Publication Date:
1995-04-28
Description:
The catalytic mechanism of the 20S proteasome from the archaebacterium Thermoplasma acidophilum has been analyzed by site-directed mutagenesis of the beta subunit and by inhibitor studies. Deletion of the amino-terminal threonine or its mutation to alanine led to inactivation of the enzyme. Mutation of the residue to serine led to a fully active enzyme, which was over ten times more sensitive to the serine protease inhibitor 3,4-dichloroisocoumarin. In combination with the crystal structure of a proteasome-inhibitor complex, the data show that the nucleophilic attack is mediated by the amino-terminal threonine of processed beta subunits. The conservation pattern of this residue in eukaryotic sequences suggests that at least three of the seven eukaryotic beta-type subunit branches should be proteolytically inactive.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Seemuller, E -- Lupas, A -- Stock, D -- Lowe, J -- Huber, R -- Baumeister, W -- New York, N.Y. -- Science. 1995 Apr 28;268(5210):579-82.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Abteilung fur Strukturbiologie Max-Planck Institut fur Biochemie, Martinsried, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7725107" target="_blank"〉PubMed〈/a〉
Keywords:
Amino Acid Sequence
;
Archaeal Proteins
;
Binding Sites
;
Coumarins/pharmacology
;
Endopeptidases/*chemistry/metabolism
;
Hydrogen-Ion Concentration
;
Molecular Sequence Data
;
Mutagenesis
;
Protein Folding
;
Sequence Alignment
;
Serine Proteinase Inhibitors/pharmacology
;
Thermoplasma/*enzymology
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
