Reaction: a (4E)-sphing-4-enine ceramide + 2 ferrocytochrome b5 + O2 + 2 H+ = a (4E,8E)-sphing-4,8-dienine ceramide + 2 ferricytochrome b5 + 2 H2O
Other name(s): 8-sphingolipid desaturase (ambiguous); 8 fatty acid desaturase (ambiguous); DELTA8-sphingolipid desaturase (ambiguous)
Systematic name: (4E)-sphing-4-enine ceramide,ferrocytochrome b5:oxygen oxidoreductase (8,9-trans dehydrogenating)
Comments: The enzyme, characterized from the yeasts Kluyveromyces lactis and Candida albicans [1] and from the diatom Thalassiosira pseudonana [2], introduces a trans double bond at the 8-position of sphingoid bases in sphingolipids. The enzyme determines the position of the double bond by its distance from the alcohol end of the sphingoid base, and contains a cytochrome b5 domain that acts as the direct electron donor to the active site of the desaturase [3]. The homologous enzymes from higher plants, EC 1.14.19.29, sphingolipid 8-(E/Z)-desaturase, act on phytosphinganine (4-hydroxysphinganine) and produces a mixture of trans and cis isomers.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Takakuwa, N., Kinoshita, M., Oda, Y. and Ohnishi, M. Isolation and characterization of the genes encoding Δ8-sphingolipid desaturase from Saccharomyces kluyveri and Kluyveromyces lactis. Curr. Microbiol. 45 (2002) 459-461. [PMID: 12402089]
2. Tonon, T., Sayanova, O., Michaelson, L.V., Qing, R., Harvey, D., Larson, T.R., Li, Y., Napier, J.A. and Graham, I.A. Fatty acid desaturases from the microalga Thalassiosira pseudonana. FEBS J. 272 (2005) 3401-3412. [PMID: 15978045]
3. Oura, T. and Kajiwara, S. Disruption of the sphingolipid Δ8-desaturase gene causes a delay in morphological changes in Candida albicans. Microbiology 154 (2008) 3795-3803. [PMID: 19047747]