MetaCyc Pathway: L-proline biosynthesis III
Inferred from experiment

Enzyme View:

Pathway diagram: L-proline biosynthesis III

This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.

Superclasses: BiosynthesisAmino Acids BiosynthesisProteinogenic Amino Acids BiosynthesisL-proline Biosynthesis

Some taxa known to possess this pathway include : Arabidopsis thaliana col, Hordeum vulgare, Nicotiana tabacum, Vigna aconitifolia

Expected Taxonomic Range: Viridiplantae

In addition to be a major constituent of proteins, proline also acts as an osmotic protectant in bacteria, plants and animals that are under osmotic stress. In Arabidopsis, proline can account for up to 20% of the free amino acid pool after salt stress [Verbruggen93]. There are two alternative routes in proline biosynthesis in higher plants: the ornithine and the glutamate pathways. It is also known that, as in plants, both ornithine and glutamate are precursors of proline biosynthesis in microorganisms and mammals. The plant glutamate pathway differs from that in bacteria and human. In bacteria and human, the conversion of glutamate to glutamate-5-semialdehyde (GSA) is catalyzed by two enzymes via two consecutive reactions, whereas, in higher plants the conversion is catalyzed by a bi-functional enzyme in a single reaction [Hu92]. Many research activities have been devoted to understand the relative contributions of the two alternative pathways to the increased proline accumulations under stress. Measurement of free proline content and gene expression and enzyme activity levels from salt-stress treated plants [Roosens98] showed that in young Arabidopsis plants, both the ornithine and the glutamate pathways contribute to the increase of proline level during osmotic stress, whereas, in adult plants, only the glutamate pathway plays an important role in proline accumulation. The decreased ornithine aminotransferase (OAT) and increased pyrroline-5-carboxylate synthetase (P5CS) transcripts level in salt-stressed month bean plants suggested that the glutamate pathway is the major contributor in proline accumulation upon osmotic stress [Delauney93]. The same study also found that the glutamate pathway is upregulated under nitrogen limitation, whereas, the ornithine pathway is prominent under high nitrogen input. Studies of transcripts level of P5CS and OAT and their correlations with the free proline content in Medicago, however, suggested that both the ornithine and the glutamate pathways contribute to the osmotic stress-induced proline accumulation [Armengaud04].

Abscisic acid (ABA) and salt stress stimulate proline biosynthesis in plants [Abraham03]. On the other hand, phospholipase D (PLD) was shown a negative regulator of proline biosynthesis in Arabidopsis thaliana [Thiery04].

The first reaction catalyzed by P5CS is the rate-limiting step. P5CS is primarily regulated at the transcriptional level [Strizhov97].

Variants: L-arginine degradation VI (arginase 2 pathway), L-ornithine degradation I (L-proline biosynthesis), L-proline biosynthesis I, L-proline biosynthesis II (from arginine), L-proline biosynthesis IV

Unification Links: AraCyc:PWY-3341


Abraham03: Abraham E, Rigo G, Szekely G, Nagy R, Koncz C, Szabados L (2003). "Light-dependent induction of proline biosynthesis by abscisic acid and salt stress is inhibited by brassinosteroid in Arabidopsis." Plant Mol Biol 51(3);363-72. PMID: 12602867

Armengaud04: Armengaud P, Thiery L, Buhot N, Grenier-De March G, Savoure A (2004). "Transcriptional regulation of proline biosynthesis in Medicago truncatula reveals developmental and environmental specific features." Physiol Plant 120(3);442-450. PMID: 15032841

Delauney93: Delauney AJ, Hu CA, Kishor PB, Verma DP (1993). "Cloning of ornithine delta-aminotransferase cDNA from Vigna aconitifolia by trans-complementation in Escherichia coli and regulation of proline biosynthesis." J Biol Chem 268(25);18673-8. PMID: 8103048

Hu92: Hu CA, Delauney AJ, Verma DP (1992). "A bifunctional enzyme (delta 1-pyrroline-5-carboxylate synthetase) catalyzes the first two steps in proline biosynthesis in plants." Proc Natl Acad Sci U S A 89(19);9354-8. PMID: 1384052

Roosens98: Roosens NH, Thu TT, Iskandar HM, Jacobs M (1998). "Isolation of the ornithine-delta-aminotransferase cDNA and effect of salt stress on its expression in Arabidopsis thaliana." Plant Physiol 117(1);263-71. PMID: 9576796

Strizhov97: Strizhov N, Abraham E, Okresz L, Blickling S, Zilberstein A, Schell J, Koncz C, Szabados L (1997). "Differential expression of two P5CS genes controlling proline accumulation during salt-stress requires ABA and is regulated by ABA1, ABI1 and AXR2 in Arabidopsis." Plant J 12(3);557-69. PMID: 9351242

Thiery04: Thiery L, Leprince AS, Lefebvre D, Ghars MA, Debarbieux E, Savoure A (2004). "Phospholipase D is a negative regulator of proline biosynthesis in Arabidopsis thaliana." J Biol Chem 279(15);14812-8. PMID: 14742440

Verbruggen93: Verbruggen N, Villarroel R, Van Montagu M (1993). "Osmoregulation of a pyrroline-5-carboxylate reductase gene in Arabidopsis thaliana." Plant Physiol 103(3);771-81. PMID: 8022935

