Publication Date:
1995-04-28
Description:
The three-dimensional structure of the proteasome from the archaebacterium Thermoplasma acidophilum has been elucidated by x-ray crystallographic analysis by means of isomorphous replacement and cyclic averaging. The atomic model was built and refined to a crystallographic R factor of 22.1 percent. The 673-kilodalton protease complex consists of 14 copies of two different subunits, alpha and beta, forming a barrel-shaped structure of four stacked rings. The two inner rings consist of seven beta subunits each, and the two outer rings consist of seven alpha subunits each. A narrow channel controls access to the three inner compartments. The alpha 7 beta 7 beta 7 alpha 7 subunit assembly has 72-point group symmetry. The structures of the alpha and beta subunits are similar, consisting of a core of two antiparallel beta sheets that is flanked by alpha helices on both sides. The binding of a peptide aldehyde inhibitor marks the active site in the central cavity at the amino termini of the beta subunits and suggests a novel proteolytic mechanism.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lowe, J -- Stock, D -- Jap, B -- Zwickl, P -- Baumeister, W -- Huber, R -- New York, N.Y. -- Science. 1995 Apr 28;268(5210):533-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max-Planck-Institut fur Biochemie, Abteilung fur Strukturforschung, Martinsried, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7725097" target="_blank"〉PubMed〈/a〉
Keywords:
Amino Acid Sequence
;
Archaeal Proteins
;
Binding Sites
;
Chaperonin 60/chemistry
;
Computer Graphics
;
Crystallography, X-Ray
;
Cysteine Endopeptidases/*chemistry/metabolism
;
Endopeptidases/*chemistry/metabolism
;
Fourier Analysis
;
Hydrogen Bonding
;
Leupeptins/chemistry/metabolism
;
*Models, Molecular
;
Molecular Sequence Data
;
Multienzyme Complexes/*chemistry/metabolism
;
Protease Inhibitors/chemistry/metabolism
;
Proteasome Endopeptidase Complex
;
Protein Conformation
;
Protein Folding
;
Protein Structure, Secondary
;
Proteins/metabolism
;
Thermoplasma/*enzymology
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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