Linked Life Data

9642094

Source:http://linkedlifedata.com/resource/pubmed/id/9642094

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1998-7-31
pubmed:abstractText
The proteasome is the central enzyme of protein degradation in the cytosol and the nucleus. It is involved in the removal of abnormal, misfolded or incorrectly assembled proteins, in the processing or degradation of transcriptional regulators in stress response, in degradation of cyclins in cell-cycle control, in the destruction of transcription factors or metabolic enzymes in cell differentiation and metabolic response, and in MHC class I mediated cellular immune response. By the analysis of the crystal and molecular structures of the 20 S proteasomes from the archaeon Thermoplasma acidophilum and from yeast it was shown that the beta-type subunits in which the proteolytic activities reside are members of the N-terminal nucleophile (Ntn) protein family. They are synthesized as proproteins and become active by autoprocessing at a Gly-1-Thr1 bond. The Thr1Ala mutant of subunit beta1/Pre3 of the 20 S proteasome from yeast is unable to autolyse. Its crystal and molecular structure at 2.2 A resolution described here shows that the pro-segment adopts a well-defined gamma-turn conformation at Gly-1 and provides a first view at an autolysis site in Ntn hydrolases. The Gly-1 carbonyl oxygen displays two hydrogen bonds. The modelled Thr1 side-chain is located above the gamma-turn bulge such that addition of its nucleophilic hydroxyl group to the electrophilic Gly-1 carbonyl carbon atom may proceed by very small motions. The pro-segment binding site and the catalytic site provide a rigid structural framework and appropriate hydrogen bond donors for this reaction. The same structure also supports addition of the Thr1 hydroxyl group to the carbonyl carbon atom of Leu-2 as a model for the first step in substrate hydrolysis by the proteasome.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0022-2836
pubmed:author
pubmed:copyrightInfo
Copyright 1998 Academic Press.
pubmed:issnType
Print
pubmed:day
26
pubmed:volume
279
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1187-91
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Conformational constraints for protein self-cleavage in the proteasome.
pubmed:affiliation
Max-Planck-Institut für Biochemie, Martinsried, D-82152, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't