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

Baich69: Baich A (1969). "Proline synthesis in Escherichia coli. A proline-inhibitable glutamic acid kinase." Biochim Biophys Acta 1969;192(3);462-7. PMID: 4904678

Baich71: Baich A (1971). "The biosynthesis of proline in Escherichia coli: phosphate-dependent glutamate -semialdehyde dehydrogenase (NADP), the second enzyme in the pathway." Biochim Biophys Acta 244(1);129-34. PMID: 4399189

Bairoch93a: Bairoch A, Boeckmann B (1993). "The SWISS-PROT protein sequence data bank, recent developments." Nucleic Acids Res. 21:3093-3096. PMID: 8332529

Baumgartner00: Baumgartner MR, Hu CA, Almashanu S, Steel G, Obie C, Aral B, Rabier D, Kamoun P, Saudubray JM, Valle D (2000). "Hyperammonemia with reduced ornithine, citrulline, arginine and proline: a new inborn error caused by a mutation in the gene encoding delta(1)-pyrroline-5-carboxylate synthase." Hum Mol Genet 9(19);2853-8. PMID: 11092761

BRENDA14: BRENDA team (2014). Imported from BRENDA version existing on Aug 2014.

BSUB93: "Bacillus subtilis and Other Gram-Positive Bacteria: Biochemistry, Physiology, and Molecular Genetics." (1993). Editors: Sonenshein, A.L., Hoch, J.A., Losick, R. American Society For Microbiology, Washington, DC.

Canas08: Canas RA, Villalobos DP, Diaz-Moreno SM, Canovas FM, Canton FR (2008). "Molecular and functional analyses support a role of Ornithine-{delta}-aminotransferase in the provision of glutamate for glutamine biosynthesis during pine germination." Plant Physiol 148(1);77-88. PMID: 18621980

Csonka88: Csonka LN, Gelvin SB, Goodner BW, Orser CS, Siemieniak D, Slightom JL (1988). "Nucleotide sequence of a mutation in the proB gene of Escherichia coli that confers proline overproduction and enhanced tolerance to osmotic stress." Gene 1988;64(2);199-205. PMID: 2841193

Deutch01: Deutch CE, Klarstrom JL, Link CL, Ricciardi DL (2001). "Oxidation of L-thiazolidine-4-carboxylate by delta1-pyrroline-5-carboxylate reductase in Escherichia coli." Curr Microbiol 42(6);442-6. PMID: 11381339

Deutch82: Deutch AH, Smith CJ, Rushlow KE, Kretschmer PJ (1982). "Escherichia coli delta 1-pyrroline-5-carboxylate reductase: gene sequence, protein overproduction and purification." Nucleic Acids Res 1982;10(23);7701-14. PMID: 6296787

Funck08: Funck D, Stadelhofer B, Koch W (2008). "Ornithine-delta-aminotransferase is essential for arginine catabolism but not for proline biosynthesis." BMC Plant Biol 8;40. PMID: 18419821

Gardan95: Gardan R, Rapoport G, Debarbouille M (1995). "Expression of the rocDEF operon involved in arginine catabolism in Bacillus subtilis." J Mol Biol 1995;249(5);843-56. PMID: 7540694

Gardan97: Gardan R, Rapoport G, Debarbouille M (1997). "Role of the transcriptional activator RocR in the arginine-degradation pathway of Bacillus subtilis." Mol Microbiol 1997;24(4);825-37. PMID: 9194709

Hayzer81: Hayzer DJ, Leisinger T (1981). "Proline biosynthesis in Escherichia coli. Stoichiometry and end-product identification of the reaction catalysed by glutamate semialdehyde dehydrogenase." Biochem J 197(2);269-74. PMID: 7034716

Hayzer82: Hayzer DJ, Leisinger T (1982). "Proline biosynthesis in Escherichia coli. Purification and characterisation of glutamate-semialdehyde dehydrogenase." Eur J Biochem 1982;121(3);561-5. PMID: 7035170

Hayzer83: Hayzer DJ, Leisinger T (1983). "Proline biosynthesis in Escherichia coli. Kinetic and mechanistic properties of glutamate semialdehyde dehydrogenase." Biochim Biophys Acta 742(2);391-8. PMID: 6337636

Hill67: Hill DL, Chambers P (1967). "The biosynthesis of proline by Tetrahymena pyriformis." Biochim Biophys Acta 148(2);435-47. PMID: 6075416

Hu99: Hu CA, Lin WW, Obie C, Valle D (1999). "Molecular enzymology of mammalian Delta1-pyrroline-5-carboxylate synthase. Alternative splice donor utilization generates isoforms with different sensitivity to ornithine inhibition." J Biol Chem 274(10);6754-62. PMID: 10037775

Kenklies99: Kenklies J, Ziehn R, Fritsche K, Pich A, Andreesen JR (1999). "Proline biosynthesis from L-ornithine in Clostridium sticklandii: purification of delta1-pyrroline-5-carboxylate reductase, and sequence and expression of the encoding gene, proC." Microbiology 1999;145 ( Pt 4);819-26. PMID: 10220161

Krueger86: Krueger, Rolf, Jager, Hans-jurgen, Hintz, Martin, Pahlich, Edwin "Purification to homogeneity of pyrroline-5-carboxylate reductase from barley." Plant Physiology (1986), vol 80, 142-144.

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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