Linked Life Data

2931432

Source:http://linkedlifedata.com/resource/pubmed/id/2931432

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
22
pubmed:dateCreated
1985-10-30
pubmed:abstractText
The energy requirement for protein breakdown in Escherichia coli appears to be due to protease La, the lon gene product, which hydrolyzes proteins and ATP in a coupled process. This novel enzyme was investigated with small peptides, identified as substrates in the preceding manuscript. Although the degradation of proteins to acid-soluble material requires hydrolysis of a nucleoside triphosphate, cleavage of small fluorogenic substrates, such as glutaryl-Ala-Ala-Phe-methoxynaphthylamine, was found to require only binding of nucleotides to the enzyme. Nonhydrolyzable analogs of ATP, slowly hydrolyzed nucleotides, and even inorganic triphosphate and pyrophosphate stimulate the breakdown of these peptides but not of large proteins such as casein or serum albumin. In addition, vanadate, an inhibitor of the enzyme's ATPase activity, prevents protein degradation, but vanadate does not inhibit and can even stimulate peptide hydrolysis. Degradation of natural oligopeptides or of small polypeptides (less than 10,000 Da) also does not require hydrolysis of the nucleotide. Furthermore, although protein substrates promote ATP cleavage, the fluorogenic peptides inhibit this process. Also, no evidence was obtained for phosphorylation of the protease or of the substrate during ATP hydrolysis. These findings suggest that protein breakdown involves a cyclical series of reactions: 1) ATP binds to the protease and activates it allosterically, thus allowing peptide bond cleavage; 2) the hydrolysis of ATP must occur subsequently and should prevent further peptide bond cleavage until additional nucleoside triphosphates are bound; 3) with proteins as substrates, this reaction cycle probably occurs repeatedly until small peptides are generated.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/ATP-Dependent Proteases, http://linkedlifedata.com/resource/pubmed/chemical/Adenosine Triphosphatases, http://linkedlifedata.com/resource/pubmed/chemical/Adenosine Triphosphate, http://linkedlifedata.com/resource/pubmed/chemical/Endopeptidases, http://linkedlifedata.com/resource/pubmed/chemical/Escherichia coli Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Heat-Shock Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Lon protein, E coli, http://linkedlifedata.com/resource/pubmed/chemical/Peptides, http://linkedlifedata.com/resource/pubmed/chemical/Polyphosphates, http://linkedlifedata.com/resource/pubmed/chemical/Protease La, http://linkedlifedata.com/resource/pubmed/chemical/Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Ribonucleotides, http://linkedlifedata.com/resource/pubmed/chemical/Serine Endopeptidases
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
5
pubmed:volume
260
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
12029-34
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1985
pubmed:articleTitle
The role of ATP hydrolysis in the breakdown of proteins and peptides by protease La from Escherichia coli.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't