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Titolo:
TRANSITION-STATE STRUCTURE FOR THE ADP-RIBOSYLATION OF RECOMBINANT G(I-ALPHA-1) SUBUNITS BY PERTUSSIS TOXIN
Autore:
SCHEURING J; BERTI PJ; SCHRAMM VL;
Indirizzi:
YESHIVA UNIV ALBERT EINSTEIN COLL MED,DEPT BIOCHEM,1300 MORRIS PK AVEBRONX NY 10461 YESHIVA UNIV ALBERT EINSTEIN COLL MED,DEPT BIOCHEM BRONX NY 10461
Titolo Testata:
Biochemistry
fascicolo: 9, volume: 37, anno: 1998,
pagine: 2748 - 2758
SICI:
0006-2960(1998)37:9<2748:TSFTAO>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
ISLET-ACTIVATING PROTEIN; NUCLEOPHILIC-SUBSTITUTION REACTIONS; GTP-BINDING PROTEINS; NUCLEOSIDE HYDROLASE; NAD-GLYCOHYDROLASE; ADENYLATE-CYCLASE; CARBOXYL TERMINUS; CRYSTAL-STRUCTURE; AMP NUCLEOSIDASE; ALPHA-SUBUNITS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
57
Recensione:
Indirizzi per estratti:
Citazione:
J. Scheuring et al., "TRANSITION-STATE STRUCTURE FOR THE ADP-RIBOSYLATION OF RECOMBINANT G(I-ALPHA-1) SUBUNITS BY PERTUSSIS TOXIN", Biochemistry, 37(9), 1998, pp. 2748-2758

Abstract

Pertussis toxin ADP-ribosylates a specific Cys side chain in the alpha-subunit of several G-proteins. Recombinant G(i alpha 1)-subunits were rapidly ADP-ribosylated in the absence of beta gamma-subunits, with a K-m of 800 mu M and a k(cat) of 40 min(-1). Addition of beta gamma-subunits decreases K-m to 0.3 mu M with little change of k(cat). Kinetic isotope effects established the transition-state structure for ADP-ribosylation of G(i alpha 1) subunits. The transition state is dissociative, with a 2.1 Angstrom bond to the nicotinamide leaving group and abond of 2.5 Angstrom to the sulfur nucleophile. The nucleophilic participation of G(i alpha 1) at the transition state is greater than thatfor water in the hydrolysis of NAD(+) by pertussis toxin. Crystal structures for G(i alpha 1) show the Cys nucleophile in a disordered segment or inaccessible for attack on NAD(+). Therefore, transition-state formation requires an altered G(i alpha 1) conformation to expose and ionize Cys. The transition state has been docked into the crystal structure of pertussis toxin in a geometry required for transition state formation.

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Documento generato il 18/09/20 alle ore 10:47:35