PDBsum entry 1la1

Chaperone

PDB id: 1la1

Contents

Protein chain

192 a.a. *

Waters ×274

* Residue conservation analysis

References listed in PDB file

Key reference

• Title: Structural plasticity and noncovalent substrate binding in the groel apical domain. A study using electrospay ionization mass spectrometry and fluorescence binding studies.
• Authors: A.E.Ashcroft, A.Brinker, J.E.Coyle, F.Weber, M.Kaiser, L.Moroder, M.R.Parsons, J.Jager, U.F.Hartl, M.Hayer-Hartl, S.E.Radford.
• Ref.: J Biol Chem, 2002, 277, 33115-33126. [DOI no: 10.1074/jbc.M203398200]
• PubMed id: 12065585

Abstract

Advances in understanding how GroEL binds to non-native proteins are reported. Conformational flexibility in the GroEL apical domain, which could account for the variety of substrates that GroEL binds, is illustrated by comparison of several independent crystallographic structures of apical domain constructs that show conformational plasticity in helices H and I. Additionally, ESI-MS indicates that apical domain constructs have co-populated conformations at neutral pH. To assess the ability of different apical domain conformers to bind co-chaperone and substrate, model peptides corresponding to the mobile loop of GroES and to helix D from rhodanese were studied. Analysis of apical domain-peptide complexes by ESI-MS indicates that only the folded or partially folded apical domain conformations form complexes that survive gas phase conditions. Fluorescence binding studies show that the apical domain can fully bind both peptides independently. No competition for binding was observed, suggesting the peptides have distinct apical domain-binding sites. Blocking the GroES-apical domain-binding site in GroEL rendered the chaperonin inactive in binding GroES and in assisting the folding of denatured rhodanese, but still capable of binding non-native proteins, supporting the conclusion that GroES and substrate proteins have, at least partially, distinct binding sites even in the intact GroEL tetradecamer.

Figure 1.
Fig. 1. Apical domain constructs of GroEL. A, GroEL apical domain constructs indicating the amino acid residues included and modifications made in the proteins expressed for these studies. B, ribbon diagram showing a comparison of the overall structures of five independent GroEL apical domains: C-His ApEL (determined here) ( purple), N-His ApEL (22) (red), ApEL-(191-336)·peptide complex (19) (yellow), intact WT GroEL (9) (blue), and a GroEL·ADP complex (45) (green). The diagram shows the conformational flexibility in the region around helices H and I. C, r.m.s. deviation plot showing the differences in C- positions between C-His ApEL and N-His ApEL (22) (unbroken line), and C-His ApEL and an ApEL-(191-336)·peptide complex (19) (dotted line).

The above figure is reprinted by permission from the ASBMB: J Biol Chem (2002, 277, 33115-33126) copyright 2002.