Trehalose: properties, sources, biosynthesis, role, and digestion

Trehalose is a disaccharide made up of two alpha-D-glucose molecules joined by an α-(1→1) glycosidic bond.[20]
It was discovered in an ergot fungus, genus Claviceps, by Wiggers H.A.L. in 1832.[28] Twenty-seven years after Wiggers’ work, in 1859, Berthelot M. isolated the disaccharide from Trehala manna, a cocoon-shaped substance produced by larval activity of weevils of Curculionidae family on some Echinops species, hence the name.[6]
Trehalose is a non-reducing sugar, and has a low chemical reactivity.[27] In nature, sucrose is the other widely distributed non-reducing sugar.[21]
It is present in all major groups of organisms such as bacteria, fungi, yeasts, algae, plants, and invertebrates, but it is absent in vertebrates.[2]
Dietary sources include some species of fungi, yeasts, crustaceans, honey, and processed foods to which it can be added as an additive.[10]
It can perform many functions, such as carbohydrate storage, energy source, component of membrane lipids, signaling molecule between plants and symbiont or pathogenic microorganisms, and protection against abiotic stress. In its phosphorylated form, is involved in the regulation of carbohydrate metabolism in plants.[17] Mammals are able to use exogenous trehalose as a source of carbon and energy.
Its intestinal digestion involves the enzyme trehalase (EC 3.2.1.28), which catalyzes a reaction leading to the release of the two glucose molecules that compose it.

Contents

Chemical properties

As with lactose, sucrose, and maltose, three other disaccharides, its molecular formula is C12H22O11 and its molecular weight is 342.30 g/mol.[20]
According to IUPAC nomenclature, its systematic name is alpha-D-gluco-hexopyranosyl alpha-D-gluco-hexopyranoside.
Since the α-(1→1) glycosidic bond occurs between the aldehyde function of two glucose units, that is, their anomeric carbons, in solution, it cannot exist in an open chain form with a free aldehyde group, that would act as a reducing agent. Hence, trehalose is a non-reducing sugar, and has a low chemical reactivity.[27]
At room temperature, it appears as white, orthorhombic crystals.
Its melting point is 203 °C (397.4 °F; 476.15 K).[20]
It has about 45 percent the sweetness of sucrose.[16]
Trehalose provides approximately 4 kcal/g of energy.

Dietary sources

Dietary sources are some species of fungi (Amanita spp.), especially if young, yeasts, crustaceans, and honey.[10] In 2000, the FDA authorized its use, classifying it as a food additives and including it, for example, in flavor enhancers and preservatives.[20] As it occurs in small amounts in a few unprocessed foods, processed foods such as frozen shrimp, fish in pouches, cereals and baked goods have become its major source.

Biosynthesis

Five pathways of biosynthesis have been identified in prokaryotes, of which only one, probably the most common, is also present in eukaryotes and is described below.[4]
It consists of two steps. In the first step, catalyzed by trehalose 6-phosphate synthase (EC 2.4.1.15), the condensation of UDP-glucose and glucose 6-phosphate leads to the formation of trehalose 6-phosphate. Trehalose 6-phosphate is then dephosphorylated to trehalose in the hydrolysis reaction catalyzed by trehalose 6-phosphate phosphatase (EC 3.1.3.12).

Biosynthesis of trehalose in eukaryotes, and hydrolysis by trehalase.
Biosynthesis and Hydrolysis of Trehalose

Its biosynthesis is strongly induced following exposure to abiotic stresses. The importance of this disaccharide is highlighted by the fact that some organisms possess more than one metabolic pathway for its biosynthesis.[24]
No gene involved in trehalose biosynthesis or storage is present in vertebrates. It does not seem that vertebrates lost the ability to produce the disaccharide during the evolutionary process; rather, they appear never to have acquired such capacity.[2]

