The Vr-PLC3 gene encodes a putative plasma membrane-localized phosphoinositide-specific phospholipase C whose expression is induced by abiotic stress in mung bean (Vigna radiata L.).
Phosphoinositide-specific phospholipase C (PI-PLC) catalyzes the hydrolysis of phosphatidylinositol 4,5-bisphosphate to generate inositol 1,4,5-trisphosphate and diacylglycerol, both of which act as secondary messengers in animal cells. In this report, we identified in Vigna radiata L. (mung bean) three distinct partial cDNAs (pVr-PLC1, pVr-PLC2, and pVr-PLC3), which encode forms of putative PI-PLC. All three Vr-PLC genes were transcriptionally active and displayed unique patterns of expression. The Vr-PLC1 and Vr-PLC2 transcripts were constitutively expressed to varying degrees in every tissue of mung bean plants examined. In contrast, the Vr-PLC3 mRNA level was very low under normal growth conditions and was rapidly induced in an abscisic acid-independent manner under environmental stress conditions (drought and high salinity). An isolated genomic clone, about 8.2 kb in length, showed that Vr-PLC1 and Vr-PLC3 are in tandem array in the mung bean genome. The predicted primary sequence of Vr-PLC3 (M(r)=67.4 kDa) is reminiscent of the delta-isoform of animal enzymes which contain core sequences found in typical PI-PLCs, such as the catalytic domain comprising X and Y motifs, a lipid-binding C2 domain, and the less conserved EF-hand domain. Results of in vivo targeting experiment using a green fluorescent protein (GFP) showed that the GFP-Vr-PLC3 fusion protein was localized primarily to the plasma membrane of the Arabidopsis protoplast. The C2 domain was essential for Vr-PLC3 to be targeted to the plasma membrane. The possible biological functions of stress-responsive Vr-PLC3 in mung bean plants are discussed.
Kim
Yun Ju
YJ
Department of Biology, College of Science, Yonsei University, 120-749, Seoul, South Korea
Kim
Jee Eun
JE
Lee
Jae-Hoon
JH
Lee
Myoung Hui
MH
Jung
Ho Won
HW
Bahk
Young Yil
YY
Hwang
Byung Kook
BK
Hwang
Inhwan
I
Kim
Woo Taek
WT
D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000201:enzymology; D017124:Conserved Sequence; D007887:Fabaceae / Q000201:enzymology* / Q000235:genetics*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics; D007700:Kinetics; D008353:Mannitol / Q000494:pharmacology; D008969:Molecular Sequence Data; D043265:Phosphatidylinositol Diacylglycerol-Lyase / Q000096:biosynthesis* / Q000235:genetics*; D054801:Phosphoinositide Phospholipase C; D010802:Phylogeny; D018514:Plant Structures / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology
D007527:Isoenzymes; D012333:RNA, Messenger; D018749:RNA, Plant; D008353:Mannitol; D012965:Sodium Chloride; D054801:Phosphoinositide Phospholipase C; D043265:Phosphatidylinositol Diacylglycerol-Lyase