Heptose

Last updated

A heptose is a monosaccharide with seven carbon atoms.

Contents

They have either an aldehyde functional group in position 1 (aldoheptoses) or a ketone functional group in position 2, 3 or 4 (ketoheptoses). Ketoheptoses have 4 chiral centers, whereas aldoheptoses have 5.

Examples

There are few examples of seven-carbon sugars in nature, among which are:

Structural role

The production of heptose is conserved across gram-negative bacteria. In the form of L-glycero-D-mannose-heptose, heptose is a key component in the secondary membrane of gram-negative bacteria. Gram-negative bacteria, in addition to having a cell wall, are also encapsulated by a membrane composed of lipopolysaccharides. [5] These lipopolysaccharides comprise an endotoxin that acts as an immune system agonist and elicits strong responses. This toxin, known as lipid A, consists of a core of one to three heptose molecules. [5] The 7-carbon heptose molecules are essential for stability in the lipopolysaccharide membrane, forming an interconnected network utilizing divalent cations. [5]

Role in cell signaling

Heptose, in the form of heptose 1-7-bisphosphate, has been found to be one of the components responsible for the pathogenic nature of gram negative bacteria. In the bacterium biosynthesis pathway, heptose is phosphorylated to heptose 1-7-bisphosphate. In addition, like other sugars, heptose may exist in either the alpha anomer or the beta anomer. Before synthetic production of heptose-bisphosphate (HBP) for studies, cytosolic HBP was thought to influence NF-kB, a transcription factor in mammalian cells. [5] [6] Along with producing the first synthetic version of HBP, it was shown that the beta form of the heptose acts as a pathogen-associated molecular pattern (PAMP) and activates the NF-kB signaling pathway. [6] A PAMP is a specific structure, component, or molecule that triggers the immune response after recognition by pattern recognition receptors on mammalian cells. [5]

Related Research Articles

<span class="mw-page-title-main">Lipid</span> Substance of biological origin that is soluble in nonpolar solvents

Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries, and in nanotechnology.

<span class="mw-page-title-main">Triose</span> Sugar containing three carbon atoms

A triose is a monosaccharide, or simple sugar, containing three carbon atoms. There are only three possible trioses: the two enantiomers of glyceraldehyde, which are aldoses; and dihydroxyacetone, a ketose which is symmetrical and therefore has no enantiomers.

<span class="mw-page-title-main">Teichoic acid</span> Copolymers found in some bacteria

Teichoic acids are bacterial copolymers of glycerol phosphate or ribitol phosphate and carbohydrates linked via phosphodiester bonds.

<span class="mw-page-title-main">Lipopolysaccharide</span> Class of molecules found in the outer membrane of gram-negative bacteria

Lipopolysaccharide, now more commonly known as endotoxin, is a collective term for components of the outermost membrane of cell envelope of gram-negative bacteria, such as E. coli and Salmonella with a common structural architecture. Lipopolysaccharides (LPS) are large molecules consisting of three parts: an outer core polysaccharide termed the O-antigen, an inner core oligosaccharide and Lipid A, all covalently linked. In current terminology, the term endotoxin is often used synonymously with LPS, although there are a few endotoxins that are not related to LPS, such as the so-called delta endotoxin proteins produced by Bacillus thuringiensis.

<span class="mw-page-title-main">Ketose</span> Monosaccharides with one >C=O group per molecule

In organic chemistry, a ketose is a monosaccharide containing one ketone group per molecule. The simplest ketose is dihydroxyacetone, which has only three carbon atoms. It is the only ketose with no optical activity. All monosaccharide ketoses are reducing sugars, because they can tautomerize into aldoses via an enediol intermediate, and the resulting aldehyde group can be oxidised, for example in the Tollens' test or Benedict's test. Ketoses that are bound into glycosides, for example in the case of the fructose moiety of sucrose, are nonreducing sugars.