Trehalose in plants

It is the major disaccharide present in growing plants.[18]
It was first detected in plants in 1913 in Selaginella lepidophylla, also known as resurrection fern or false rose of Jericho, a desiccation-tolerant vascular plant.[1] It was subsequently also found in green algae, mosses, and liverworts, non-vascular plants of the Marchantiophyta division, and ferns.[10] Its presence in angiosperms was long believed to be due to microbial or bacterial contamination, or to an analytical artifact. Things began to change when, from the 1990s, large amounts of the disaccharide were found in desiccation-tolerant angiosperms, such as Myrothamnus flabellifolius and Sporobolus spp., amounts that could not be ascribed to microbial contamination.[9][15]
Despite this, trehalose and its metabolism were considered unimportant or even absent in most angiosperms until two observations led to a paradigm shift. In 1998, in Arabidopsis thaliana, a desiccation-intolerant plant belonging to the Brassicaceae family, which is used as a model for higher plants, genes were identified that encode catalytically active trehalose 6-phosphate synthase and trehalose 6-phosphate phosphatase.[7][25] Furthermore, again in angiosperms, the importance of trehalose metabolism has also arisen from attempts to engineer its production with the introduction of fungal or bacterial enzymes: transgenic plants were obtained with a broad spectrum of phenotypic anomalies, such as delayed senescence and altered leaf shapes. These observations therefore suggested that in angiosperms:

  • the capacity to synthesize trehalose is not limited to resurrection plants;
  • a disturbance of its metabolism has far-reaching effects on metabolism and development.

Currently, genes encoding trehalose 6-phosphate synthase and trehalose 6-phosphate phosphatase have been identified in all major plant taxa, suggesting that the capacity to synthesize the disaccharide is universal in the plant kingdom.[13]

Role

Trehalose performs multiple functions in very different organisms. Some functions are shared by different organisms, whereas others are peculiar to specific organisms.

  • In plants, insects, nematodes and bacteria, it is involved in the adaptive response to abiotic stresses, such as extreme temperatures, changes in osmotic pressure and salinity, nutrient deprivation, or desiccation caused by salt or drought.[17] By accumulating in the cell, it helps to overcome stressful conditions by limiting damage to biological molecules.[18] In plants, trehalose accumulation under stress conditions is related to transcriptional activation of the genes encoding biosynthesis enzymes or to inhibition of trehalase activity.[12]
    Once stress condition are relieved, trehalose returns to normal levels.[17]
  • It can act as a storage carbohydrate and carbon transport molecule.
    In some bacterial spores, it is accumulated up to about 25 percent of the spore dry weight.[19]
    Some bacteria can use it as an exogenous carbon source.[2]
    It is stored in fungi and yeasts during dormancy.[5]
    It is the main sugar present in insect hemolymph, where it constitutes 80-90 percent of the carbohydrates, and is a rapidly available source of energy for flight.[10][29]
  • It is a potential signaling metabolite in the interactions between plants and symbiotic and pathogenic microorganisms, as well as herbivorous insects.[18] Moreover, some bacteria and fungi rely on its metabolism for infectivity.[17]

Other roles

It is a component of lipids found in cell walls of bacteria belonging to the genera Corynebacterium and Mycobacterium, where it plays a structural role.[11] For example, M. tuberculosis cell wall contains glycolipids derived from trehalose, such as sulfolipids, and diacyl-, triacyl-, and polyacyltrealoses, where fatty acids are linked to the hydroxyl groups of trehalose and not of glycerol.[24]
It is believed to protect unsaturated fatty acids with cis double bonds from oxidative damage. It has also been proposed that it is able to prevent protein aggregation by interacting with cis double bonds present in the side chains of aromatic amino acids and by limiting the acetylation of the ε-amino group of side chain of lysine residues, which would increase protein hydrophobicity.[24]
It plays a key role in the growth and development of insects, accounting for about 20 percent of the total carbohydrate pool in certain stages of their development.[2]
Trehalose 6-phosphate is essential for the embryonic and vegetative development of plants, as well as for the metabolism of sucrose and starch.[23] It has been hypothesized that the main role of trehalose 6-phosphate is to signal and regulate sucrose levels, acting as a negative feedback regulator.[26]

Molecular mechanisms of protective potential

Trehalose is involved in the response to abiotic stresses in different organisms.[17]
It is believed that its protective potential is due to several mechanisms that act together, and are a consequence of its chemical properties, in particular that of being a non-reducing sugar.[27]
Due to its low chemical reactivity, it does not readily interact with other molecules present in the cell, such as proteins, DNA or RNA.[8]
Its high hydrophilicity allows it to form strong hydrogen bonds with water, which are stronger than the water-water bonds. Moreover, although other disaccharides can displace water, trehalose has a greater hydration number compared to other disaccharides. Its low chemical reactivity and high hydrophilicity allow it to be compatible with cellular metabolism even at high concentrations.[18]
The flexibility of the α-(1→1) glycosidic bond, greater than the flexibility of glycosidic bond of other disaccharides, allows trehalose to esily conform to the polar groups of the molecules.[8]
The strong resistance of the α-(1→1) glycosidic bond to cleavage by glucosidases and acid hydrolysis is also important.[24]
However, the key difference that sets trehalose apart from other disaccharides is its ability to form a sort of glassy structure around molecules. This structure would be stable even at high temperatures and during desiccation. What appears to be occurring is that trehalose, displacing water molecules normally linked by hydrogen bonds with biological molecules, such as proteins, would keep them properly folded in their native structure.[16]

