Cellulose synthase (UDP-forming)

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Structure of a bacterial cellulose synthase.png
Structure of a bacterial cellulose synthase
Identifiers
EC number 2.4.1.12
CAS number 9027-19-4
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum

In enzymology, a cellulose synthase (EC 2.4.1.12, UDP-glucose:(1→4)-β-D-glucan 4-β-D-glucosyltransferase) is an enzyme that catalyzes the chemical reaction

UDP-glucose + [(1→4)-β-D-glucosyl]n = UDP + [(1→4)-β-D-glucosyl]n+1

Thus, the two substrates of this enzyme are UDP-glucose and [(1→4)-β-D-glucosyl]n, whereas its two products are UDP and [(1→4)-β-D-glucosyl]n+1.

This enzyme is involved in the synthesis of cellulose. A similar enzyme utilizes GDP-glucose, cellulose synthase (GDP-forming) (EC 2.4.1.29).

Cellulose[edit]

Cellulose is an aggregation of unbranched polymer chains made of β-(1→4)-linked glucose residues that makes up a large portion of primary and secondary cell walls.[1][2][3][4] Although important for plants, it is also synthesized by most algae, some bacteria, and some animals.[5][6][7][8] Worldwide, 2 × 1011 tons of cellulose microfibrils are produced,[9] which serves as a critical source of renewable biofuels and other biological-based products, such as lumber, fuel, fodder, paper and cotton.[2][10]

Purpose of cellulose[edit]

These microfibrils are made on the surface of cell membranes to reinforce cells walls, which has been researched extensively by plant biochemists and cell biologist because 1) they regulate cellular morphogenesis and 2) they serve alongside many other constituents (i.e. lignin, hemicellulose, pectin) in the cell wall as a strong structural support and cell shape.[10] Without these support structures, cell growth would cause a cell to swell and spread in all directions, thus losing its shape viability [11]

Cellulose synthase structure[edit]

Plant cellulose synthases belong to the family of glycosyltransferases, which are proteins involved in the biosynthesis and hydrolysis of the bulk of earth's biomass.[12] Cellulose is synthesized by large cellulose synthase complexes (CSCs), which consist of synthase protein isoforms (CesA) that are arranged into a unique hexagonal structure known as a “particle rosette” 50 nm wide and 30–35 nm tall.[6][13][14] There are more than 20 of these full-length integral membrane proteins, each of which is around 1000 amino acids long,[2][3] these rosettes, formerly known as granules, were first discovered in 1972 by electron microscopy in green algae species Cladophora and Chaetomorpha[15] (Robinson et al. 1972). Solution x-ray scattering have shown that CesAs are at the surface of a plant cell and are elongated monomers with a two catalytic domains that fuse together into dimers. The center of the dimers is the main point of catalytic activity,[6] since cellulose is made in all cell walls, CesA proteins are present in all tissues and cell types of plants. Nonetheless, there are different types of CesA, some tissue types may have varying concentrations of one over another, for example, the AtCesA1 (RSW1) protein is involved in the biosynthesis of primary cell walls throughout the whole plant while the AtCesA7 (IRX3) protein is only expressed in the stem for secondary cell wall production.[16]

Cellulose synthase activity[edit]

Cellulose biosynthesis is the process during which separate homogeneous β-(1→4)-glucan chains, ranging from 2,000 to 25,000 glucose residues in length, are synthesized and then immediately hydrogen bond with one another to form rigid crystalline arrays, or microfibrils.[2] Microfibrils in the primary cell wall are approximately 36 chains long while those of the secondary cell wall are much larger, containing up to 1200 β-(1→4)-glucan chains.[10][16] Uridine diphosphate-glucose (UDP), which is produced by the enzyme sucrose synthase (SuSy) that produces and transports UDP-glucose to the plasma membrane is the substrate used by cellulose synthase to produce the glucan chains,[2][17] the rate at which glucose residues are synthesized per one glucan chain ranges from 300 to 1000 glucose residues per minute, the higher rate being more prevalent in secondary wall particles, such as in the xylem.[18][19]

Supporting structures[edit]

Microfibril synthesis is guided by cortical microtubules, which lie beneath the plasma membrane of elongating cells, in that they form a platform on which the CSCs can convert glucose molecules into the crystalline chains, the microtubule–microfibril alignment hypothesis proposes that cortical microtubules, which lie beneath the plasma membrane of elongating cells, provide tracks for CSCs that convert glucose molecules into crystalline cellulose microfibrils.[20] The direct hypothesis postulates some types of direct linkage between CESA complexes and microtubules.[17] Additionally, the KORRIGAN (KOR1) protein is thought to be a critical component of cellulose synthesis in that it acts cellulose at the plasma membrane-cell wall interface. KOR1 interacts with a two specific CesA proteins, possibly by proof-reading and relieving stress created glucan chain synthesis by hydrolyzing disordered amorphous cellulose.[21]

Environmental influences[edit]

Cellulose synthesis activity is affected by many environmental stimuli, such as hormones, light, mechanical stimuli, nutrition, and interactions with the cytoskeleton. Interactions with these factors may influence cellulose deposition in that it affects the amount of substrate produced and the concentration and/or activity of CSCs in the plasma membrane.[2][6]

References[edit]