<span class="mw-page-title-main">Calvin cycle</span> Light-independent reactions in photosynthesis

The Calvin cycle, light-independent reactions, bio synthetic phase, dark reactions, or photosynthetic carbon reduction (PCR) cycle of photosynthesis is a series of chemical reactions that convert carbon dioxide and hydrogen-carrier compounds into glucose. The Calvin cycle is present in all photosynthetic eukaryotes and also many photosynthetic bacteria. In plants, these reactions occur in the stroma, the fluid-filled region of a chloroplast outside the thylakoid membranes. These reactions take the products of light-dependent reactions and perform further chemical processes on them. The Calvin cycle uses the chemical energy of ATP and reducing power of NADPH from the light dependent reactions to produce sugars for the plant to use. These substrates are used in a series of reduction-oxidation (redox) reactions to produce sugars in a step-wise process; there is no direct reaction that converts several molecules of CO2 to a sugar. There are three phases to the light-independent reactions, collectively called the Calvin cycle: carboxylation, reduction reactions, and ribulose 1,5-bisphosphate (RuBP) regeneration.

<span class="mw-page-title-main">Phosphatidylinositol</span> Signaling molecule

Phosphatidylinositol or inositol phospholipid is a biomolecule. It was initially called "inosite" when it was discovered by Léon Maquenne and Johann Joseph von Scherer in the late 19th century. It was discovered in bacteria but later also found in eukaryotes, and was found to be a signaling molecule.

<span class="mw-page-title-main">Lipid A</span>

Lipid A is a lipid component of an endotoxin held responsible for the toxicity of gram-negative bacteria. It is the innermost of the three regions of the lipopolysaccharide (LPS), also called endotoxin molecule, and its hydrophobic nature allows it to anchor the LPS to the outer membrane. While its toxic effects can be damaging, the sensing of lipid A by the immune system may also be critical for the onset of immune responses to gram-negative infection, and for the subsequent successful fight against the infection.

<span class="mw-page-title-main">Glycerophospholipid</span> Class of lipids

Glycerophospholipids or phosphoglycerides are glycerol-based phospholipids. They are the main component of biological membranes in eukaryotic cells. They are a type of lipid, of which its composition affects membrane structure and properties. Two major classes are known: those for bacteria and eukaryotes and a separate family for archaea.

Pathogen-associated molecular patterns (PAMPs) are small molecular motifs conserved within a class of microbes, but not present in the host. They are recognized by toll-like receptors (TLRs) and other pattern recognition receptors (PRRs) in both plants and animals. This allows the innate immune system to recognize pathogens and thus, protect the host from infection.

<span class="mw-page-title-main">Fructose-bisphosphate aldolase</span>

Fructose-bisphosphate aldolase, often just aldolase, is an enzyme catalyzing a reversible reaction that splits the aldol, fructose 1,6-bisphosphate, into the triose phosphates dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (G3P). Aldolase can also produce DHAP from other (3S,4R)-ketose 1-phosphates such as fructose 1-phosphate and sedoheptulose 1,7-bisphosphate. Gluconeogenesis and the Calvin cycle, which are anabolic pathways, use the reverse reaction. Glycolysis, a catabolic pathway, uses the forward reaction. Aldolase is divided into two classes by mechanism.

<span class="mw-page-title-main">Saccharolipid</span> Class of chemical compounds

Saccharolipids are chemical compounds containing fatty acids linked directly to a sugar backbone, forming structures that are compatible with membrane bilayers. In the saccharolipids, a monosaccharide substitutes for the glycerol backbone present in glycerolipids and glycerophospholipids. The most familiar saccharolipids are the acylated glucosamine precursors of the lipid A component of the lipopolysaccharides in Gram-negative bacteria. Typical lipid A molecules are disaccharides of glucosamine, which are derivatized with as many as seven fatty-acyl chains. The minimal lipopolysaccharide required for growth in Escherichia coli is Kdo2-Lipid A, a hexa-acylated disaccharide of glucosamine (LipidA) that is glycosylated with two 3-deoxy-D-manno-octulosonic acid (Kdo) residues.

