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MetaCyc Pathway: homogalacturonan degradation
Inferred from experiment

Enzyme View:

Pathway diagram: homogalacturonan degradation

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.

Synonyms: pectin degradation

Superclasses: Degradation/Utilization/AssimilationCarbohydrates DegradationSugars Degradation

Some taxa known to possess this pathway include : Actinidia deliciosa, Arabidopsis thaliana col, Brassica napus, Chamaecyparis obtusa, Citrus sinensis, Cryptomeria japonica, Daucus carota, Gossypium barbadense, Gossypium hirsutum, Malus domestica, Medicago sativa, Nicotiana tabacum, Persea americana, Solanum lycopersicum, Vitis vinifera

Expected Taxonomic Range: Embryophyta

Homogalacturonan (HGA) is a linear chain of 1,4-linked a-D-galacturonic acid residues in which some of the carboxyl groups are methyl esterified. HGA accounts for up to 60% of the pectin found in primary cell walls of all plants. The pectin network is systematically disassembled during many stages of plant development, especially those that require cell separation including fruit ripening, organ abscission, pod and anther dehiscence, and pollen grain maturation. Two major steps are involved in the homogalacturonan disassembling process that requires a methylesterase and a polygalacturonase. The methylesterase prepares deesterified domains of homogalacturonan that can become suitable for the action of polygalacturonase and other pectinolytic enzymes. The deesterified domains of homogalacturonan can also be cross-linked with calcium, resulting in gel formation which contributes to intercellular adhesion.

Citations: [Willats01, Johansson02b, Hadfield98 , Zheng92a]

Unification Links: AraCyc:PWY-1081

Reviewed 28-May-2009 by Pujar A, Boyce Thompson Institute


Hadfield98: Hadfield KA, Bennett AB (1998). "Polygalacturonases: many genes in search of a function." Plant Physiol 117(2);337-43. PMID: 9625687

Johansson02b: Johansson K, El-Ahmad M, Friemann R, Jornvall H, Markovic O, Eklund H (2002). "Crystal structure of plant pectin methylesterase." FEBS Lett 514(2-3);243-9. PMID: 11943159

Willats01: Willats WG, McCartney L, Mackie W, Knox JP (2001). "Pectin: cell biology and prospects for functional analysis." Plant Mol Biol 47(1-2);9-27. PMID: 11554482

Zheng92a: Zheng L, Heupel RC, DellaPenna D (1992). "The beta subunit of tomato fruit polygalacturonase isoenzyme 1: isolation, characterization, and identification of unique structural features." Plant Cell 4(9);1147-56. PMID: 1392611

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

Arias02: Arias CR, Burns JK (2002). "A pectinmethylesterase gene associated with a heat-stable extract from citrus." J Agric Food Chem 50(12);3465-72. PMID: 12033812

Atkinson94a: Atkinson RG (1994). "A cDNA clone for endopolygalacturonase from apple." Plant Physiol 105(4);1437-8. PMID: 7972500

Dean88: Dean DellaPenna, Alan B. Bennett "In vitro synthesis and processing of tomato fruit polygalacturonase." Plant Physiology, 1988, 86:1057-1063.

Hall94: Hall LN, Bird CR, Picton S, Tucker GA, Seymour GB, Grierson D (1994). "Molecular characterisation of cDNA clones representing pectin esterase isozymes from tomato." Plant Mol Biol 25(2);313-8. PMID: 8018878

Kutsunai93: Kutsunai SY, Lin AC, Percival FW, Laties GG, Christoffersen RE (1993). "Ripening-related polygalacturonase cDNA from avocado." Plant Physiol 103(1);289-90. PMID: 8208850

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

Lester94: Lester DR, Speirs J, Orr G, Brady CJ (1994). "Peach (Prunus persica) endopolygalacturonase cDNA isolation and mRNA analysis in melting and nonmelting peach cultivars." Plant Physiol 105(1);225-31. PMID: 8029352

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by Pathway Tools version 19.5 (software by SRI International) on Tue May 3, 2016, biocyc13.