Q9V2V6 (PSA1_HALVD) Reviewed, UniProtKB/Swiss-Prot
Last modified June 11, 2014. Version 85. History...
Names and origin
|Protein names||Recommended name:|
Proteasome subunit alpha 1
20S proteasome alpha subunit 1
Proteasome core protein PsmA 1
Cleaved into the following chain:
|Organism||Haloferax volcanii (strain ATCC 29605 / DSM 3757 / JCM 8879 / NBRC 14742 / NCIMB 2012 / VKM B-1768 / DS2) (Halobacterium volcanii) [Reference proteome] [HAMAP]|
|Taxonomic identifier||309800 [NCBI]|
|Taxonomic lineage||Archaea › Euryarchaeota › Halobacteria › Halobacteriales › Halobacteriaceae › Haloferax ›|
|Sequence length||252 AA.|
|Sequence processing||The displayed sequence is further processed into a mature form.|
|Protein existence||Evidence at protein level|
General annotation (Comments)
Component of the proteasome core, a large protease complex with broad specificity involved in protein degradation. The H.volcanii alpha1-beta proteasome is able to cleave oligopeptides after Phe, Tyr and Trp, poorly after Glu but not after Arg. Thus, displays chymotrypsin-like activity, low caspase-like activity but no trypsin-like activity. Ref.1
Cleavage of peptide bonds with very broad specificity. Ref.1
The formation of the proteasomal ATPase PAN-20S proteasome complex, via the docking of the C-termini of PAN into the intersubunit pockets in the alpha-rings, triggers opening of the gate for substrate entry. Interconversion between the open-gate and close-gate conformations leads to a dynamic regulation of the 20S proteasome proteolysis activity By similarity. In vitro, the chymotrypsin-like activity of the alpha1-beta proteasome is potently inhibited by carbobenzoxyl-leucinyl-leucinyl-leucinal-H (MG132) and significantly by N-acetyl-leucinyl-leucinyl-norleucinal-H (calpain inhibitor I). Ref.1
The 20S proteasome core is composed of 14 alpha and 14 beta subunits that assemble into four stacked heptameric rings, resulting in a barrel-shaped structure. The two inner rings, each composed of seven catalytic beta subunits, are sandwiched by two outer rings, each composed of seven alpha subunits. H.volcanii produces at least 2 types of 20S proteasomes: an alpha1-beta proteasome and a proteasome containing all three subunits (alpha1, alpha2, and beta) that appears to be asymmetrical with homo-oligomeric alpha1 and alpha2 rings positioned on separate ends. The catalytic chamber with the active sites is on the inside of the barrel. Has probably a gated structure, the ends of the cylinder being occluded by the N-termini of the alpha-subunits. Is likely capped at one or both ends by the proteasome regulatory ATPase, PAN. Ref.1 Ref.3
Up-regulated at the mRNA level during transition from exponential to stationary phase. However, at the protein level, PsmA 1 is expressed at a high and relatively constant level throughout growth. Ref.1 Ref.4
Strains lacking psmA1 gene alone display relatively normal growth rate and overall cell yield, but they are more sensitive to growth on organic versus inorganic nitrogen sources and hypo-osmotic stress, and they show limited growth in the presence of L-canavanine. Abolition of alpha1 subunit synthesis also has a severe impact on the ability of cells to withstand thermal stress. Moreover, depletion of psmA1 and psmA2 together renders the cells inviable. Ref.6
H.volcanii proteasome requires high concentrations of salt, similar to the extracellular environment and cytoplasm of this organism, for complex stability and optimal activity.
Belongs to the peptidase T1A family.
Optimum pH is 7.0-9.3 for the Suc-LLVY-Amc hydrolyzing activity (with the alpha1-beta proteasome subtype). Ref.1
Optimum temperature is 75 degrees Celsius for the Suc-LLVY-Amc hydrolyzing activity (with the alpha1-beta proteasome subtype).
|Technical term||Complete proteome|
Direct protein sequencing
|Gene Ontology (GO)|
|Biological_process||proteasomal protein catabolic processubiquitin-dependent protein catabolic process|
Inferred from electronic annotation. Source: InterPro
Inferred from electronic annotation. Source: UniProtKB-SubCellproteasome core complex, alpha-subunit complex
|Molecular_function||endopeptidase activitythreonine-type endopeptidase activity|
Inferred from electronic annotation. Source: UniProtKB-KW
|Complete GO annotation...|
Sequence annotation (Features)
|Feature key||Position(s)||Length||Description||Graphical view||Feature identifier|
|Chain||1 – 252||252||Proteasome subunit alpha 1 HAMAP-Rule MF_00289||PRO_0000124171|
|Initiator methionine||1||1||Removed; alternate Ref.5|
|Chain||2 – 252||251||Proteasome subunit alpha 1, N-terminally processed HAMAP-Rule MF_00289||PRO_0000397604|
Amino acid modifications
|Modified residue||1||1||N-acetylmethionine; alternate Ref.5|
|Mutagenesis||2 – 12||11||Missing: Prevents acetylation of Met-1. Enhances peptidase activity of the proteasome. Renders the cells less tolerant of hypoosmotic stress than the wild-type. Ref.7|
|Mutagenesis||2||1||Q → A: Enhances cleavage of PsmA1 by methionine aminopeptidase (MAP), resulting in acetylation of the N-terminal alanine. Enhances peptidase activity of the proteasome. Renders the cells less tolerant of hypoosmotic stress than the wild-type. Ref.7|
|Mutagenesis||2||1||Q → D, P or T: Does not alter the prevalence of the alpha1 subunit in N-acetylated form in proteasomes. Renders the cells more tolerant of hypoosmotic and high-temperature stress than the wild-type. Ref.7|
|Sequence conflict||96||1||R → H in AAD53404. Ref.1|
|||"Halophilic 20S proteasomes of the archaeon Haloferax volcanii: purification, characterization, and gene sequence analysis."|
Wilson H.L., Aldrich H.C., Maupin-Furlow J.
