title: The biosynthesis of valine from isobutyrate by peptostreptococcus elsdenii and Bacteroides ruminicola.
abstract: 1. Growing cultures of Peptostreptococcus elsdenii and Bacteroides ruminicola incorporate (14)C from [1-(14)C]isobutyrate into the valine of cell protein. With P. elsdenii some of the (14)C is also incorporated into leucine. 2. Crude cell-free extracts of both organisms in the presence of glutamine, carbon dioxide and suitable sources of energy and electrons incorporate (14)C from [1-(14)C]isobutyrate into valine but not into leucine. 3. With extracts of P. elsdenii treated with DEAE-cellulose the reaction is dependent on ATP, CoA, thiamin pyrophosphate, molecular hydrogen and a low-potential electron carrier (ferredoxin, flavodoxin or benzyl viologen). 4. The same extracts incorporate (14)C from NaH(14)CO(3) into valine in the presence of isobutyrate plus ATP, CoA, glutamine and ferredoxin; isobutyryl-CoA or isobutyryl phosphate plus CoA will replace the isobutyrate plus CoA and ATP. With acetyl phosphate in place of isobutyryl phosphate, (14)C is incorporated into alanine. With isovalerate or 2-methylbutyrate in place of isobutyrate, (14)C is incorporated into leucine and isoleucine respectively. 5. When carrier 2-oxoisovalerate is added to the carboxylating system (14)C from [1-(14)C]isobutyrate passes into the oxo acid fraction. 6. It is concluded that these two organisms form valine from isobutyrate by the sequence isobutyrate-->isobutyryl-CoA-->2-oxoisovalerate-->valine and that the reductive carboxylation of isobutyrate is catalysed by a system similar to the pyruvate synthetase of clostridia and photosynthetic bacteria.
mesh_terms: D000255:Adenosine Triphosphate; D000409:Alanine / Q000378:metabolism; D001426:Bacterial Proteins / Q000096:biosynthesis; D001439:Bacteroides / Q000378:metabolism*; D001555:Benzene Derivatives; D001639:Bicarbonates / Q000378:metabolism; D002087:Butyrates / Q000378:metabolism*; D002245:Carbon Dioxide; D002247:Carbon Isotopes; D002848:Chromatography, DEAE-Cellulose; D002854:Chromatography, Paper; D003065:Coenzyme A; D005288:Ferredoxins; D005973:Glutamine; D006859:Hydrogen; D007202:Indicators and Reagents; D007532:Isoleucine / Q000378:metabolism; D007930:Leucine / Q000378:metabolism; D010462:Peptostreptococcus / Q000378:metabolism*; D010710:Phosphates; D014633:Valine / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D001555:Benzene Derivatives; D001639:Bicarbonates; D002087:Butyrates; D002247:Carbon Isotopes; D005288:Ferredoxins; D007202:Indicators and Reagents; D010710:Phosphates; D007532:Isoleucine; D005973:Glutamine; D002245:Carbon Dioxide; D006859:Hydrogen; D000255:Adenosine Triphosphate; D007930:Leucine; D014633:Valine; D000409:Alanine; D003065:Coenzyme A