Aquifex aeolicus VF5 Pathway: isoleucine biosynthesis I
Inferred by computational analysis

Pathway diagram: isoleucine biosynthesis I

If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.

Locations of Mapped Genes:

Schematic showing all replicons, marked with selected genes

Synonyms: superpathway of isoleucine biosynthesis

Superclasses: BiosynthesisAmino Acids BiosynthesisProteinogenic Amino Acids BiosynthesisL-isoleucine Biosynthesis

Pathway Summary from MetaCyc:
General Background

L-isoleucine is almost always synthesized from 2-oxobutanoate. In the most common pathway, 2-oxobutanoate is generated from L-aspartate via L-threonine (this pathway). The key enzyme in this pathway is threonine deaminase, encoded by the ilvA gene.

In addition to the standard pathway, microorganisms have developed several alternative pathways for L-isoleucine biosynthesis. 2-oxobutanoate can be synthesized from L-glutamate via (2S, 3S)-3-methylaspartate (see L-isoleucine biosynthesis III) [Phillips72], from pyruvate (see L-isoleucine biosynthesis II) [Vollbrecht74, Charon74, Xu04], and by carboxylation of propanoate (see L-isoleucine biosynthesis IV) [Buchanan69, Sauer75, Eikmanns83]). In addition, there are several reports that some anaerobic bacteria can carboxylate 2-methylbutanoate to L-isoleucine via (S)-3-methyl-2-oxopentanoate (see L-isoleucine biosynthesis V) [Robinson69, Monticello84, Allison84].

Subpathways: isoleucine biosynthesis I (from threonine), threonine biosynthesis from homoserine, homoserine biosynthesis, aspartate biosynthesis

Pathway Evidence Glyph:

Pathway evidence glyph

This organism is in the expected taxonomic range for this pathway.

Key to pathway glyph edge colors:

  An enzyme catalyzing this reaction is present in this organism
  No enzyme catalyzing this reaction has been identified in this organism
  The reaction is unique to this pathway in MetaCyc
  Represents spontaneous reactions, or lines that do not represent reactions (e.g. in polymerization pathways)

Created in MetaCyc 03-Mar-2005 by Caspi R, SRI International
Imported from MetaCyc 08-Aug-2014 by Subhraveti P, SRI International


Allison84: Allison MJ, Baetz AL, Wiegel J (1984). "Alternative pathways for biosynthesis of leucine and other amino acids in Bacteroides ruminicola and Bacteroides fragilis." Appl Environ Microbiol 48(6);1111-7. PMID: 6440485

Buchanan69: Buchanan BB (1969). "Role of ferredoxin in the synthesis of alpha-ketobutyrate from propionyl coenzyme A and carbon dioxide by enzymes from photosynthetic and nonphotosynthetic bacteria." J Biol Chem 244(15);4218-23. PMID: 5800441

Charon74: Charon NW, Johnson RC, Peterson D (1974). "Amino acid biosynthesis in the spirochete Leptospira: evidence for a novel pathway of isoleucine biosynthesis." J Bacteriol 117(1);203-11. PMID: 4808901

Eikmanns83: Eikmanns, B., Jaenchen, R., Thauer, R. K. (1983). "Propionate assimilation by methanogenic bacteria." Arch. Microbiol. 136:106-110.

Monticello84: Monticello DJ, Hadioetomo RS, Costilow RN (1984). "Isoleucine synthesis by Clostridium sporogenes from propionate or alpha-methylbutyrate." J Gen Microbiol 130(2);309-18. PMID: 6726176

Phillips72: Phillips AT, Nuss JI, Moosic J, Foshay C (1972). "Alternate pathway for isoleucine biosynthesis in Escherichia coli." J Bacteriol 109(2);714-9. PMID: 4550817

Robinson69: Robinson IM, Allison MJ (1969). "Isoleucine biosynthesis from 2-methylbutyric acid by anaerobic bacteria from the rumen." J Bacteriol 97(3);1220-6. PMID: 5813342

Sauer75: Sauer FD, Erfle JD, Mahadevan S (1975). "Amino acid biosynthesis in mixed rumen cultures." Biochem J 150(3);357-72. PMID: 1212197

Vollbrecht74: Vollbrecht D (1974). "Three pathways of isoleucine biosynthesis in mutant strains of Saccharomyces cerevisiae." Biochim Biophys Acta 362(2);382-9. PMID: 4607875

Xu04: Xu, H., Zhang, Y., Guo, X., Ren, S., Staempfli, A.A., Chiao, J., Jiang, W., Zhao, G. (2004). "Isoleucine biosynthesis in Leptospira interrogans serotype lai strain 56601 proceeds via a threonine-independent pathway." J. Bacteriol. 186(16):5400-5409. PMID: 15292141

Other References Related to Enzymes, Genes, Subpathways, and Substrates of this Pathway

Latendresse13: Latendresse M. (2013). "Computing Gibbs Free Energy of Compounds and Reactions in MetaCyc."

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Page generated by Pathway Tools version 20.0 (software by SRI International) on Thu May 5, 2016, BIOCYC13A.