Native-like structure of a protein-folding intermediate bound to the chaperonin GroEL

Academic Article

Abstract

  • The chaperonin GroEL binds normative proteins in its central channel through hydrophobic interactions and initiates productive folding in this space underneath bound co-chaperone, GroES, in the presence of ATP. The questions of where along the folding pathway a protein is recognized by GroEL, and how much structure is present in a bound substrate have remained subjects of discussion, with some experiments suggesting that bound forms are fully unfolded and others suggesting that bound species are partially structured. Here we have studied a substrate protein, human dihydrofolate reductase (DHFR), observing in stopped-flow fluorescence experiments that it can rapidly bind to GroEL at various stages of folding. We have also analyzed the structure of the GroEL-bound protein using hydro-gen-deuterium exchange and NMR spectroscopy. The pattern and magnitude of amide proton protection indicate that the central parallel β-sheet found in native DHFR is present in a moderately stable state in GroEL-bound DHFR. Considering that the β- strands are derived from distant parts of the primary structure, this suggests that a native-like global topology is also present. We conclude that significant native-like structure is present in protein-folding intermediates bound to GroEL.
  • Digital Object Identifier (doi)

    Author List

  • Goldberg MS; Zhang J; Sondek S; Matthews CR; Fox RO; Horwich AL
  • Start Page

  • 1080
  • End Page

  • 1085
  • Volume

  • 94
  • Issue

  • 4