Arabidopsis mutants lacking long chain base phosphate lyase are fumonisin-sensitive and accumulate trihydroxy-18:1 long chain base phosphate.
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).
Tsegaye
Yoseph
Y
Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20184, USA.
Richardson
Christopher G
CG
Bravo
Janis E
JE
Mulcahy
Brendan J
BJ
Lynch
Daniel V
DV
Markham
Jennifer E
JE
Jaworski
Jan G
JG
Chen
Ming
M
Cahoon
Edgar B
EB
Dunn
Teresa M
TM
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
D029681:Arabidopsis Proteins; D037341:Fumonisins; D005656:Fungal Proteins; D010710:Phosphates; D013107:Sphingolipids; C056933:fumonisin B1; D000446:Aldehyde-Lyases; C523687:At1g27980 protein, Arabidopsis