Atomic models by cryo-EM and site-directed spin labeling: application to the N-terminal region of Hsp16.5.
Structure
; 13(8): 1165-71, 2005 Aug.
Article
em En
| MEDLINE
| ID: mdl-16084388
ABSTRACT
We report an approach for determining the structure of macromolecular assemblies by the combined application of cryo-electron microscopy (cryo-EM) and site-directed spin labeling electron paramagnetic resonance spectroscopy (EPR). This approach is illustrated for Hsp16.5, a small heat shock protein that prevents the aggregation of nonnative proteins. The structure of Hsp16.5 has been previously studied by both cryo-EM and X-ray crystallography. The crystal structure revealed a roughly spherical protein shell with dodecameric symmetry; however, residues 1-32 were found to be disordered. The cryo-EM reconstruction at 13 A resolution appeared similar to the crystal structure but with additional internal density corresponding to the N-terminal regions of the 24 subunits. In this study, a systematic application of site-directed spin labeling and EPR spectroscopy was carried out. By combining the EPR constraints from spin label accessibilities and proximities with the cryo-EM density, we obtained an atomic model for a portion of the Hsp16.5 N-terminal region in the context of the oligomeric complex.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas Arqueais
/
Proteínas de Choque Térmico
/
Modelos Químicos
Idioma:
En
Revista:
Structure
Assunto da revista:
BIOLOGIA MOLECULAR
/
BIOQUIMICA
/
BIOTECNOLOGIA
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
Estados Unidos