auricularia. Four of its five residues are modified amino acids (in sequence, dolavaline, valine, dolaisoleuine, dolaproine, dolaphenine). Besides inhibiting tubulin polymerization, dolastatin 10 noncompetitively inhibits vinca alkaloid binding to tubulin, inhibits nucleotide exchange and formation of the βs cross-link, and stabilizes the colchicine binding activity of tubulin. To examine the mechanism of action of dolastatin 10 we prepared six chiral isomers, one tri- and one tetrapeptide segment, and one pentapeptide analog of dolastatin 10, all of which differ little from dolastatin 10 as inhibitors of tubulin polymerization. However, only two of the chiral isomers were similar to dolastatin 10 in their cytotoxicity for L1210 murine leukemia cells and in their effects on vinblastine binding, nucleotide exchange, βs cross-link formation, and colchicine binding. These were isomer 2, with reversal of configuration at position C(19a) in the dolaisoleuine moiety, and isomer 19, with reversal of configuration at position C(6) in the dolaphenine moiety. The pentapeptides with reduced cytotoxicity and reduced effects on tubulin interactions with other ligands were all modified in the dolaproine moiety at positions C(9) and/ or C(10). The tripeptide and tetrapeptide segments which inhibited polymerization but not ligand interactions were the amino terminal tripeptide (lacking dolaproine and dolaphenine) and the carboxyl terminal tetrapeptide (lacking dolavaline). We speculate that strong inhibition of other ligand interactions with tubulin requires stable peptide binding to tubulin (i.e. slow dissociation), but that inhibition of polymerization requires only rapid binding to tubulin.
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U2 - 10.1016/0006-2952(93)90051-W
DO - 10.1016/0006-2952(93)90051-W
M3 - Article
C2 - 8471072
AN - SCOPUS:0027537616
SN - 0006-2952
VL - 45
SP - 1503
EP - 1515
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
IS - 7
ER -