Effects of Catalytic Action and Ligand Binding on Conformational Ensembles of Adenylate Kinase.
Biochemistry
; 56(34): 4559-4567, 2017 08 29.
Article
em En
| MEDLINE
| ID: mdl-28767234
ABSTRACT
Crystal structures of adenylate kinase (AdK) from Escherichia coli capture two states an "open" conformation (apo) obtained in the absence of ligands and a "closed" conformation in which ligands are bound. Other AdK crystal structures suggest intermediate conformations that may lie on the transition pathway between these two states. To characterize the transition from open to closed states in solution, X-ray solution scattering data were collected from AdK in the apo form and with progressively increasing concentrations of five different ligands. Scattering data from apo AdK are consistent with scattering predicted from the crystal structure of AdK in the open conformation. In contrast, data from AdK samples saturated with Ap5A do not agree with that calculated from AdK in the closed conformation. Using cluster analysis of available structures, we selected representative structures in five conformational states open, partially open, intermediate, partially closed, and closed. We used these structures to estimate the relative abundances of these states for each experimental condition. X-ray solution scattering data obtained from AdK with AMP are dominated by scattering from AdK in the open conformation. For AdK in the presence of high concentrations of ATP and ADP, the conformational ensemble shifts to a mixture of partially open and closed states. Even when AdK is saturated with Ap5A, a significant proportion of AdK remains in a partially open conformation. These results are consistent with an induced-fit model in which the transition of AdK from an open state to a closed state is initiated by ATP binding.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Fosfatos de Dinucleosídeos
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Difosfato de Adenosina
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Trifosfato de Adenosina
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Adenilato Quinase
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Proteínas de Escherichia coli
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Escherichia coli
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Biochemistry
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
Estados Unidos