English   español  
Por favor, use este identificador para citar o enlazar a este item: http://hdl.handle.net/10261/111016
COMPARTIR / IMPACTO:
Estadísticas
logo share SHARE logo core CORE   Add this article to your Mendeley library MendeleyBASE

Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL
Exportar a otros formatos:
Título

A Novel Two-domain Architecture Within the Amino Acid Kinase Enzyme Family Revealed by the Crystal Structure of Escherichia coli Glutamate 5-kinase

AutorMarco-Marín, Clara ; Gil-Ortiz, Fernando ; Pérez-Arellano, Isabel ; Cervera, Javier; Fita, Ignacio ; Rubio, Vicente
Palabras claveΔ1-pyrroline 5-carboxylate synthetase
PUA domain
ornithine synthesis
proline synthesis
amino acid kinase family
Fecha de publicación13-abr-2007
EditorAcademic Press
CitaciónJournal of Molecular Biology 367(5): 1431-1446 (2007)
ResumenGlutamate 5-kinase (G5K) makes the highly unstable product glutamyl 5-phosphate (G5P) in the initial, controlling step of proline/ornithine synthesis, being feedback-inhibited by proline or ornithine, and causing, when defective, clinical hyperammonaemia. We determined two crystal structures of G5K from Escherichia coli, at 2.9 Å and 2.5 Å resolution, complexed with glutamate and sulphate, or with G5P, sulphate and the proline analogue 5-oxoproline. E. coli G5K presents a novel tetrameric (dimer of dimers) architecture. Each subunit contains a 257 residue AAK domain, typical of acylphosphate-forming enzymes, with characteristic α3β8α4 sandwich topology. This domain is responsible for catalysis and proline inhibition, and has a crater on the β sheet C-edge that hosts the active centre and bound 5-oxoproline. Each subunit contains a 93 residue C-terminal PUA domain, typical of RNA-modifying enzymes, which presents the characteristic β5β4 sandwich fold and three α helices. The AAK and PUA domains of one subunit associate non-canonically in the dimer with the same domains of the other subunit, leaving a negatively charged hole between them that hosts two Mg ions in one crystal, in line with the G5K requirement for free Mg. The tetramer, formed by two dimers interacting exclusively through their AAK domains, is flat and elongated, and has in each face, pericentrically, two exposed active centres in alternate subunits. This would permit the close apposition of two active centres of bacterial glutamate-5-phosphate reductase (the next enzyme in the proline/ornithine-synthesising route), supporting the postulated channelling of G5P. The structures clarify substrate binding and catalysis, justify the high glutamate specificity, explain the effects of known point mutations, and support the binding of proline near glutamate. Proline binding may trigger the movement of a loop that encircles glutamate, and which participates in a hydrogen bond network connecting active centres, which is possibly involved in the cooperativity for glutamate. © 2007 Elsevier Ltd. All rights reserved.
Versión del editorhttp://dx.doi.org/10.1016/j.jmb.2007.01.073
URIhttp://hdl.handle.net/10261/111016
DOI10.1016/j.jmb.2007.01.073
Identificadoresdoi: 10.1016/j.jmb.2007.01.073
issn: 0022-2836
Aparece en las colecciones: (IBMB) Artículos
(IBV) Artículos
Ficheros en este ítem:
Fichero Descripción Tamaño Formato  
G5K_JMB2007.pdf1,8 MBAdobe PDFVista previa
Visualizar/Abrir
Mostrar el registro completo
 

Artículos relacionados:


NOTA: Los ítems de Digital.CSIC están protegidos por copyright, con todos los derechos reservados, a menos que se indique lo contrario.