The Enzyme Database

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EC 1.14.13.169      
Transferred entry: sphinganine C4-monooxygenase. Now EC 1.14.18.5, sphingolipid C4-monooxygenase
[EC 1.14.13.169 created 2012, deleted 2015]
 
 
EC 1.14.18.5     
Accepted name: sphingolipid C4-monooxygenase
Reaction: a dihydroceramide + 2 ferrocytochrome b5 + O2 + 2 H+ = a (4R)-4-hydroxysphinganine ceramide + 2 ferricytochrome b5 + H2O
Other name(s): sphinganine C4-monooxygenase; sphingolipid C4-hydroxylase; SUR2 (gene name); SBH1 (gene name); SBH2 (gene name); DEGS2 (gene name)
Systematic name: dihydroceramide,ferrocytochrome b5:oxygen oxidoreductase (C4-hydroxylating)
Comments: The enzyme, which belongs to the familiy of endoplasmic reticular cytochrome b5-dependent enzymes, is involved in the biosynthesis of sphingolipids in eukaryotes. Some enzymes are bifunctional and also catalyse EC 1.14.19.17, sphingolipid 4-desaturase [4].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Haak, D., Gable, K., Beeler, T. and Dunn, T. Hydroxylation of Saccharomyces cerevisiae ceramides requires Sur2p and Scs7p. J. Biol. Chem. 272 (1997) 29704–29710. [DOI] [PMID: 9368039]
2.  Grilley, M.M., Stock, S.D., Dickson, R.C., Lester, R.L. and Takemoto, J.Y. Syringomycin action gene SYR2 is essential for sphingolipid 4-hydroxylation in Saccharomyces cerevisiae. J. Biol. Chem. 273 (1998) 11062–11068. [DOI] [PMID: 9556590]
3.  Sperling, P., Ternes, P., Moll, H., Franke, S., Zähringer, U. and Heinz, E. Functional characterization of sphingolipid C4-hydroxylase genes from Arabidopsis thaliana. FEBS Lett. 494 (2001) 90–94. [DOI] [PMID: 11297741]
4.  Ternes, P., Franke, S., Zähringer, U., Sperling, P. and Heinz, E. Identification and characterization of a sphingolipid Δ4-desaturase family. J. Biol. Chem. 277 (2002) 25512–25518. [DOI] [PMID: 11937514]
5.  Mizutani, Y., Kihara, A. and Igarashi, Y. Identification of the human sphingolipid C4-hydroxylase, hDES2, and its up-regulation during keratinocyte differentiation. FEBS Lett. 563 (2004) 93–97. [DOI] [PMID: 15063729]
[EC 1.14.18.5 created 2012 as EC 1.14.13.169, transferred 2015 to EC 1.14.18.5]
 
 
EC 1.14.18.6     
Accepted name: 4-hydroxysphinganine ceramide fatty acyl 2-hydroxylase
Reaction: a phytoceramide + 2 ferrocytochrome b5 + O2 + 2 H+ = a (2′R)-2′-hydroxyphytoceramide + 2 ferricytochrome b5 + H2O
Glossary: a phytoceramide = a (4R)-4-hydroxysphinganine ceramide = an N-acyl-4-hydroxysphinganine
Other name(s): FA2H (gene name); SCS7 (gene name)
Systematic name: (4R)-4-hydroxysphinganine ceramide,ferrocytochrome-b5:oxygen oxidoreductase (fatty acyl 2-hydroxylating)
Comments: The enzyme, characterized from yeast and mammals, catalyses the hydroxylation of carbon 2 of long- or very-long-chain fatty acids attached to (4R)-4-hydroxysphinganine during de novo ceramide synthesis. The enzymes from yeast and from mammals contain an N-terminal cytochrome b5 domain that acts as the direct electron donor to the desaturase active site. The newly introduced 2-hydroxyl group has R-configuration. cf. EC 1.14.18.7, dihydroceramide fatty acyl 2-hydroxylase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Mitchell, A.G. and Martin, C.E. Fah1p, a Saccharomyces cerevisiae cytochrome b5 fusion protein, and its Arabidopsis thaliana homolog that lacks the cytochrome b5 domain both function in the α-hydroxylation of sphingolipid-associated very long chain fatty acids. J. Biol. Chem. 272 (1997) 28281–28288. [DOI] [PMID: 9353282]
2.  Dunn, T.M., Haak, D., Monaghan, E. and Beeler, T.J. Synthesis of monohydroxylated inositolphosphorylceramide (IPC-C) in Saccharomyces cerevisiae requires Scs7p, a protein with both a cytochrome b5-like domain and a hydroxylase/desaturase domain. Yeast 14 (1998) 311–321. [DOI] [PMID: 9559540]
3.  Alderson, N.L., Rembiesa, B.M., Walla, M.D., Bielawska, A., Bielawski, J. and Hama, H. The human FA2H gene encodes a fatty acid 2-hydroxylase. J. Biol. Chem. 279 (2004) 48562–48568. [DOI] [PMID: 15337768]
4.  Eckhardt, M., Yaghootfam, A., Fewou, S.N., Zoller, I. and Gieselmann, V. A mammalian fatty acid hydroxylase responsible for the formation of α-hydroxylated galactosylceramide in myelin. Biochem. J. 388 (2005) 245–254. [DOI] [PMID: 15658937]
5.  Guo, L., Zhang, X., Zhou, D., Okunade, A.L. and Su, X. Stereospecificity of fatty acid 2-hydroxylase and differential functions of 2-hydroxy fatty acid enantiomers. J. Lipid Res. 53 (2012) 1327–1335. [DOI] [PMID: 22517924]
[EC 1.14.18.6 created 2015]
 
