Abstract
A recent report has indicated that heterotrimeric G-proteins are downstream elements in the sphingosine 1-phospate (S1P) signaling pathway that mediates an ABA regulation of stomatal function. Thus controlling the levels of S1P is likely to be an important event in plant cellular processes. S1P is resolved into ethanolamine phosphate and C16-fatty aldehyde, which is catalyzed by sphingosine phosphate lyase (SPL). In this study, we isolated and characterized a SPL gene from Arabidopsis thaliana. Using the human SPL amino acid sequence (NM_003901), we identified a putative A. thaliana SPL sequence. Alignment of the deduced amino acid sequences of different SPL proteins shows the sequence from A. thaliana shares 43% and 40% identity with those from human and S. cerevisiae, respectively. We also found that A. thaliana SPL contains a predicted pyridoxal 5'-phosphate binding site, which is conserved in human and S. cerevisiae SPL.
