Asymmetric interactions of ATP with the AAA+ ClpX6 unfoldase: allosteric control of a protein machine.
Cell
; 121(7): 1017-27, 2005 Jul 01.
Article
en En
| MEDLINE
| ID: mdl-15989952
ATP hydrolysis by AAA+ ClpX hexamers powers protein unfolding and translocation during ClpXP degradation. Although ClpX is a homohexamer, positive and negative allosteric interactions partition six potential nucleotide binding sites into three classes with asymmetric properties. Some sites release ATP rapidly, others release ATP slowly, and at least two sites remain nucleotide free. Recognition of the degradation tag of protein substrates requires ATP binding to one set of sites and ATP or ADP binding to a second set of sites, suggesting a mechanism that allows repeated unfolding attempts without substrate release over multiple ATPase cycles. Our results rule out concerted hydrolysis models involving ClpX(6)*ATP(6) or ClpX(6)*ADP(6) and highlight structures of hexameric AAA+ machines with three or four nucleotides as likely functional states. These studies further emphasize commonalities between distant AAA+ family members, including protein and DNA translocases, helicases, motor proteins, clamp loaders, and other ATP-dependent enzymes.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas Bacterianas
/
Adenosina Trifosfato
/
ATPasas de Translocación de Protón Bacterianas
/
Proteínas de Escherichia coli
/
Endopeptidasa Clp
Idioma:
En
Revista:
Cell
Año:
2005
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos