Functional characterization of sphingolipid C4-hydroxylase genes from Arabidopsis thaliana.
In the genome of Arabidopsis thaliana, two genes were identified encoding isoenzymes for C4-hydroxylation of long chain bases (LCB) in plant sphingolipids. Both predicted proteins consist of 258 amino acid residues (77% identity) which show sequence similarity to di-iron-binding enzymes, such as Sur2p and Erg3p from yeast, involved in oxygen-dependent lipid modifications. Heterologous expression of these genes in a yeast sur2Delta-null mutant lacking C4-LCB hydroxylation resulted in the formation of D-ribo-C(18)- and -C(20)-phytosphinganine. The identity and stereochemical configuration of the isolated trihydroxybases was confirmed by electrospray ionization-mass spectroscopy, gas-liquid chromatography-mass spectrometry and 1H-nuclear magnetic resonance spectroscopy. These results represent the first functional identification of SUR2 genes from plants as well as from any organism other than yeast.
Sperling
P
P
Institut für Allgemeine Botanik, Universität Hamburg, Germany.
Ternes
P
P
Moll
H
H
Franke
S
S
Zähringer
U
U
Heinz
E
E
D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D018744:DNA, Plant; D044943:Fatty Acid Desaturases / Q000235:genetics; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D017343:Genes, Plant / Q000502:physiology*; D006899:Mixed Function Oxygenases / Q000235:genetics*; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013110:Sphingosine / Q000031:analogs & derivatives / Q000096:biosynthesis*
D018744:DNA, Plant; D029701:Saccharomyces cerevisiae Proteins; D006899:Mixed Function Oxygenases; C109313:SUR2 protein, S cerevisiae; D044943:Fatty Acid Desaturases; C012491:phytosphingosine; D013110:Sphingosine