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: fructan mobilization
|Superclasses:||Degradation/Utilization/Assimilation → Carbohydrates Degradation → Polysaccharides Degradation|
|Degradation/Utilization/Assimilation → Polymeric Compounds Degradation → Polysaccharides Degradation|
Expected Taxonomic Range: Embryophyta
Fructans are soluble linear or branched polymers of fructose that have β-2,1- or β-2,6-linkage. They are among the few abundant storage carbohydrates in plants and are accumulated in roots, tubers, bulbs, stems, leaves, and seeds. In addition to their function as storage carbohydrates, fructans may have functions involved in drought and cold tolerance. Fructans are mobilized (or degraded) to fructose in the vacuole where they were initially accumulated. In plants, the degradation of fructans is catalyzed by fructan 1-exohydrolase which hydrolyzes the β-2,1-linkages and /or fructan 6-exohydrolase which hydrolyzes the β-2,6-linkages. The released fructose re-enters cell metabolism in the cytosol.
Defoliation of grasses by grazing, mowing and cutting requires that they rejuvenate and regrow for survival. This kind of regrowth is a poorly understood phenomenon; temperate grasses which accumulate fructans, when defoliated induce the activity of fructan exohydrolases. This enzyme degrades fructans to provide the carbon source for regrowth [Tamura11].
Tamura11: Tamura KI, Sanada Y, Tase K, Komatsu T, Yoshida M (2011). "Pp6-FEH1 encodes an enzyme for degradation of highly polymerized levan and is transcriptionally induced by defoliation in timothy (Phleum pratense L.)." J Exp Bot. PMID: 21317211
Van03b: Van Den Ende W, Clerens S, Vergauwen R, Van Riet L, Van Laere A, Yoshida M, Kawakami A (2003). "Fructan 1-exohydrolases. beta-(2,1)-trimmers during graminan biosynthesis in stems of wheat? Purification, characterization, mass mapping, and cloning of two fructan 1-exohydrolase isoforms." Plant Physiol 2003;131(2);621-31. PMID: 12586886
But: But SIu, Khmelina VN, Mustakhimova II, Trotsenko IuA "[Production and characterization of Methylomicrobium alcaliphilum 20Z knockout mutants, which has sucrose and ectoin synthesis defective genes]." Mikrobiologiia 82(2);251-3. PMID: 23808151
But13: But SY, Khmelenina VN, Reshetnikov AS, Trotsenko YA (2013). "Bifunctional sucrose phosphate synthase/phosphatase is involved in the sucrose biosynthesis by Methylobacillus flagellatus KT." FEMS Microbiol Lett. PMID: 23865613
Doronina03: Doronina N, Darmaeva T, Trotsenko Y (2003). "Methylophaga natronica sp. nov., a new alkaliphilic and moderately halophilic, restricted-facultatively methylotrophic bacterium from soda lake of the Southern Transbaikal region." Syst Appl Microbiol 26(3);382-9. PMID: 14529181
Doronina03a: Doronina NV, Darmaeva TD, Trotsenko YA (2003). "Methylophaga alcalica sp. nov., a novel alkaliphilic and moderately halophilic, obligately methylotrophic bacterium from an East Mongolian saline soda lake." Int J Syst Evol Microbiol 53(Pt 1);223-9. PMID: 12656177
Reed86: Reed RH, Borowitzka LJ, Mackay MA, Chudek JA, Foster R, Warr SRC, Moore DJ, Stewart WDP (1986). "Organic solute accumulation in osmotically stressed cyanobacteria." FEMS Microbiology Letters 39(1-2);51-56.
Winter00: Winter H, Huber SC (2000). "Regulation of sucrose metabolism in higher plants: localization and regulation of activity of key enzymes." Crit Rev Biochem Mol Biol 35(4);253-89. PMID: 11005202
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