Neil A. Ranson

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The chaperonin GroEL drives its protein-folding cycle by cooperatively binding ATP to one of its two rings, priming that ring to become folding-active upon GroES binding, while simultaneously discharging the previous folding chamber from the opposite ring. The GroEL-ATP structure, determined by cryo-EM and atomic structure fitting, shows that the(More)
The outer membrane protein PulD (secretin) of Klebsiella oxytoca is required for transport of pullulanase across this membrane. We have purified a multimeric PulD complex from an Escherichia coli strain expressing all the proteins involved in pullulanase secretion. The outer membrane-anchored lipoprotein PulS was found to copurify with PulD. The molar ratio(More)
Protein folding mediated by the molecular chaperone GroEL occurs by its binding to non-native polypeptide substrates and is driven by ATP hydrolysis. Both of these processes are influenced by the reversible association of the co-protein, GroES (refs 2-4). GroEL and other chaperonin 60 molecules are large, cylindrical oligomers consisting of two stacked(More)
Single-stranded RNA (ssRNA) viruses, which include major human pathogens, package their genomes as they assemble their capsids. We show here that the organization of the viral genomes within the capsids provides intriguing insights into the highly cooperative nature of the assembly process. A recent cryo-electron microscopy structure of bacteriophage MS2,(More)
The double-ring chaperonin GroEL and its lid-like cochaperonin GroES form asymmetric complexes that, in the ATP-bound state, mediate productive folding in a hydrophilic, GroES-encapsulated chamber, the so-called cis cavity. Upon ATP hydrolysis within the cis ring, the asymmetric complex becomes able to accept non-native polypeptides and ATP in the open,(More)
The binding of nucleotides and chaperonin-10 (cpn10) to the Escherichia coli chaperonin-60 (cpn60) and their effect upon the molecular symmetry has been examined both kinetically and at equilibrium. ATP binds tightly and is hydrolysed on only one heptameric ring of the cpn60 tetradecamer at a time, thus inducing asymmetry in the cpn60 oligomer even in the(More)
Chaperonins use energy derived from ATP hydrolysis to enhance the efficiency of protein folding by a mechanism which remains a matter of debate. Here, we show that the kinetics of spontaneous and assisted folding of mitochondrial malate dehydrogenase are quantitatively described by a simple physical model. The protein folds from non-native chains by the(More)
Transmission electron microscopy (EM) is a versatile technique that can be used to image biological specimens ranging from intact eukaryotic cells to individual proteins >150kDa. There are several strategies for preparing samples for imaging by EM, including negative staining and cryogenic freezing. In the last few years, cryo-EM has undergone a 'resolution(More)
Mitochondrial malate dehydrogenase (mMDH) folds more rapidly in the presence of GroEL, GroES and ATP than it does unassisted. The increase in folding rate as a function of the concentration of GroEL-ES reaches a maximum at a stoichiometry which is approximately equimolar (mMDH subunits:GroEL oligomer) and with an apparent dissociation constant K' for the(More)