  1. ^ Campbell JA, Davies GJ, Bulone V, Henrissat B (September 1997). "A classification of nucleotide-diphospho-sugar glycosyltransferases based on amino acid sequence similarities". The Biochemical Journal. 326 ( Pt 3): 929–39. doi:10.1042/bj3260929u. PMC 1218753Freely accessible. PMID 9334165. 
  2. ^ a b c d e f Olek AT, Rayon C, Makowski L, Kim HR, Ciesielski P, Badger J, Paul LN, Ghosh S, Kihara D, Crowley M, Himmel ME, Bolin JT, Carpita NC (July 2014). "The structure of the catalytic domain of a plant cellulose synthase and its assembly into dimers". The Plant Cell. 26 (7): 2996–3009. doi:10.1105/tpc.114.126862. PMID 25012190. 
  3. ^ a b Richmond T (2000). "Higher plant cellulose synthases". Genome Biology. 1 (4): REVIEWS3001. doi:10.1186/gb-2000-1-4-reviews3001. PMID 11178255. 
  4. ^ Lei L, Li S, Gu Y (2012). "Cellulose synthase complexes: composition and regulation". Frontiers in Plant Science. 3: 75. doi:10.3389/fpls.2012.00075. PMID 22639663. 
  5. ^ Nakashima K, Yamada L, Satou Y, Azuma J, Satoh N (February 2004). "The evolutionary origin of animal cellulose synthase". Development Genes and Evolution. 214 (2): 81–8. doi:10.1007/s00427-003-0379-8. PMID 14740209. 
  6. ^ a b c d Yin Y, Huang J, Xu Y (July 2009). "The cellulose synthase superfamily in fully sequenced plants and algae". BMC Plant Biology. 9: 99. doi:10.1186/1471-2229-9-99. PMC 3091534Freely accessible. PMID 19646250. 
  7. ^ Sethaphong L, Haigler CH, Kubicki JD, Zimmer J, Bonetta D, DeBolt S, Yingling YG (April 2013). "Tertiary model of a plant cellulose synthase". Proceedings of the National Academy of Sciences of the United States of America. 110 (18): 7512–7. doi:10.1073/pnas.1301027110. PMC 3645513Freely accessible. PMID 23592721. 
  8. ^ Li, Lei, Gu, S, L, Y (2012). "Functional analysis of complexes with mixed primary and secondary cellulose synthases". Plant Signaling and Behavior. 8: 23179. 
  9. ^ Lieth, H (1975). Measurement of calorific values. Primary productivity of the biosphere. New York: Springer. pp. 119–129. 
  10. ^ a b c Cutler S, Somerville C (February 1997). "Cloning in silico". Current Biology. 7 (2): R108–11. doi:10.1016/S0960-9822(06)00050-9. PMID 9081659. 
  11. ^ Hogetsu T, Shibaoka H (January 1978). "Effects of colchicine on cell shape and on microfibril arrangement in the cell wall of Closterium acerosum". Planta. 140 (1): 15–8. doi:10.1007/BF00389374. PMID 24414355. 
  12. ^ Campbell JA, Davies GJ, Bulone V, Henrissat B (February 1998). "A classification of nucleotide-diphospho-sugar glycosyltransferases based on amino acid sequence similarities". The Biochemical Journal. 329 (Pt 3): 719. PMC 1219098Freely accessible. PMID 9445404. 
  13. ^ Giddings, Brower, Staehelin, TH, DL, LA (1980). "formation of cellulose fibrils in primary and secondary walls". Journal of Cellular Biology. 84: 327–339. doi:10.1083/jcb.84.2.327. 
  14. ^ Bowling AJ, Brown RM (2008). "The cytoplasmic domain of the cellulose-synthesizing complex in vascular plants". Protoplasma. 233 (1-2): 115–27. doi:10.1007/s00709-008-0302-2. PMID 18709477. 
  15. ^ Robinson DG, White RK, Preston RD (June 1972). "Fine structure of swarmers of Cladophora and Chaetomorpha : III. Wall synthesis and development". Planta. 107 (2): 131–44. doi:10.1007/BF00387719. PMID 24477398. 
  16. ^ a b Richmond T (2000). "Higher plant cellulose synthases". Genome Biology. 1 (4): REVIEWS3001. doi:10.1186/gb-2000-1-4-reviews3001. PMID 11178255. 
  17. ^ a b Heath, IB (1974). "A unified hypothesis for the role of membrane bound enzyme complexes and microtubules in plant cell wall synthesis". Journal of Theoretical Biology. 48: 445–449. doi:10.1016/S0022-5193(74)80011-1. 
  18. ^ Paredez AR, Somerville CR, Ehrhardt DW (June 2006). "Visualization of cellulose synthase demonstrates functional association with microtubules". Science. 312 (5779): 1491–5. doi:10.1126/science.1126551. PMID 16627697. 
  19. ^ Wightman R, Turner SR (June 2008). "The roles of the cytoskeleton during cellulose deposition at the secondary cell wall". The Plant Journal. 54 (5): 794–805. doi:10.1111/j.1365-313X.2008.03444.x. PMID 18266917. 
  20. ^ Green PB (December 1962). "Mechanism for Plant Cellular Morphogenesis". Science. 138 (3548): 1404–5. doi:10.1126/science.138.3548.1404. PMID 17753861. 
  21. ^ Mansoori N, Timmers J, Desprez T, Alvim-Kamei CL, Kamei CL, Dees DC, Vincken JP, Visser RG, Höfte H, Vernhettes S, Trindade LM (2014). "KORRIGAN1 interacts specifically with integral components of the cellulose synthase machinery". PLOS One. 9 (11): e112387. doi:10.1371/journal.pone.0112387. PMID 25383767. 

Further reading[edit]

  • Glaser L (June 1958). "The synthesis of cellulose in cell-free extracts of Acetobacter xylinum". The Journal of Biological Chemistry. 232 (2): 627–36. PMID 13549448.