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. Moreover, we show that Hsp104 actively unfolds its polypeptide substrates during processing, demonstrating that AAA+ proteins involved in disaggregation share a common threading mechanism with AAA+ proteins mediating protein unfolding/degradation.
Schaupp
Andreas
A
Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany.
Marcinowski
Moritz
M
Grimminger
Valerie
V
Bösl
Benjamin
B
Walter
Stefan
S
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001665:Binding Sites; D002384:Catalysis; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D009154:Mutation / Q000235:genetics; D009711:Nucleotides / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D017510:Protein Folding; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012680:Sensitivity and Specificity; D013379:Substrate Specificity
D006360:Heat-Shock Proteins; D009711:Nucleotides; D010455:Peptides; D029701:Saccharomyces cerevisiae Proteins; C070972:HsP104 protein, S cerevisiae; D000255:Adenosine Triphosphate