CONFORMATIONAL-CHANGES IN THE GROEL OLIGOMER DURING THE FUNCTIONAL CYCLE

Citation
O. Llorca et al., CONFORMATIONAL-CHANGES IN THE GROEL OLIGOMER DURING THE FUNCTIONAL CYCLE, Journal of structural biology, 118(1), 1997, pp. 31-42
Citations number
37
Categorie Soggetti
Cell Biology",Biology
ISSN journal
10478477
Volume
118
Issue
1
Year of publication
1997
Pages
31 - 42
Database
ISI
SICI code
1047-8477(1997)118:1<31:CITGOD>2.0.ZU;2-7
Abstract
The conformational changes that the GroEL oligomer undergoes upon nucl eotide and cochaperonin GroES binding have been studied using electron microscopy and image processing techniques. Average side views of the three allosteric states (TT, TR, and RR, which correspond to none, on e, or both of the two heptameric rings of the GroEL oligomer occupied by nucleotide, respectively) of GroEL and GroEL-GroES complexes for AD P, ATP, and two nonhydrolyzable analogs (AMP-PNP and ATP gamma S) have been obtained at 20-25 Angstrom resolution. Both AMP-PNP and ATP indu ce similar conformational shifts in the apical domains of GroEL, At th e TR state, only one of the GroEL rings shows an upward and outward mo vement of the apical domains (''open state''). At the RR state for AMP -PNP and ATP, both GroEL rings undergo conformational changes, albeit of different magnitude, giving rise to a structurally asymmetric parti cle (one ring in the ''open'' state, while the other is in an ''interm ediate'' state). These changes are also observed when GroEL is incubat ed with ADP and P-i, but not with ADP, which suggests that upon ATP bi nding, GroEL undergoes a conformational change that is partly maintain ed after ATP hydrolysis and as long as ADP and P-i are bound to the Gr oEL ring. The conformational changes undergone by GroEL are discussed within the framework of a proposed GroEL cycle mechanism. (C) 1997 Aca demic Press.