Processing of proteins by the molecular chaperone Hsp104.

The molecular chaperone Hsp104 is an AAA+ ATPase (ATPase associated with a variety of cellular activities) from yeast that catalyzes protein disaggregation. Using mutagenesis, we impaired nucleotide binding or hydrolysis in the two nucleotide-binding domains (NBD) of Hsp104 and analyzed the consequences for chaperone function by monitoring ATP hydrolysis, polypeptide binding, polypeptide processing, and disaggregation. Our results reveal that ATP binding to NBD1 serves as a central regulatory switch for the chaperone; it triggers binding of polypeptides, and stimulates ATP hydrolysis in the C-terminal NBD2 by more than two orders of magnitude, implying that ATP hydrolysis in this domain is important for disaggregation.

The molecular chaperone Hsp104--a molecular machine for protein disaggregation.

At the Cold Spring Harbor Meeting on 'Molecular Chaperones and the Heat Shock Response' in May 1996, Susan Lindquist presented evidence that a chaperone of yeast termed Hsp104, which her group had been investigating for several years, is able to dissolve protein aggregates (Glover, J.R., Lindquist, S.

Substrate binding to the molecular chaperone Hsp104 and its regulation by nucleotides.

The Hsp104 protein from Saccharomyces cerevisiae is a member of the Hsp100/Clp family of molecular chaperones. It mediates the solubilization of aggregated proteins in an ATP-dependent process assisted by the Hsp70/40 system. Although the principal function of Hsp104 is well established, the mechanistic details of this catalyzed disaggregation are poorly understood.

Importance of low-oligomeric-weight species for prion propagation in the yeast prion system Sup35/Hsp104.

The [PSI+] determinant of Saccharomyces cerevisiae, consisting of the cytosolic translation termination factor Sup35, is a prion-type genetic element that induces an inheritable conformational change and converts the Sup35 protein into amyloid fibers. The molecular chaperone Hsp104 is required to maintain self-replication of [PSI+]. We observe in vitro that addition of catalytic amounts of Hsp104 to the prion-determining region of the NM domain of Sup35, Sup355-26, results in the dissociation of oligomeric Sup35 into monomeric species.

Dialyzer-augmented whole blood and plasma exchange for patients with hepatic or hepatorenal failure.

We have utilized new methods of dialyzer-augmented whole blood and plasma exchange tranfusion in the treatment of hepatic coma. The method employs the new fast flow Buselmeier shunt so that the exchange can be done from a peripheral radial artery shunt site rather than a shunt site in a more major vessel, such as the brachial artery. The method employs in-line dialysis of citrated (CPD) blood or plasma to normalize pH, electrolytes, and blood sugar while infusion heparinization decreases heparin requirements.