Trehalose digestion

In mammals, most carbohydrate digestion takes place in the duodenum. Pancreatic alpha-amylase and hydrolases of the brush border of enterocytes hydrolyze disaccharides, oligosaccharides, and polysaccharides into the constituent monosaccharides, that is, glucose, fructose, and galactose. This is followed by absorption of monosaccharides.[22]
The α-(1→1) glycosidic bond of trehalose is cleaved in the hydrolysis reaction catalyzed by trehalase. Two molecules of D-glucose are released for each hydrolytic cleavage.

Trehalase deficiency

There are two genes in the human genome that encode trehalase isoforms.[2] Mutations in the genes coding for trehalase lead to the biosynthesis of mutant proteins with little or no function. As a result, undigested trehalose can cause osmotic diarrhea and, once in the colon, interact with bacteria of the gut microbiota, which is part of the larger human microbiota. Bacteria produce excessive amounts of gas, short-chain fatty acids, mainly acetic acid, propionic acid and butyric acid, and alcohol, which cause the other signs and symptoms of trehalose intolerance such as osmotic-fermentative diarrhea, malabsorption, and other abdominal symptoms.[14]
Since there is no cure for trehalase deficiency currently, the only treatment is to avoid or reduce the consumption of foods contain trehalose.[3]
Trehalase deficiency is quite rare, although it is more frequent in Greenland, affecting about eight percent of the population.

