Crystal structure of wild-type chaperonin GroEL.
The 2.9A resolution crystal structure of apo wild-type GroEL was determined for the first time and represents the reference structure, facilitating the study of structural and functional differences observed in GroEL variants. Until now the crystal structure of the mutant Arg13Gly, Ala126Val GroEL was used for this purpose. We show that, due to the mutations as well as to the presence of a crystallographic symmetry, the ring-ring interface was inaccurately described. Analysis of the present structure allowed the definition of structural elements at this interface, essential for understanding the inter-ring allosteric signal transmission. We also show unambiguously that there is no ATP-induced 102 degrees rotation of the apical domain helix I around its helical axis, as previously assumed in the crystal structure of the (GroEL-KMgATP)(14) complex, and analyze the apical domain movements. These results enabled us to compare our structure with other GroEL crystal structures already published, allowing us to suggest a new route through which the allosteric signal for negative cooperativity propagates within the molecule. The proposed mechanism, supported by known mutagenesis data, underlines the importance of the switching of salt bridges.
Bartolucci
Cecilia
C
Istituto di Cristallografia, CNR, P.O. Box 10, I-00016 Monterotondo Stazione Roma, Italy. cecilia.bartolucci@ic.cnr.it
Lamba
Doriano
D
Grazulis
Saulius
S
Manakova
Elena
E
Heumann
Hermann
H
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000494:Allosteric Regulation; D018834:Chaperonin 60 / Q000737:chemistry* / Q000235:genetics; D018833:Chaperonins / Q000737:chemistry* / Q000235:genetics; D018360:Crystallography, X-Ray; D029968:Escherichia coli Proteins; D008958:Models, Molecular; D015394:Molecular Structure; D020125:Mutation, Missense; D011487:Protein Conformation / Q000187:drug effects
D018834:Chaperonin 60; D029968:Escherichia coli Proteins; D000255:Adenosine Triphosphate; D018833:Chaperonins