Heptose
A heptose is a monosaccharide with seven carbon atoms.
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
[edit]There are few examples of seven-carbon sugars in nature, among which are:
- sedoheptulose or D-altro-heptulose (a ketose), an intermediate in the Calvin cycle and in lipid A biosynthesis[1][2]
- mannoheptulose (a ketose), found in avocadoes[3]
- L-glycero-D-manno-heptose (an aldose), a late intermediate in lipid A biosynthesis.[4]
Structural role
[edit]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
[edit]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]
References
[edit]- ^ 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.
- ^ 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 25037503.347-354&rft.date=2014&rft_id=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4329227#id-name=PMC&rft_id=info:pmid/25037503&rft_id=info:doi/10.1016/j.tibs.2014.06.005&rft.aulast=Patra&rft.aufirst=Krushna+C&rft.au=Hay,+Nissim&rft_id=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4329227&rfr_id=info:sid/en.wikipedia.org:Heptose" class="Z3988">
- ^ 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 2018-06-26.108-114&rft.date=2002-01-01&rft_id=info:doi/10.21273/JASHS.127.1.108&rft.aulast=Liu&rft.aufirst=Xuan&rft.au=Sievert,+James&rft.au=Arpaia,+Mary+Lu&rft.au=Madore,+Monica+A.&rft_id=http://journal.ashspublications.org/content/127/1/108.abstract&rfr_id=info:sid/en.wikipedia.org:Heptose" class="Z3988">
- ^ 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 18056714.2835-2845&rft.date=2008-02-01&rft_id=info:doi/10.1074/jbc.M706163200&rft_id=info:pmid/18056714&rft.aulast=Taylor&rft.aufirst=Patricia+L.&rft.au=Blakely,+Kim+M.&rft.au=de+Leon,+Gladys+P.&rft.au=Walker,+John+R.&rft.au=McArthur,+Fiona&rft.au=Evdokimova,+Elena&rft.au=Zhang,+Kun&rft.au=Valvano,+Miguel+A.&rft.au=Wright,+Gerard+D.&rft.au=Junop,+Murray+S.&rft_id=https://doi.org/10.1074%2Fjbc.M706163200&rfr_id=info:sid/en.wikipedia.org:Heptose" class="Z3988">
- ^ a b c d e 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.
- ^ a b 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 28541700.3079-3082&rft.date=2017-06-16&rft.issn=1523-7060&rft_id=info:pmid/28541700&rft_id=info:doi/10.1021/acs.orglett.7b01158&rft.aulast=Inuki&rft.aufirst=Shinsuke&rft.au=Aiba,+Toshihiko&rft.au=Kawakami,+Shota&rft.au=Akiyama,+Taishin&rft.au=Inoue,+Jun-ichiro&rft.au=Fujimoto,+Yukari&rft_id=https://pubs.acs.org/doi/10.1021/acs.orglett.7b01158&rfr_id=info:sid/en.wikipedia.org:Heptose" class="Z3988">
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