 
EC 1.14.19.29     
Accepted name: sphingolipid 8-(E/Z)-desaturase
Reaction: (1) a (4R)-4-hydroxysphinganine ceramide + 2 ferrocytochrome b5 + O2 + 2 H+ = a (4R,8E)-4-hydroxysphing-8-enine ceramide + 2 ferricytochrome b5 + 2 H2O
(2) a (4R)-4-hydroxysphinganine ceramide + 2 ferrocytochrome b5 + O2 + 2 H+ = a (4R,8Z)-4-hydroxysphing-8-enine ceramide + 2 ferricytochrome b5 + 2 H2O
Glossary: a (4R)-4-hydroxysphinganine-ceramide = a phytoceramide
(4R)-4-hydroxysphinganine = phytosphinganine
Other name(s): 8-sphingolipid desaturase (ambiguous); 8 fatty acid desaturase (ambiguous); DELTA8-sphingolipid desaturase (ambiguous)
Systematic name: (4R)-4-hydroxysphinganine ceramide,ferrocytochrome b5:oxygen oxidoreductase (8,9 cis/trans-dehydrogenating)
Comments: The enzymes from higher plants convert sphinganine, 4E-sphing-4-enine and phytosphinganine into E/Z-mixtures of Δ8-desaturated products displaying different proportions of geometrical isomers depending on plant species. The nature of the actual desaturase substrate has not yet been studied experimentally. The enzymes contain an N-terminal cytochrome b5 domain that acts as the direct electron donor to the active site of the desaturase [1]. The homologous enzymes from some yeasts and diatoms, EC 1.14.19.18, sphingolipid 8-(E)-desaturase, act on sphing-4-enine ceramides and produce only the trans isomer.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Sperling, P., Zähringer, U. and Heinz, E. A sphingolipid desaturase from higher plants. Identification of a new cytochrome b5 fusion protein. J. Biol. Chem. 273 (1998) 28590–28596. [DOI] [PMID: 9786850]
2.  Sperling, P., Blume, A., Zähringer, U., and Heinz, E. Further characterization of Δ8-sphingolipid desaturases from higher plants. Biochem Soc Trans. 28 (2000) 638–641. [PMID: 11171153]
3.  Sperling, P., Libisch, B., Zähringer, U., Napier, J.A. and Heinz, E. Functional identification of a Δ8-sphingolipid desaturase from Borago officinalis. Arch. Biochem. Biophys. 388 (2001) 293–298. [DOI] [PMID: 11368168]
4.  Beckmann, C., Rattke, J., Oldham, N.J., Sperling, P., Heinz, E. and Boland, W. Characterization of a Δ8-sphingolipid desaturase from higher plants: a stereochemical and mechanistic study on the origin of E,Z isomers. Angew. Chem. Int. Ed. Engl. 41 (2002) 2298–2300. [DOI] [PMID: 12203571]
5.  Ryan, P.R., Liu, Q., Sperling, P., Dong, B., Franke, S. and Delhaize, E. A higher plant Δ8 sphingolipid desaturase with a preference for (Z)-isomer formation confers aluminum tolerance to yeast and plants. Plant Physiol. 144 (2007) 1968–1977. [DOI] [PMID: 17600137]
6.  Chen, M., Markham, J.E. and Cahoon, E.B. Sphingolipid Δ8 unsaturation is important for glucosylceramide biosynthesis and low-temperature performance in Arabidopsis. Plant J. 69 (2012) 769–781. [DOI] [PMID: 22023480]
[EC 1.14.19.29 created 2015]
 
 


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