2.02012-05-31 13:01:01 -06002015-06-03 15:53:35 -0600ECMDB00751M2MDB000183L-Threo-2-pentuloseL-Threo-2-pentulose, also called L-xylulose, is a ketopentose - a monosaccharide containing five carbon atoms, and including a ketone functional group. It has chemical formula C5H10O5. In nature it occurs in the L- and D- isomers. (Wikipedia)L-XyluloseC5H10O5150.1299150.05282343(3R,4S)-1,3,4,5-tetrahydroxypentan-2-onexylulose527-50-4OC[C@H](O)[C@@H](O)C(=O)COInChI=1S/C5H10O5/c6-1-3(8)5(10)4(9)2-7/h3,5-8,10H,1-2H2/t3-,5+/m0/s1ZAQJHHRNXZUBTE-WVZVXSGGSA-NSolidCytosolExtra-organismPeriplasmlogp-2.16logs0.65solubility6.78e+02 g/llogp-2.6pka_strongest_acidic10.57pka_strongest_basic-3iupac(3R,4S)-1,3,4,5-tetrahydroxypentan-2-oneaverage_mass150.1299mono_mass150.05282343smilesOC[C@H](O)[C@@H](O)C(=O)COformulaC5H10O5inchiInChI=1S/C5H10O5/c6-1-3(8)5(10)4(9)2-7/h3,5-8,10H,1-2H2/t3-,5+/m0/s1inchikeyZAQJHHRNXZUBTE-WVZVXSGGSA-Npolar_surface_area97.99refractivity31.6polarizability13.5rotatable_bond_count4acceptor_count5donor_count4physiological_charge0formal_charge0Ascorbate and aldarate metabolismec00053Pentose and glucuronate interconversionsec00040L-lyxose DegradationL-lyxose is an uncommon sugar in nature, and wild-type E. coli can not utilize it as a sole source of carbon and energy. However, mutations can arise that allow E. coli to metabolize L-lyxose through the use of enzymes of the rhamnose, arabinose and 2,3-diketo-L-gulonate systems.
L-lyxose enters the cell through the rhaT-encoded rhamnose transporter. It is then isomerized to L-xylulose by L-rhamnose isomerase.
Two types of mutations then allow further utilization of L-xylulose. Not shown here, a mutated from of L-rhamnulose kinase can phosphorylate L-xylulose, yielding L-xylulose-1-phosphate. Further metabolism to dihydroxyacetone phosphate and glycolate occurs through the rhamnulose-1-phosphate aldolase and aldehyde dehydrogenase A, NAD-linked enzymes. These products can enter glycolate degradation and glycolysis.
As shown here, L-xylulose can be phosphorylated by L-xylulose kinase in a mutant in which YiaJ, the repressor for the yiaKLMNO-lyxK-sgbHUE operon, has been disrupted. L-xylulose-5-phosphate is then further metabolized by predicted L-xylulose 5-phosphate 3-epimerase (so far only a predicted function) and either of two L-ribulose 5-phosphate 4-epimerases (SgbE or AraD) to D-xylulose-5-phosphate, which then enters the pentose phosphate pathway (non-oxidative branch).
