title: Structure-activity relationship within a series of degradation products of tautomycin.
abstract: Tautomycin, a protein serine/threonine phosphatase inhibitor, was chemically degraded, and five derivatives were investigated for their biological activities. None of them exerted any inhibitory effects on the activity of protein phosphatase types 1 and 2A. However, one derivative, named TM2a, induced a significant morphological change (bleb-formation) of human myeloid leukemia K562 cells. TM2b, the trimethyl ester of TM2, did not induce bleb-formation. Thus, the maleic anhydride structure played an important role in the biological activity. The biological properties of TM2a toward K562 cells resembled those of a phorbol ester, rather than of tautomycin. The phorbol ester-induced bleb formation was abrogated by a non-specific inhibitor of protein kinases, staurosporine, and by an inhibitor of protein kinase C (PKC), H-7, but TM2a-induced bleb formation was abrogated only by staurosporine. Enhanced phosphorylation of the two proteins was observed after their exposure to TM2a. This suggest that the effect was not due to any inhibition of protein phosphatase 1 or 2A, but rather to the activation of an unidentified kinase, possibly of the PKC family, or to inhibition of a protein phosphatase other than type 1 or 2A.
authors.affiliation: Department of Bioengineering, Tokyo Institute of Technology, Yokohama, Japan.
authors.forename: U
authors.initials: U
authors.lastname: Nishiyama
authors.forename: M
authors.initials: M
authors.lastname: Ubukata
authors.forename: J
authors.initials: J
authors.lastname: Magae
authors.forename: T
authors.initials: T
authors.lastname: Kataoka
authors.forename: F
authors.initials: F
authors.lastname: Erdödi
authors.forename: D J
authors.initials: DJ
authors.lastname: Hartshorne
authors.forename: K
authors.initials: K
authors.lastname: Isono
authors.forename: K
authors.initials: K
authors.lastname: Nagai
authors.forename: H
authors.initials: H
authors.lastname: Osada
mesh_terms: D000935:Antifungal Agents / Q000378:metabolism / Q000494:pharmacology; D001673:Biodegradation, Environmental; D006801:Humans; D007951:Leukemia, Myeloid / Q000473:pathology*; D010703:Phorbol Esters / Q000378:metabolism / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D010975:Platelet Aggregation Inhibitors / Q000378:metabolism*; D054645:Protein Phosphatase 1; D011714:Pyrans; D013141:Spiro Compounds; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured
chemical_list: D000935:Antifungal Agents; D010703:Phorbol Esters; D010975:Platelet Aggregation Inhibitors; D011714:Pyrans; D013141:Spiro Compounds; C053079:tautomycin; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1