α-Keto Acid Chain Elongation Reactions Involved in the Biosynthesis of Coenzyme B (7-Mercaptoheptanoyl Threonine Phosphate) in Methanogenic Archaea†

Biochemistry ◽  
1998 ◽  
Vol 37 (28) ◽  
pp. 10108-10117 ◽  
Author(s):  
David M. Howell ◽  
Kim Harich ◽  
Huimin Xu ◽  
Robert H. White
Keyword(s):  
Methanogenic Archaea ◽  
Chain Elongation ◽  
Keto Acid ◽  
Coenzyme B ◽  
Threonine Phosphate

Growth of Paracoccus denitrificans on [2, 3- 13 C]succinate and [1, 4- 13 C]succinate - II. Isoleucine biosynthesis

1987 ◽  
Vol 231 (1264) ◽  
pp. 349-358 ◽  
Keyword(s):  
Mass Spectrometry ◽  
Paracoccus Denitrificans ◽  
Growth Conditions ◽  
Chain Elongation ◽  
Keto Acid ◽  
Isoleucine Biosynthesis

Paracoccus denitrificans was grown on either [2, 3- 13 C]succinate or [1, 4- 13 C]succinate, and extracts were analysed by using gas chroma­tography-mass spectrometry. The distribution of label in isoleucine indicated that the 2-ketobutyrate required for isoleucine biosynthesis was mainly produced from pyruvate by 2-keto-acid chain elongation (i. e. the 'pyruvate elongation pathway’). Approximately 10% of isoleucine was produced by a second pathway involving propionyl CoA. Threonine and glutamate were not utilized by P. denitrificans as a source of 2-ketobutyrate production for isoleucine biosynthesis under the growth conditions used.

scholarly journals Studies of the CobA-Type ATP:Co(I)rrinoid Adenosyltransferase Enzyme of Methanosarcina mazei Strain Gö1

2006 ◽  
Vol 188 (10) ◽  
pp. 3543-3550 ◽  
Author(s):  
Nicole R. Buan ◽  
Kimberly Rehfeld ◽  
Jorge C. Escalante-Semerena
Keyword(s):  
Biochemical Analysis ◽  
Methanogenic Archaea ◽  
Striking Difference ◽  
Resonance Spectroscopy ◽  
Gene Encoding ◽  
Reading Frame ◽  
Methanosarcina Mazei ◽  
Coenzyme B ◽  
Better Than

ABSTRACT Although methanogenic archaea use B12 extensively as a methyl carrier for methanogenesis, little is known about B12 metabolism in these prokaryotes or any other archaea. To improve our understanding of how B12 metabolism differs between bacteria and archaea, the gene encoding the ATP:co(I)rrinoid adenosyltransferase in Methanosarcina mazei strain Gö1 (open reading frame MM3138, referred to as cobAMm here) was cloned and used to restore coenzyme B12 synthesis in a Salmonella enterica strain lacking the housekeeping CobA enzyme. cobAMm protein was purified and its initial biochemical analysis performed. In vitro, the activity is enhanced 2.5-fold by the addition of Ca2+ ions, but the activity was not enhanced by Mg2+ and, unlike the S. enterica CobA enzyme, it was >50% inhibited by Mn2+. The CobA Mm enzyme had a Km ATP of 3 μM and a Km HOCbl of 1 μM. Unlike the S. enterica enzyme, CobA Mm used cobalamin (Cbl) as a substrate better than cobinamide (Cbi; a Cbl precursor); the β phosphate of ATP was required for binding to the enzyme. A striking difference between CobA Se and CobA Mm was the use of ADP as a substrate by CobA Mm , suggesting an important role for the γ phosphate of ATP in binding. The results from 31P-nuclear magnetic resonance spectroscopy experiments showed that triphosphate (PPPi) is the reaction by-product; no cleavage of PPPi was observed, and the enzyme was only slightly inhibited by pyrophosphate (PPi). The data suggested substantial variations in ATP binding and probably corrinoid binding between CobA Se and CobA Mm enzymes.

Unravelling a microbial synergy to boost caproate production via carboxylates chain elongation with ethanol

2019 ◽  
Vol 26 (2) ◽  
pp. 63-71
Author(s):  
Ling Leng ◽  
Ying Wang ◽  
Peixian Yang ◽  
Takashi Narihiro ◽  
Masaru Konishi Nobu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Microbial Consortia ◽  
Chain Elongation ◽  
Desulfovibrio Vulgaris ◽  
Rrna Gene ◽  
Selective Enrichment ◽  
Microbial Network ◽  
Cost Efficient ◽  
Rrna Gene Sequencing

Chain elongation of volatile fatty acids for medium chain fatty acids production (e.g. caproate) is an attractive approach to treat wastewater anaerobically and recover resource simultaneously. Undefined microbial consortia can be tailored to achieve chain elongation process with selective enrichment from anaerobic digestion sludge, which has advantages over pure culture approach for cost-efficient application. Whilst the metabolic pathway of the dominant caproate producer, Clostridium kluyveri, has been annotated, the role of other coexisting abundant microbiomes remained unclear. To this end, an ethanol-acetate fermentation inoculated with fresh digestion sludge at optimal conditions was conducted. Also, physiological study, thermodynamics and 16 S rRNA gene sequencing to elucidate the biological process by linking the system performance and dominant microbiomes were integrated. Results revealed a possible synergistic network in which C. kluyveri and three co-dominant species, Desulfovibrio vulgaris, Fusobacterium varium and Acetoanaerobium sticklandii coexisted. D. vulgaris and A. sticklandii (F. varium) were likely to boost the carboxylates chain elongation by stimulating ethanol oxidation and butyrate production through a syntrophic partnership with hydrogen (H2) serving as an electron messenger. This study unveils a synergistic microbial network to boost caproate production in mixed culture carboxylates chain elongation.

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