Hsp104 is a molecular chaperone required for stress tolerance and for maintenance of [psi(+)] prions in the budding yeast Saccharomyces cerevisiae (1,2). HSP104 is a hexameric protein with two AAA ATPase domains (N- and SLCterminal nucleotide-binding domains NBD1 and NBD2, respectively) per monomer (3). NBD1 and NBD2 have very different catalytic properties, but each shows positive cooperativity in hydrolysis (3,4). Point mutations in either of the two nucleotide-binding domains (NBD) of Hsp104 (NBD1 and NBD2) eliminate its thermotolerance function in vivo (5). Hsp104 interacts with Hsp90 cochaperones in respiring yeast (1). The primary function of Hsp104 in prion propagation is to disassemble prion aggregates and generate the small prion seeds that initiate new rounds of prion propagation (possibly assisted by Hsp70-Ssa) (6).
Function:
Hsp104 is a molecular chaperone required for stress tolerance and for maintenance of [psi(+)] prions in the budding yeast Saccharomyces cerevisiae. Hsp104 is vital to protect yeast cells against high temperature and high concentration of ethanol. It is not required for normal growth.
Subunit:
Homohexamer, forming a ring with a central pore. The hexamer is stabilized by high protein concentrations and by ADP or ATP. Oligomerization influences ATP hydrolysis activity at NBD2. Interacts with YDJ1. Interacts (via SLCterminal DDLD tetrapeptide) with CNS1, CPR7 and STI1 (via TPR repeats); under respiratory growth conditions.
Subcellular Location:
Cytoplasmic and Nuclear
Similarity:
Belongs to the ClpA/ClpB family.
SWISS:
P31539
Gene ID:
850633
Database links:
Entrez Gene: 850633 Saccharomyces cerevisiae
SwissProt: P31539 Saccharomyces cerevisiae
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