The enzymes of L-rhamnose degradation I and L-arabinose degradation I are inducible by L-lyxose as well. (EcoCyc)PW002100MetabolicXylose Degradation ID-xylose, which can serve as a total source of carbon and energy for Escherichia coli K-12 substr. MG1655, enters the cell either through a low-affinity, proton-motive force-driven or a high-affinity, ATP-driven (ABC) transport system, so it is not phosphorylated during entry. Once inside the cell, an isomerase converts it to D-xylulose and subsequently a kinase converts it to D-xylulose 5-phosphate, an intermediate of the pentose phosphate pathway. Hence it flows through the pathways of central metabolism to satisfy the cell's need for precursor metabolites, reducing power, and metabolic energy. (EcoCyc)PW002105MetabolicSpecdb::CMs13703Specdb::CMs37743Specdb::NmrOneD306351Specdb::NmrOneD306352Specdb::NmrOneD306353Specdb::NmrOneD306354Specdb::NmrOneD306355Specdb::NmrOneD306356Specdb::NmrOneD306357Specdb::NmrOneD306358Specdb::NmrOneD306359Specdb::NmrOneD306360Specdb::NmrOneD306361Specdb::NmrOneD306362Specdb::NmrOneD306363Specdb::NmrOneD306364Specdb::NmrOneD306365Specdb::NmrOneD306366Specdb::NmrOneD306367Specdb::NmrOneD306368Specdb::NmrOneD306369Specdb::NmrOneD306370Specdb::MsMs29201Specdb::MsMs29202Specdb::MsMs29203Specdb::MsMs35759Specdb::MsMs35760Specdb::MsMs35761HMDB0075143920520892C0031217399Kanehisa, M., Goto, S., Sato, Y., Furumichi, M., Tanabe, M. (2012). "KEGG for integration and interpretation of large-scale molecular data sets." Nucleic Acids Res 40:D109-D114.22080510Winder, C. L., Dunn, W. B., Schuler, S., Broadhurst, D., Jarvis, R., Stephens, G. M., Goodacre, R. (2008). "Global metabolic profiling of Escherichia coli cultures: an evaluation of methods for quenching and extraction of intracellular metabolites." Anal Chem 80:2939-2948.18331064Oka H, Suzuki S, Suzuki H, Oda T: Increased urinary excretion of L-xylulose in patients with liver cirrhosis. Clin Chim Acta. 1976 Mar 1;67(2):131-6.1248150Ashwell, Gilbert; Kanfer, Julian; Burns, J. J. Mechanism of L-xylulose formation by kidney enzymes. Journal of Biological Chemistry (1959), 234 472-5.Xylose isomeraseP00944XYLA_ECOLIxylAhttp://ecmdb.ca/proteins/P00944.xmlRibulokinaseP08204ARAB_ECOLIaraBhttp://ecmdb.ca/proteins/P08204.xmlXylulose kinaseP09099XYLB_ECOLIxylBhttp://ecmdb.ca/proteins/P09099.xmlL-rhamnose isomeraseP32170RHAA_ECOLIrhaAhttp://ecmdb.ca/proteins/P32170.xmlRhamnulokinaseP32171RHAB_ECOLIrhaBhttp://ecmdb.ca/proteins/P32171.xmlL-xylulose/3-keto-L-gulonate kinaseP37677LYXK_ECOLIlyxhttp://ecmdb.ca/proteins/P37677.xml2,3-diketo-L-gulonate TRAP transporter small permease protein yiaMP37674YIAM_ECOLIyiaMhttp://ecmdb.ca/proteins/P37674.xml2,3-diketo-L-gulonate TRAP transporter large permease protein yiaNP37675YIAN_ECOLIyiaNhttp://ecmdb.ca/proteins/P37675.xml2,3-diketo-L-gulonate-binding periplasmic protein yiaOP37676YIAO_ECOLIyiaOhttp://ecmdb.ca/proteins/P37676.xmlOuter membrane protein NP77747OMPN_ECOLIompNhttp://ecmdb.ca/proteins/P77747.xmlOuter membrane pore protein EP02932PHOE_ECOLIphoEhttp://ecmdb.ca/proteins/P02932.xmlOuter membrane protein FP02931OMPF_ECOLIompFhttp://ecmdb.ca/proteins/P02931.xmlOuter membrane protein CP06996OMPC_ECOLIompChttp://ecmdb.ca/proteins/P06996.xmlAdenosine triphosphate + L-Threo-2-pentulose <> ADP + Hydrogen ion + L-Xylulose 5-phosphateR01901L-Lyxose > L-Threo-2-pentuloseAdenosine triphosphate + L-Threo-2-pentulose <> ADP + L-Xylulose 5-phosphateR01901Adenosine triphosphate + L-Threo-2-pentulose <> ADP + L-Xylulose 1-phosphateR01902Adenosine triphosphate + L-Threo-2-pentulose > ADP + L-Xylulose 5-phosphateL-Threo-2-pentulose + Adenosine triphosphate + L-Threo-2-pentulose > Xylulose 5-phosphate + Adenosine diphosphate + Xylulose 5-phosphate + ADPPW_R003849β-D-xylopyranose <> L-Threo-2-pentulosePW_R006134L-Threo-2-pentulose + Adenosine triphosphate > Xylulose 5-phosphate + ADP + Hydrogen ionPW_R006135L-Threo-2-pentulose + Adenosine triphosphate > L-Xylulose 5-phosphate + ADP + Hydrogen ionPW_R006125β-L-lyxopyranose <> L-Threo-2-pentulosePW_R006124