title: Arabidopsis mutants lacking long chain base phosphate lyase are fumonisin-sensitive and accumulate trihydroxy-18:1 long chain base phosphate.
abstract: The sphingoid long chain bases (LCBs) and their phosphorylated derivatives (LCB-Ps) are important signaling molecules in eukaryotic organisms. The cellular levels of LCB-Ps are tightly controlled by the coordinated action of the LCB kinase activity responsible for their synthesis and the LCB-P phosphatase and lyase activities responsible for their catabolism. Although recent studies have implicated LCB-Ps as regulatory molecules in plants, in comparison with yeast and mammals, much less is known about their metabolism and function in plants. To investigate the functions of LCB-Ps in plants, we have undertaken the identification and characterization of Arabidopsis genes that encode the enzymes of LCB-P metabolism. In this study the Arabidopsis At1g27980 gene was shown to encode the only detectable LCB-P lyase activity in Arabidopsis. The LCB-P lyase activity was characterized, and mutant plant lines lacking the lyase were generated and analyzed. Whereas in other organisms loss of LCB-P lyase activity is associated with accumulation of high levels of LCB/LCB-Ps and developmental abnormalities, the sphingolipid profiles of the mutant plants were remarkably similar to those of wild-type plants, and no developmental abnormalities were observed. Thus, these studies indicate that the lyase plays a minor role in maintenance of sphingolipid metabolism during normal plant development and growth. However, a clear role for the lyase was revealed upon perturbation of sphingolipid synthesis by treatment with the inhibitor of ceramide synthase, fumonisin B(1).
authors.affiliation: Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20184, USA.
authors.forename: Yoseph
authors.initials: Y
authors.lastname: Tsegaye
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Richardson
authors.forename: Janis E
authors.initials: JE
authors.lastname: Bravo
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: Mulcahy
authors.forename: Daniel V
authors.initials: DV
authors.lastname: Lynch
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Markham
authors.forename: Jan G
authors.initials: JG
authors.lastname: Jaworski
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: Edgar B
authors.initials: EB
authors.lastname: Cahoon
authors.forename: Teresa M
authors.initials: TM
authors.lastname: Dunn
mesh_terms: D000446:Aldehyde-Lyases / Q000235:genetics* / Q000502:physiology; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D037341:Fumonisins / Q000737:chemistry / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D018506:Gene Expression Regulation, Plant; D008861:Microsomes / Q000378:metabolism; D008956:Models, Chemical; D008969:Molecular Sequence Data; D009154:Mutation; D010710:Phosphates; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013107:Sphingolipids / Q000737:chemistry
chemical_list: D029681:Arabidopsis Proteins; D037341:Fumonisins; D005656:Fungal Proteins; D010710:Phosphates; D013107:Sphingolipids; C056933:fumonisin B1; D000446:Aldehyde-Lyases; C523687:At1g27980 protein, Arabidopsis