J. Bacteriol. 181:5814-5824(1999) [PubMed] [Europe PMC] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA], PROTEIN SEQUENCE OF 23-30; 89-95 AND 150-163, BLOCKAGE OF N-TERMINUS, FUNCTION, CATALYTIC ACTIVITY, SUBSTRATE SPECIFICITY, BIOPHYSICOCHEMICAL PROPERTIES, ENZYME REGULATION, SALT REQUIREMENT, SUBUNIT.
|||"The complete genome sequence of Haloferax volcanii DS2, a model archaeon."|
Hartman A.L., Norais C., Badger J.H., Delmas S., Haldenby S., Madupu R., Robinson J., Khouri H., Ren Q., Lowe T.M., Maupin-Furlow J., Pohlschroder M., Daniels C., Pfeiffer F., Allers T., Eisen J.A.
PLoS ONE 5:E9605-E9605(2010) [PubMed] [Europe PMC] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
Strain: ATCC 29605 / DSM 3757 / JCM 8879 / NBRC 14742 / NCIMB 2012 / VKM B-1768 / DS2.
|||"Subunit topology of two 20S proteasomes from Haloferax volcanii."|
Kaczowka S.J., Maupin-Furlow J.A.
J. Bacteriol. 185:165-174(2003) [PubMed] [Europe PMC] [Abstract]
Cited for: SUBUNIT.
|||"Differential regulation of the PanA and PanB proteasome-activating nucleotidase and 20S proteasomal proteins of the haloarchaeon Haloferax volcanii."|
Reuter C.J., Kaczowka S.J., Maupin-Furlow J.A.
J. Bacteriol. 186:7763-7772(2004) [PubMed] [Europe PMC] [Abstract]
Cited for: INDUCTION.
|||"Posttranslational modification of the 20S proteasomal proteins of the archaeon Haloferax volcanii."|
Humbard M.A., Stevens S.M. Jr., Maupin-Furlow J.A.
J. Bacteriol. 188:7521-7530(2006) [PubMed] [Europe PMC] [Abstract]
Cited for: ACETYLATION AT MET-1, CLEAVAGE OF INITIATOR METHIONINE.
|||"Proteasomal components required for cell growth and stress responses in the haloarchaeon Haloferax volcanii."|
Zhou G., Kowalczyk D., Humbard M.A., Rohatgi S., Maupin-Furlow J.A.
J. Bacteriol. 190:8096-8105(2008) [PubMed] [Europe PMC] [Abstract]
Cited for: DISRUPTION PHENOTYPE.
|||"The N-terminal penultimate residue of 20S proteasome alpha1 influences its N(alpha) acetylation and protein levels as well as growth rate and stress responses of Haloferax volcanii."|
Humbard M.A., Zhou G., Maupin-Furlow J.A.
J. Bacteriol. 191:3794-3803(2009) [PubMed] [Europe PMC] [Abstract]
Cited for: ACETYLATION, MUTAGENESIS OF GLN-2 AND 2-GLN--ARG-12.
|AF126260 Genomic DNA. Translation: AAD53404.1.|
CP001956 Genomic DNA. Translation: ADE04430.1.
|RefSeq||YP_003535146.1. NC_013967.1. |
3D structure databases
Protocols and materials databases
Genome annotation databases
|EnsemblBacteria||ADE04430; ADE04430; HVO_1091. |
Enzyme and pathway databases
Family and domain databases
|Gene3D||22.214.171.124. 1 hit. |
|HAMAP||MF_00289_A. Proteasome_A_A. |
|InterPro||IPR029055. Ntn_hydrolases_N. |
|Pfam||PF00227. Proteasome. 1 hit. |
PF10584. Proteasome_A_N. 1 hit.
|SMART||SM00948. Proteasome_A_N. 1 hit. |
|SUPFAM||SSF56235. SSF56235. 1 hit. |
|TIGRFAMs||TIGR03633. arc_protsome_A. 1 hit. |
|PROSITE||PS00388. PROTEASOME_ALPHA_1. 1 hit. |
PS51475. PROTEASOME_ALPHA_2. 1 hit.
|Accession||Primary (citable) accession number: Q9V2V6|
Secondary accession number(s): D4GW11
|Entry status||Reviewed (UniProtKB/Swiss-Prot)|
|Annotation program||Prokaryotic Protein Annotation Program|