Biochemical properties of the proteasome from <i>Thermoplasma acidophilum</i>

Dahlmann, Burkhardt; Kuehn, Lothar; Grziwa, Anja; Zwickl, Peter; Baumeister, Wolfgang

doi:10.1111/j.1432-1033.1992.tb17249.x

Cited by 76 publications

(65 citation statements)

References 56 publications

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“…The kinetic parameters that we measured in our proteasome preparations are significantly different from the ones reported by Dahlmann et al [6] even when we raised the temperature of the assay to 91°C as in the other study. The reasons for this discrepancy are unclear but we note that proteasomes purified by the method of Dahlmann et al also differ from the ones purified by our procedure in other important properties, such as their dissociation and reconstitution [22].…”

Section: Specific Activities Of Selected Mutantscontrasting

confidence: 53%

“…Fax: (49) (89) 857 82641. E-mail: seemueller@vms.biochem.mpg.de mum of the proteasome tends to be slightly basic, making it unlikely that the enzyme is an aspartic protease [6]. Similarly, no inhibition is observable by up to 10 mM EDTA, by other chelators, or by phosphoramidon, making it unlikely that the proteasome is a metal protease [6,7].…”

Section: Introductionmentioning

confidence: 99%

“…Based on earlier publications which had classified the Thermoplasma proteasome as chymotryptic [6] we screened mutant proteins for proteolytic activity using the chymotryptic substrate Suc-Leu-Leu-Val-Tyr-AMC. Crude cell extracts of untransformed E. co# BL21(DE3) served as a negative control.…”

Section: £ Seemiiller Et Al/febs Letters 359 (1995) 173 178 33 Scrmentioning

confidence: 99%

“…E-mail: seemueller@vms.biochem.mpg.de mum of the proteasome tends to be slightly basic, making it unlikely that the enzyme is an aspartic protease [6]. Similarly, no inhibition is observable by up to 10 mM EDTA, by other chelators, or by phosphoramidon, making it unlikely that the proteasome is a metal protease [6,7]. Inhibition experiments with various cysteine and serine protease inhibitors have yielded ambiguous results and have mostly been successful at high or very high inhibitor concentrations [5][6][7][8][9], generally inhibiting only one of the different hydrolytic activities and sometimes concurrently activating others [5].…”

Section: Introductionmentioning

confidence: 99%

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The proteasome from Thermoplasma acidophilum is neither a cysteine nor a serine protease

et al. 1995

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The 20 S proteasome, found in eukaryotes and in the archaebacterium Thermoplasma acldophilum, forms the proteolytic core of the 26 S proteasome which is the central protease of the non-lysosomal protein degradation pathway. Inhibitor studies have indicated that the 20 S proteasome may be an unusual type of cysteine or serine protease and a recent study of the Thermoplasma [3 subunit has indicated that it carries the proteolytic activity. We have attempted to obtain information on the nature of the active site by mutating the only cysteine, both histidines and two completely conserved aspartates in the archaebacterial complex as well as all serines of the/3 subunit, without decreasing the catalytic activity of the enzyme to any significant extent. Indeed, mutation of the conserved aspartate in the/3 subunit increased the activity of the proteasome threefold. We conclude that the proteasome is not a cysteine or serine protease.

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Section: Specific Activities Of Selected Mutantscontrasting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Section: £ Seemiiller Et Al/febs Letters 359 (1995) 173 178 33 Scrmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The proteasome from Thermoplasma acidophilum is neither a cysteine nor a serine protease

et al. 1995

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“…The extent of proteolytic degradation is comparable to the degradation of the oxidant-damaged proteins suggesting that ubiquitin induces similar unfolding. The extent of proteolytic cleavage points to a broad specifity of the Thermoplasma acidophilum proteasome which is classified as chymotryptic [23]. The preponderance of cleavage products with molecular weights in the range of 1 kDa may be taken as an indication for the existence of a molecular ruler in the proteasome.…”

Section: Degradation Of Proteins In the Presence Of Ubiquitinmentioning

confidence: 99%

Thermoplasma acidophilum proteasomes degrade partially unfolded and ubiquitin‐associated proteins

Wenzel

Baumeister

1993

FEBS Letters

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It is shown that proteasomes from the archaebacterium Thermoplasma acidophilum selectively degrade substrate proteins partially unfolded by phenylhydrazine-or hydrogen peroxide-treatment. Surprisingly, the pre-incubation of the substrate proteins with ubiquitin is also sufficient to render them susceptible to proteolytic degradation by proteasomes. We propose that, upon spontaneously associating with the substrate protein, ubiquitin exerts a chaotropic effect on it; this may involve the exposure of hydrophobic segments of the polypeptide chain which are recognized by the binding sites of the proteasome.

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Displacement of housekeeping proteasome subunits by MHC-encoded LMPs: a newly discovered mechanism for modulating the multicatalytic proteinase complex.

et al. 1994

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The degradation of cytoplasmic antigens to peptides presented by class I MHC molecules is thought to be mediated by the ubiquitin/proteasome pathway. Support for this view came from our observation that the subunit composition of proteasomes can be changed by interferon‐gamma (IFN‐gamma) treatment. Thereby two subunits, LMP2 and LMP7, which are encoded in the MHC class II region, are incorporated into the proteasomal complex, whereas other subunits disappear. In the experiments reported in this communication we studied the subunit changes occurring in cell lines where the expression of LMP2 or LMP7 can be regulated individually either by IFN‐gamma induction or by applying a new system to control the expression of transfected LMPs. In both situations LMP2 induction leads exclusively to the disappearance of housekeeping subunit 2, whereas LMP7 affects only subunit 10. Subunit 2 was found to be 76% homologous to LMP2. Since incorporation of LMP2 into the proteasomal complex prevents processing of the subunit 2 precursor, we conclude that LMP2 displaces subunit 2 during assembly. Subunit displacement is most likely a general mechanism to modulate the catalytic activity of the proteasomal complex without changing its structure. Furthermore, the controlled incorporation of transfected subunits into the complex offers a new approach to study proteasome function in vivo.

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Biochemical properties of the proteasome from Thermoplasma acidophilum

Cited by 76 publications

References 56 publications

The proteasome from Thermoplasma acidophilum is neither a cysteine nor a serine protease

The proteasome from Thermoplasma acidophilum is neither a cysteine nor a serine protease

Thermoplasma acidophilum proteasomes degrade partially unfolded and ubiquitin‐associated proteins

Displacement of housekeeping proteasome subunits by MHC-encoded LMPs: a newly discovered mechanism for modulating the multicatalytic proteinase complex.

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