F
IPR001353

Proteasome, subunit alpha/beta

InterPro entry
Short nameProteasome_sua/b
Overlapping
homologous
superfamilies
 
family relationships

Description

ATP-dependent protease complexes are present in all three kingdoms of life, where they rid the cell of misfolded or damaged proteins and control the level of certain regulatory proteins. They include the proteasome in Eukaryotes, Archaea, and Actinomycetales and the HslVU (ClpQY, clpXP) complex in other eubacteria. Genes homologues to eubacterial HslU (ClpY, clpX) have also been demonstrated in to be present in the genome of trypanosomatid protozoa
[1]
.

The proteasome (or macropain) (
3.4.25.1
)
[2, 3, 4, 5, 6]
is a multicatalytic proteinase complex in eukaryotes and archaea, and in some bacteria, that is involved in an ATP/ubiquitin-dependent non-lysosomal proteolytic pathway. In eukaryotes the 20S proteasome is composed of 28 distinct subunits which form a highly ordered ring-shaped structure (20S ring) of about 700kDa. Proteasome subunits can be classified on the basis of sequence similarities into two groups, alpha (A) and beta (B). The proteasome consists of four stacked rings composed of α/β/β/α subunits. There are seven different alpha subunits and seven different beta subunits
[9]
. Three of the seven beta subunits are peptidases, each with a different specificity. Subunit beta1c (MEROPS identifier T01.010) has a preference for cleaving glutaminyl bonds ("peptidyl-glutamyl-like" or "caspase-like"), subunit beta2c (MEROPS identifier T01.011) has a preference for cleaving arginyl and lysyl bonds ("trypsin-like"), and subunit beta5c (MEROPS identifier T01.012) cleaves after hydrophobic amino acids ("chymotrypsin-like")
[10]
. The proteasome subunits are related to N-terminal nucleophile hydrolases, and the catalytic subunits have an N-terminal threonine nucleophile.

The prokaryotic ATP-dependent proteasome is coded for by the heat-shock locus VU (HslVU). It consists of HslV, a peptidase, and HslU (
IPR004491
), the ATPase and chaperone belonging to the AAA/Clp/Hsp100 family. The crystal structure of Thermotoga maritima HslV has been determined to 2.1-A resolution. The structure of the dodecameric enzyme is well conserved compared to those from Escherichia coli and Haemophilus influenzae
[7, 8]
.

This entry contains threonine peptidases and non-peptidase homologues belong to MEROPS peptidase family T1 (proteasome family, clan PB(T)). The family consists of the protease components of the archaeal and bacterial proteasomes and the alpha and beta subunits of the eukaryotic proteasome.

References

1.Eubacterial HslV and HslU subunits homologs in primordial eukaryotes. Couvreur B, Wattiez R, Bollen A, Falmagne P, Le Ray D, Dujardin JC. Mol. Biol. Evol. 19, 2110-7, (2002). View articlePMID: 12446803

2.Proteasomes: multicatalytic proteinase complexes. Rivett AJ. Biochem. J. 291 ( Pt 1), 1-10, (1993). View articlePMID: 7682410

3.The multicatalytic proteinase of mammalian cells. Rivett AJ. Arch. Biochem. Biophys. 268, 1-8, (1989). View articlePMID: 2643381

4.Proteolysis, proteasomes and antigen presentation. Goldberg AL, Rock KL. Nature 357, 375-9, (1992). View articlePMID: 1317508

5.Proteasomes. Multicatalytic proteinase complexes. Wilk S. Enzyme Protein 47, 187-8, (1993). PMID: 7697118

6.Proteasomes: destruction as a programme. Hilt W, Wolf DH. Trends Biochem. Sci. 21, 96-102, (1996). View articlePMID: 8882582

7.Isolation and characterization of the prokaryotic proteasome homolog HslVU (ClpQY) from Thermotoga maritima and the crystal structure of HslV. Song HK, Bochtler M, Azim MK, Hartmann C, Huber R, Ramachandran R. Biophys. Chem. 100, 437-52, (2003). View articlePMID: 12646382

8.Structure and reactivity of an asymmetric complex between HslV and I-domain deleted HslU, a prokaryotic homolog of the eukaryotic proteasome. Kwon AR, Kessler BM, Overkleeft HS, McKay DB. J. Mol. Biol. 330, 185-95, (2003). View articlePMID: 12823960

9.Structure of 20S proteasome from yeast at 2.4 A resolution. Groll M, Ditzel L, Lowe J, Stock D, Bochtler M, Bartunik HD, Huber R. Nature 386, 463-71, (1997). View articlePMID: 9087403

10.Pituitary multicatalytic proteinase complex. Specificity of components and aspects of proteolytic activity. Orlowski M, Michaud C. Biochemistry 28, 9270-8, (1989). View articlePMID: 2535672

GO terms

Cross References

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