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Hydrogen-deuterium exchange of 39 amide protons of Bacillus amyloliquefaciens ribonuclease (barnase) was analyzed by two-dimensional nuclear magnetic resonance in the presence of micromolar concentrations of the molecular chaperones GroEL and SecB. Both chaperones bound to native barnase under physiological conditions and catalyzed exchange of deeply buried(More)
Nanoparticles containing magnetic materials, such as magnetite (Fe3O4), are particularly useful for imaging and separation techniques. As these nanoparticles are generally considered to be biologically and chemically inert, they are typically coated with metal catalysts, antibodies or enzymes to increase their functionality as separation agents. Here, we(More)
BACKGROUND The microtubule associated protein tau is the principle component of neurofibrillar tangles, which are a characteristic marker in the pathology of Alzheimer's disease; similar lesions are also observed after chronic alcohol abuse. Formaldehyde is a common environmental contaminant and also a metabolite of methanol. Although many studies have been(More)
The large surface area and small size of nanoparticles provide properties and applications that are distinct from those of bulk materials. The ability of nanoparticles to influence protein folding and aggregation is interesting, not only because of the potential beneficial applications, but also the potential risks to human health and the environment. This(More)
Trigger factor (TF) is the first chaperone encountered by the nascent chain in bacteria and forms a stoichiometric complex with the ribosome. However, the functional significance of the high cytosolic concentration of uncomplexed TF, the majority of which is dimeric, is unknown. To gain insight into TF function, we investigated the TF concentration(More)
Within cells, proteins can co-assemble into functionally integrated and spatially restricted multicomponent complexes. Often, the affinities between individual proteins are relatively weak, and proteins within such clusters may interact only indirectly with many of their other protein neighbors. This makes proteomic characterization difficult using methods(More)
In budding yeast, the essential functions of Hsp70 chaperones Ssa1-4 are regulated through expression level, isoform specificity, and cochaperone activity. Suggesting a novel regulatory paradigm, we find that phosphorylation of Ssa1 T36 within a cyclin-dependent kinase (CDK) consensus site conserved among Hsp70 proteins alters cochaperone and client(More)
Peptides and proteins possess an inherent propensity to self-assemble into generic fibrillar nanostructures known as amyloid fibrils, some of which are involved in medical conditions such as Alzheimer disease. In certain cases, such structures can self-propagate in living systems as prions and transmit characteristic traits to the host organism. The(More)
Ure2p is the protein determinant of the Saccharomyces cerevisiae prion state [URE3]. Constitutive overexpression of the HSP70 family member SSA1 cures cells of [URE3]. Here, we show that Ssa1p increases the lag time of Ure2p fibril formation in vitro in the presence or absence of nucleotide. The presence of the HSP40 co-chaperone Ydj1p has an additive(More)
Previous results suggest that methylotrophic yeasts may contain factors that modulate prion stability. Alcohol oxidase (AOX), a key enzyme in methanol metabolism, is an abundant protein that is specific to methylotrophic yeasts. We examined the effect of Pichia pastoris AOX1 on prion phenotypes in Saccharomyces cerevisiae. The S. cerevisiae prion states(More)