Concanamycin a, the specific inhibitor of V-ATPases, binds to the V-o subunit c

Autor(en): Huss, M 
Ingenhorst, G
Konig, S
Gassel, M
Drose, S
Zeeck, A
Altendorf, K 
Wieczorek, H 
Stichwörter: BAFILOMYCIN; Biochemistry & Molecular Biology; CELLS; CONTAINS; H+-ATPASE; MIDGUT; P-TYPE; PLASMA-MEMBRANE; PROTEINS; PURIFICATION; TOBACCO HORNWORM
Erscheinungsdatum: 2002
Herausgeber: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Journal: JOURNAL OF BIOLOGICAL CHEMISTRY
Volumen: 277
Ausgabe: 43
Startseite: 40544
Seitenende: 40548
Zusammenfassung: 
Vacuolar-type ATPase (V-ATPase) purified from the midgut of the tobacco hornworm Manduca sexta is inhibited 50% by 10 nm of the plecomacrolide concanamycin A, the specific inhibitor of V-ATPases. To determine the binding site(s) of that antibiotic in the enzyme complex, labeling with the semisynthetic 9-O-[p-(trifluoroethyldiazirinyl)-benzoyl]-21,23-dideoxy-23-[I-125]i odo-concanolide A (J-concanolide A) was performed, which still inhibits the V-ATPase 50% at a concentration of 15-20 mum. Upon treatment with UV light, a highly reactive carbene is generated from this concanamycin derivative, resulting in the formation of a covalent bond to the enzyme. In addition, the radioactive tracer 1251 makes the detection of the labeled subunit(s) feasible. Treatment of the V-1/V-o holoenzyme, the V-o complex, and the V-ATPase containing goblet cell apical membranes with concanolide resulted in the labeling of only the proteolipid, subunit c, of the proton translocating V-o complex. Binding of J-concanolide A to subunit c was prevented in a concentration-dependent manner by concanamycin A, indicating that labeling was specific. Binding was also prevented by the plecomacrolides bafilomycin A(1) and B-1 respectively, but not by the benzolactone enamide salicylihalamide, a member of a novel class of V-ATPase inhibitors.
ISSN: 00219258
DOI: 10.1074/jbc.M207345200

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