Core oligosaccharide is a short chain of sugar residues within Gram-negative lipopolysaccharide (LPS). Core-OS are highly diverse among bacterial species and even within strains of species

D-glycero-beta-D-manno-heptose-7-phosphate kinase is an enzyme with systematic name ATP:D-glycero-beta-D-manno-heptose 7-phosphate 1-phosphotransferase. This enzyme catalyses the following chemical reaction

D-glycero-alpha-D-manno-heptose-7-phosphate kinase is an enzyme with systematic name ATP:D-glycero-alpha-D-manno-heptose 7-phosphate 1-phosphotransferase. This enzyme catalyses the following chemical reaction

D-glycero-beta-D-manno-heptose 1-phosphate adenylyltransferase is an enzyme with systematic name ATP:D-glycero-beta-D-manno-heptose 1-phosphate adenylyltransferase. This enzyme catalyses the following chemical reaction

D-glycero-alpha-D-manno-heptose 1-phosphate guanylyltransferase is an enzyme with systematic name GTP:D-glycero-alpha-D-manno-heptose 1-phosphate guanylyltransferase. This enzyme catalyses the following chemical reaction

D-glycero-β-D-manno-heptose 1,7-bisphosphate 7-phosphatase (EC 3.1.3.82) is an enzyme with systematic name D-glycero-β-D-manno-heptose 1,7-bisphosphate 7-phosphohydrolase. This enzyme catalyses the following chemical reaction

D-glycero-α-D-manno-heptose 1,7-bisphosphate 7-phosphatase (EC 3.1.3.83) is an enzyme with systematic name D-glycero-α-D-manno-heptose 1,7-bisphosphate 7-phosphohydrolase. This enzyme catalyses the following chemical reaction

D-sedoheptulose 7-phosphate isomerase is an enzyme with systematic name D-glycero-D-manno-heptose 7-phosphate aldose-ketose-isomerase. This enzyme catalyses the following chemical reaction

References

  1. ↑ Horecker, B. L; Smyrniotis, P. Z (1953). "Transaldolase: The Formation of Fructose-6-Phosphate from Sedoheptulose-7-Phosphate". Journal of the American Chemical Society. 75 (8): 2021. Bibcode:1953JAChS..75.2021H. doi:10.1021/ja01104a532.
  2. ↑ Patra, Krushna C; Hay, Nissim (2014). "The pentose phosphate pathway and cancer". Trends in Biochemical Sciences. 39 (8): 347–354. doi:10.1016/j.tibs.2014.06.005. PMC   4329227 . PMID   25037503.
  3. ↑ Liu, Xuan; Sievert, James; Arpaia, Mary Lu; Madore, Monica A. (2002-01-01). "Postulated Physiological Roles of the Seven-carbon Sugars, Mannoheptulose, and Perseitol in Avocado". Journal of the American Society for Horticultural Science. 127 (1): 108–114. doi: 10.21273/JASHS.127.1.108 . Retrieved 2018-06-26.
  4. ↑ Taylor, Patricia L.; Blakely, Kim M.; de Leon, Gladys P.; Walker, John R.; McArthur, Fiona; Evdokimova, Elena; Zhang, Kun; Valvano, Miguel A.; Wright, Gerard D.; Junop, Murray S. (1 February 2008). "Structure and Function of Sedoheptulose-7-phosphate Isomerase, a Critical Enzyme for Lipopolysaccharide Biosynthesis and a Target for Antibiotic Adjuvants". Journal of Biological Chemistry. 283 (5): 2835–2845. doi: 10.1074/jbc.M706163200 . PMID   18056714.
  5. 1 2 3 4 5 Gaudet, Ryan G.; Gray-Owen, Scott D. (2016-09-22). "Heptose Sounds the Alarm: Innate Sensing of a Bacterial Sugar Stimulates Immunity". PLOS Pathogens. 12 (9): e1005807. doi: 10.1371/journal.ppat.1005807 . ISSN   1553-7374. PMC   5033458 . PMID   27658039.
  6. 1 2 Inuki, Shinsuke; Aiba, Toshihiko; Kawakami, Shota; Akiyama, Taishin; Inoue, Jun-ichiro; Fujimoto, Yukari (2017-06-16). "Chemical Synthesis of d - glycero - d - manno -Heptose 1,7-Bisphosphate and Evaluation of Its Ability to Modulate NF-κB Activation". Organic Letters. 19 (12): 3079–3082. doi:10.1021/acs.orglett.7b01158. ISSN   1523-7060. PMID   28541700.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.