HSP100/Clp proteins: a common mechanism explains diverse functions

Schirmer, Eric C.; Glover, John R.; Singer, Mike A.; Lindquist, Susan

doi:10.1016/s0968-0004(96)10038-4

Cited by 557 publications

(578 citation statements)

References 47 publications

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“…The MR is the area bounded by these regions (residue 401 to residue 548). Areas of greater conservation are denoted by a thicker line (Schirmer et al, 1996), and signature sequences of the NBDs are denoted: A and B, the Walker-type P-loop motifs; S1 and S2, the two sensor regions. Asterisks indicate the positions of the mutations in sequenced mutants, and the amino acid substitutions are specified on the left.…”

Section: Plasmidsmentioning

confidence: 99%

“…The importance of the MR in Hsp104p function was unexpected due to its extreme variability: it is the most diverse region among class 1 HSP100/Clp proteins, in both length and sequence (Gottesman et al, 1990;Schirmer et al, 1996). In fact, it has previously been termed, very naturally, the "spacer" region (Gottesman et al, 1990).…”

Section: Critical Role Of the Middle Regionmentioning

confidence: 99%

“…Unexpectedly, seven of the remaining 12 substitutions clustered in the highly variable MR. In fact, every mutant recovered in the screen for disruption of Hsp104p regulation had at least one MR mutation.Although the amino acid sequence of the MR is highly variable, one small segment of 11 residues (Figure 2) exhibits moderate conservation among those members of the HSP100 family that function in thermotolerance (including plant, bacterial, and fungal members; Gottesman et al, 1990;Schirmer et al, 1996). Five of the seven MR mutations recovered in our screen were located in this small conserved segment (Figures 1, open box under MR; and 2).…”

mentioning

confidence: 94%

“…This survival capacity is directly attributable to Hsp104p's ability to resolubilize protein aggregates and, together with Hsp70p and Hsp40p, return them to their folded and active states (Parsell et al, 1994;Glover and Lindquist, 1998;Goloubinoff et al, 1999). This is in contrast to other heat shock proteins, which generally act by preventing aggregate accumulation or by promoting the degradation of misfolded proteins (Schirmer et al, 1996;Zolkiewski, 1999). During times of severe stress, the rate of protein aggregation exceeds the capacity of other heat shock proteins to prevent aggregate accumulation, and Hsp104p becomes critical to survival.…”

Section: Introductionmentioning

confidence: 99%

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Dominant Gain-of-Function Mutations in Hsp104p Reveal Crucial Roles for the Middle Region

Schirmer

Homann

Kowal

et al. 2004

MBoC

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Heat-shock protein 104 (Hsp104p) is a protein-remodeling factor that promotes survival after extreme stress by disassembling aggregated proteins and can either promote or prevent the propagation of prions (protein-based genetic elements). Hsp104p can be greatly overexpressed without slowing growth, suggesting tight control of its powerful protein-remodeling activities. We isolated point mutations in Hsp104p that interfere with this control and block cell growth. Each mutant contained alterations in the middle region (MR). Each of the three MR point mutations analyzed in detail had distinct phenotypes. In combination with nucleotide binding site mutations, Hsp104p T499I altered bud morphology and caused septin mislocalization, colocalizing with the misplaced septins. Point mutations in the septin Cdc12p suppressed this phenotype, suggesting that it is due to direct Hsp104p-septin interactions. Hsp104p A503V did not perturb morphology but stopped cell growth. Remarkably, when expressed transiently, the mutant protein promoted survival after extreme stress as effectively as did wild-type Hsp104p. Hsp104p A509D had no deleterious effects on growth or morphology but had a greatly reduced ability to promote thermotolerance. That mutations in an 11-amino acid stretch of the MR have such profound and diverse effects suggests the MR plays a central role in regulating Hsp104p function. INTRODUCTIONThe AAA ϩ proteins are ATPases associated with various cellular activities. They are important proteins with a great diversity of functions, including protein folding, membrane trafficking, organelle biogenesis, proteolysis, intracellular motility, and DNA replication (Neuwald et al., 1999;Vale, 2000;Ogura and Wilkinson, 2001). Little is known about how most AAA ϩ proteins recognize substrates and use ATP binding and hydrolysis to remodel them. The intrinsic complexity and multiplicity of conformational states of the AAA ϩ proteins make them difficult to study. The Clp/ HSP100 proteins are members of the AAA ϩ superfamily and have been the subject of intense biochemical analysis in vitro and genetic analysis in vivo (Wickner et al., 1999;Glover and Tkach, 2001). The functional unit of the yeast HSP100 heatshock protein 104 (Hsp104p) is composed of six monomers, each with two ATP binding sites (nucleotide binding domains one and two; NBD1 and NBD2) flanked by aminoterminal, middle, and carboxy-terminal regions (Figure 1).Hsp104p has remarkable functions, one of which is to allow survival after extreme stress. For example, yeast cells expressing Hsp104p are 1000 times more viable after exposure to temperatures Ն50°C or to an ethanol concentration of 20% than cells carrying deletions of HSP104 (Sanchez and Lindquist, 1990;Sanchez et al., 1992). This survival capacity is directly attributable to Hsp104p's ability to resolubilize protein aggregates and, together with Hsp70p and Hsp40p, return them to their folded and active states (Parsell et al., 1994;Glover and Lindquist, 1998;Goloubinoff et al., 1999). This is in contrast to other...

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Section: Plasmidsmentioning

confidence: 99%

Section: Critical Role Of the Middle Regionmentioning

confidence: 99%

mentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

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Dominant Gain-of-Function Mutations in Hsp104p Reveal Crucial Roles for the Middle Region

Schirmer

Homann

Kowal

et al. 2004

MBoC

Self Cite

108

111

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“…It consists of a ''hemi-20S particle'' composed only of ␤ subunits complexed, not with a CAD protein, but with a Clp-like protein (Rohrwild et al 1996). Clp proteins constitute a eubacterial proteolytic system with structural and functional similarities to eukaryotic CAD protein-containing proteasomes (Squires and Squires 1992;Schirmer et al 1996).…”

Section: The Proteasomal Regulatory Proteinsmentioning

confidence: 99%

The Evolution of the Conserved ATPase Domain (CAD): Reconstructing the History of an Ancient Protein Module

Swaffield

Purugganan

1997

J Mol Evol

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Abstract. The AAA proteins (ATPases Associated with a variety of cellular Activities) are found in eubacterial, archaebacterial, and eukaryotic species and participate in a large number of cellular processes, including protein degradation, vesicle fusion, cell cycle control, and cellular secretory processes. The AAA proteins are characterized by the presence of a 230 to 250-amino acid ATPase domain referred to as the Conserved ATPase Domain or CAD. Phylogenetic analysis of 133 CAD sequences from 38 species reveal that AAA CADs are organized into discrete groups that are related not only in structure but in cellular function. Evolutionary analyses also indicate that the CAD was present in the last common ancestor of eubacteria, archaebacteria, and eukaryotes. The eubacterial CADs are found in metalloproteases, while CAD-containing proteins in the archaebacterial and eukaryotic lineages appear to have diversified by a series of gene duplication events that lead to the establishment of different functional AAA proteins, including proteasomal regulatory, NSF/Sec, and Pas proteins. The phylogeny of the CADs provides the basis for establishing the patterns of evolutionary change that characterize the AAA proteins.

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