Document Detail

Pathway for isoleucine formation form pyruvate by leucine biosynthetic enzymes in leucine-accumulating isoleucine revertants of Serratia marcescens.
MedLine Citation:
PMID:  142769     Owner:  NLM     Status:  MEDLINE    
Leaky revertants isolated from isoleucine auxotrophs of Serratia marcescens mutant resistant to alpha-aminobutyric acid were previously reported to accumulate leucine in the medium, due to the absence of both feedback inhibition and repression of leucine biosynthesis. Growth of the revertant was accelerated by pyruvate, D(-)-citramalate, citraconate, and alpha-ketobutyrate, but not by threonine. Extracts of the revertant exhibited high activities of pyruvate-dependent coenzyme A liberation from acetyl-coenzyme A, hydration of citraconate, and conversion of citraconate to alpha-ketobutyrate, but showed no threonine-deaminating activity. In the leucine-accumulating revertants the above three activities were not affected by leucine, but in the wild strain and other revertants accumulating no leucine all or one of these activities was controlled by leucine. A leucine auxotroph isolated from the leucine-accumulating revertant showed isoleucine auxotrophy as well. From these data, it is concluded that, in leucine-accumulating revertants, of S. marcescent, isoleucine, is synthesized from alpha-ketobutyrate via citramalate formed from pyruvate annd acetyl-coenzyme A by leucine biosynthetic enzymes, as a result of desensitization of alpha-isopropylmalate synthetase to feedback inhibition.
M Kisumi; S Komatsubara; I Chibata
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of biochemistry     Volume:  82     ISSN:  0021-924X     ISO Abbreviation:  J. Biochem.     Publication Date:  1977 Jul 
Date Detail:
Created Date:  1977-10-31     Completed Date:  1977-10-31     Revised Date:  2007-12-19    
Medline Journal Info:
Nlm Unique ID:  0376600     Medline TA:  J Biochem     Country:  JAPAN    
Other Details:
Languages:  eng     Pagination:  95-103     Citation Subset:  IM    
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MeSH Terms
Acetyl Coenzyme A / metabolism
Butyrates / metabolism
Coenzyme A / metabolism
Isoleucine / biosynthesis*
Leucine / metabolism
Malates / metabolism
Maleates / metabolism
Pyruvates / metabolism*
Serratia marcescens / growth & development,  metabolism*
Threonine / metabolism
Valine / metabolism
Reg. No./Substance:
0/Butyrates; 0/Malates; 0/Maleates; 0/Pyruvates; 61-90-5/Leucine; 7004-03-7/Valine; 72-19-5/Threonine; 72-89-9/Acetyl Coenzyme A; 73-32-5/Isoleucine; 85-61-0/Coenzyme A

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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