These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Domain-specific chaperone-induced expansion is required for beta-actin folding: a comparison of beta-actin conformations upon interactions with GroEL and tail-less complex polypeptide 1 ring complex (TRiC).
    Author: Villebeck L, Moparthi SB, Lindgren M, Hammarström P, Jonsson BH.
    Journal: Biochemistry; 2007 Nov 06; 46(44):12639-47. PubMed ID: 17939680.
    Abstract:
    Actin, an abundant cytosolic protein in eukaryotic cells, is dependent on the interaction with the chaperonin tail-less complex polypeptide 1 ring complex (TRiC) to fold to the native state. The prokaryotic chaperonin GroEL also binds non-native beta-actin, but is unable to guide beta-actin toward the native state. In this study we identify conformational rearrangements in beta-actin, by observing similarities and differences in the action of the two chaperonins. A cooperative collapse of beta-actin from the denatured state to an aggregation-prone intermediate is observed, and insoluble aggregates are formed in the absence of chaperonin. In the presence of GroEL, however, >90% of the aggregation-prone actin intermediate is kept in solution, which shows that the binding of non-native actin to GroEL is effective. The action of GroEL on bound flourescein-labeled beta-actin was characterized, and the structural rearrangement was compared to the case of the beta-actin-TRiC complex, employing the homo fluorescence resonance energy transfer methodology previously used [Villebeck, L., Persson, M., Luan, S.-L., Hammarström, P., Lindgren, M., and Jonsson, B.-H. (2007) Biochemistry 46 (17), 5083-93]. The results suggest that the actin structure is rearranged by a "binding-induced expansion" mechanism in both TRiC and GroEL, but that binding to TRiC, in addition, causes a large and specific separation of two subdomains in the beta-actin molecule, leading to a distinct expansion of its ATP-binding cleft. Moreover, the binding of ATP and GroES has less effect on the GroEL-bound beta-actin molecule than the ATP binding to TRiC, where it leads to a major compaction of the beta-actin molecule. It can be concluded that the specific and directed rearrangement of the beta-actin structure, seen in the natural beta-actin-TRiC system, is vital for guiding beta-actin to the native state.
    [Abstract] [Full Text] [Related] [New Search]