The refolding of the tetrameric enzyme tryptophanase was facilitated by the chaperonin GroE. Maximum refolding yield of tryptophanase molecules (about 80%) was attained in the presence of a 15-fold excess of GroE 21-mer over tryptophanase monomer. The GroEL subunit was required for this improvement in refolding yield, whereas the GroES subunit was not. Light scattering experiments of the refold...

Although chaperonin-assisted protein folding has been studied in vitro by a number of investigators, the feature(s) of the unfolded polypeptide that are recognized and bound by chaperonins is not known. We have addressed this question using the precursor of the small subunit of ribulose-1,5-bisphosphate carboxylase (pS) as a substrate for GroEL. The protein was expressed in Escherichia coli as ...

Although ribonucleases fold into correct tertiary conformation in vitro guided solely by information contained in the primary amino acid sequence (Sela, M., White, F. H., and Anfinsen, C. B. (1957) Science 124, 691-693), it is not clear whether folding of these proteins proceeds unassisted in a complex intracellular environment. We describe here the specific and high affinity binding of groEL, ...

0022-2836/$ see front matter q 2005 E Present address: S. Falke, Departm William Jewell College, 500 College 64068, USA. Abbreviations used: EM, electron single large monomer of glutamine normal mode flexible fitting. E-mail addresses of the correspon [email protected]; mfisher1@kumc The 13 Å resolution structures of GroEL bound to a single monomer of the protein substrate glutamine synthetase (G...

Phage P22 wild-type (WT) coat protein does not require GroEL/S to fold but temperature-sensitive-folding (tsf) coat proteins need the chaperone complex for correct folding. WT coat protein and all variants absolutely require P22 scaffolding protein, an assembly chaperone, to assemble into precursor structures termed procapsids. Previously, we showed that a global suppressor (su) substitution, T...

Human heat shock protein (hsp) 70 and bacterial protein groEL promote leakage of calcein from liposomes induced by human serum albumin signal peptide, by S. aureus alpha toxin or by diphtheria toxin. Hsp 70 and groEL, as well as two mycobacterial homologues hsp 71 and hsp 65, induce ion conducting pores across planar lipid bilayers at low or neutral pH. It is concluded that hsp induce pores in ...

Oligomeric, ring-shaped nano-machines that are fueled by ATP are ubiquitous in all three kingdoms of life and are involved in a wide range of processes that include, for example, protein folding, protein degradation, DNA and RNA remodeling, and protein insertion into membranes (for review, see ref. 1). These assemblies are true machines because they carry out work by undergoing movements that a...

The commonly accepted dogma of the bacterial GroE chaperonin system entails protein folding mediated by cycles of several ATP-dependent sequential steps where GroEL interacts with the folding client protein. In contrast, we herein report GroES-mediated dynamic remodeling (expansion and compression) of two different protein substrates during folding: the endogenous substrate MreB and carbonic an...

The double-ring chaperonin GroEL mediates protein folding in the central cavity of a ring bound by ATP and GroES, but it is unclear how GroEL cycles from one folding-active complex to the next. We observe that hydrolysis of ATP within the cis ring must occur before either nonnative polypeptide or GroES can bind to the trans ring, and this is associated with reorientation of the trans ring apica...

Clostridium difficile is a pathogen which is responsible for diarrhea and colitis, particularly after treatment with antibiotics. Clinical signs are mainly due to two toxins, TcdA and TcdB. However, the first step of pathogenesis is the colonization process. We evaluated C. difficile surface proteins as vaccine antigens in the hamster model to prevent intestinal colonization. This vaccination i...