References

  1. ^ Anselmino O. and Gilg E. Uber das Vorkommen von Trehalose in Selaginella lepidophylla. Ber Deut Pharm Ges 1913;23:326-330
  2. ^ a b c d e Argüelles J.C. Why can’t vertebrates synthesize trehalose? J Mol Evol 2014;79:111-116. doi:10.1007/s00239-014-9645-9
  3. ^ Arola H., Koivula T., Karvonen A.L., Jokela H., Ahola T., Isokoski M. Low trehalase activity is associated with abdominal symptoms caused by edible mushrooms. Scand J Gastroenterol 1999;34(9):898-903. doi:10.1080/003655299750025372
  4. ^ Avonce N., Mendoza-Vargas A., Morett E., Iturriaga G. Insights on the evolution of trehalose biosynthesis. BMC Evol Biol 2006;6:109. doi:10.1186/1471-2148-6-109
  5. ^ Barton J.K., Den Hollander J.A., Hopfield J.J., Shulman R.G. 13C nuclear magnetic resonance study of trehalose mobilization in yeast spores. J Bacteriol 1982;151(1):177-85. doi:10.1128/jb.151.1.177-185.1982
  6. ^ Berthelot M. Nouvelles recherches sur les corps analogues au sucre de canne. Annales de Chimie et de Physique 1859 3a serie;55:269-282
  7. ^ Blazquez M., Santos E., Flores C., Martinez-Zapater J., Salinas J., Gancedo C. Isolation and molecular characterization of the Arabidopsis TPS1 gene, encoding trehalose-6-phosphate synthase. Plant J 1998;13(5):685-9. doi:10.1046/j.1365-313x.1998.00063.x
  8. ^ a b Colaco C., Kampinga J., Roser B. Amorphous stability and trehalose. Science. 1995;268(5212):788. doi:10.1126/science.7754360
  9. ^ Drennan P.M., Smith M.T., Goldsworthy D., Van Staden J. The occurrence of trehalose in the leaves of the desiccation-tolerant angiosperm Myrothamnus flabellifolius Welw. J Plant Physiol 1993;142(4):493-6. doi:10.1016/S0176-1617(11)81257-5
  10. ^ a b c d Elbein A.D. The metabolism of alpha,alpha-trehalose. Adv Carbohydr Chem Biochem 1974;30:227-56. doi:10.1016/s0065-2318(08)60266-8
  11. ^ Elbein A.D., Pan Y.T., Pastuszak I., Carroll D. New insights on trehalose: a multifunctional molecule. Glycobiology 2003;13(4):17R-27R. doi:10.1093/glycob/cwg047
  12. ^ Fernandez O., Béthencourt L., Quero A., Sangwan R.S., Clément C. Trehalose and plant stress responses: friend or foe? Trends Plant Sci 2010;15(7):409-17. doi:10.1016/j.tplants.2010.04.004
  13. ^ Figueroa C.M., Lunn J.E. A tale of two sugars: trehalose 6-phosphate and sucrose. Plant Physiol 2016;172(1):7-27. doi:10.1104/pp.16.00417
  14. ^ Holtug K., Clausen M.R., Hove H., Christiansen J., Mortensen P.B. The colon in carbohydrate malabsorption: short-chain fatty acids, pH, and osmotic diarrhoea. Scand J Gastroenterol 1992;27(7):545-52. doi:10.3109/00365529209000118
  15. ^ Iturriaga G., Gaff D.F., Zentella R. New desiccation-tolerant plants, including a grass, in the central highlands of Mexico, accumulate trehalose. Australian Journal of Botany 2000;48(2):153-8. doi:10.1071/BT98062
  16. ^ a b Jain N.K., Roy I. Effect of trehalose on protein structure. Protein Sci 2009;18(1):24-36. doi:10.1002/pro.3
  17. ^ a b c d e Lee H.J., Yoon Y.S., Lee S.J. Mechanism of neuroprotection by trehalose: controversy surrounding autophagy induction. Cell Death Dis 2018;9(7):712. doi:10.1038/s41419-018-0749-9
  18. ^ a b c d Lunn J.E., Delorge I., Figueroa C.M., Van Dijck P., Stitt M. Trehalose metabolism in plants. Plant J 2014;79(4):544-67. doi:10.1111/tpj.12509
  19. ^ McBride M.J., Ensign J.C. Effects of intracellular trehalose content on Streptomyces griseus spores. J Bacteriol 1987;169(11):4995-5001. doi:10.1128/jb.169.11.4995-5001.1987
  20. ^ a b c d e National Center for Biotechnology Information. PubChem Compound Summary for CID 7427, Trehalose. https://pubchem.ncbi.nlm.nih.gov/compound/Trehalose. Accessed Dec. 31, 2023
  21. ^ Nelson D.L., Cox M.M. Lehninger. Principles of biochemistry. 6th Edition. W.H. Freeman and Company, 2012
  22. ^ Rosenthal M.D., Glew R.H. Medical biochemistry: human metabolism in health and disease. A John Wiley & sons, Inc., Publication, 2009
  23. ^ Schluepmann H., Pellny T., van Dijken A., Smeekens S. and Paul M. Trehalose 6-phosphate is indispensable for carbohydrate utilization and growth in Arabidopsis thaliana. Proc Natl Acad Sci 2003;100(11):6849-6854. doi:10.1073/pnas.1132018100
  24. ^ a b c d Vanaporn M., Titball R.W. Trehalose and bacterial virulence. Virulence 2020 Dec;11(1):1192-1202. doi:10.1080/21505594.2020.1809326
  25. ^ Vogel G., Aeschbacher R.A., Muller J., Boller T., Wiemken A. Trehalose-6-phosphate phosphatases from Arabidopsis thaliana: identification by functional complementation of the yeast tps2 mutant. Plant J 1998;13:673-683. doi:10.1046/j.1365-313X.1998.00064.x
  26. ^ Yadav U.P., Ivakov A., Feil R., Duan G.Y., Walther D., Giavalisco P., Piques M., Carillo P., Hubberten H.M., Stitt M., Lunn J.E. The sucrose-trehalose 6-phosphate (Tre6P) nexus: specificity and mechanisms of sucrose signalling by Tre6P. J Exp Bot 2014;65(4):1051-68. doi:10.1093/jxb/ert457
  27. ^ a b Yoon Y.S., Cho E.D., Jung Ahn W., Won Lee K., Lee S.J., Lee H.J. Is trehalose an autophagic inducer? Unraveling the roles of non-reducing disaccharides on autophagic flux and alpha-synuclein aggregation. Cell Death Dis 20175;8(10):e3091. doi:10.1038/cddis.2017.501
  28. ^ Wiggers H.A.L. Untersuchung über das Mutterkorn, Secale cornutum. Annalen der Pharmacie 1832;1(2):129-182. doi:10.1002/jlac.18320010202
  29. ^ Wyatt G.R., Kale G.F. The chemistry of insect hemolymph. II. Trehalose and other carbohydrates. J Gen Physiol 1957;40(6):833-47. doi:10.1085/jgp.40.6.833

Biochemistry and metabolism