Journal Article

Characterization of Phosphatidylinositol-Specific Phospholipase C (PI-PLC) from <i>Lilium</i> <i>daviddi</i> Pollen

Yan-Yun Pan, Xin Wang, Li-Geng Ma and Da-Ye Sun

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 46, issue 10, pages 1657-1665
Published in print October 2005 | ISSN: 0032-0781
Published online October 2005 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pci181
Characterization of Phosphatidylinositol-Specific Phospholipase C (PI-PLC) from Lilium daviddi Pollen

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  • Plant Sciences and Forestry

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The phosphatidylinositol-specific phospholipase C (PI-PLC) activity is detected in purified Lilium pollen protoplasts. Two PI-PLC full length cDNAs, LdPLC1 and LdPLC2, were isolated from pollen of Lilium daviddi. The amino acid sequences for the two PI-PLCs deduced from the two cDNA sequences contain X, Y catalytic motifs and C2 domains. Blast analysis shows that LdPLCs have 60–65% identities to the PI-PLCs from other plant species. Both recombinant PI-PLCs proteins expressed in E. coli cells show the PIP2-hydrolyzing activity. The RT-PCR analysis shows that both of them are expressed in pollen grains, whereas expression level of LdPLC2 is induced in germinating pollen. The exogenous purified calmodulin (CaM) is able to stimulate the activity of the PI-PLC when it is added into the pollen protoplast medium, while anti-CaM antibody suppresses the stimulation effect caused by exogenous CaM. PI-PLC activity is enhanced by G protein agonist cholera toxin and decreased by G protein antagonist pertussis toxin. Increasing in PI-PLC activity caused by exogenous purified CaM is also inhibited by pertussis toxin. A PI-PLC inhibitor, U-73122, inhibited the stimulation of PI-PLC activity caused by cholera toxin and it also leads to the decrease of [Ca2+]cyt in pollen grains. Those results suggest that the PPI-PLC signaling pathway is present in Lilium daviddi pollen, and PI-PLC activity might be regulated by a heterotrimeric G protein and extracellular CaM.

Keywords: cDNA cloning; Extracellular calmodulin (CaM); Heterotrimeric G protein; Lilium daviddi pollen; Phosphatidylinositol-specific phospholipase C; CaM, calmodulin; CTX, cholera toxin; DAG, diacylglycerol; IP3, inositol-1,4,5-trisphosphate; IP3R, IP3 receptor; PI-PLC, phosphoinositide-specific phospholipase C; PIP2, phosphatidylinositol-4,5-bisphosphate; PTX, pertussis toxin; U73122, (1-[6-([(17β)-3-Methoxyestra-1,3,5(10)-trien-17yl]amino)hexyl]-1H-pyrrole-2,5-dione); U73343, (1-[6-(-[(17β)-3-methoxyestra-1,3,5(10)-trien-17yl]amino)hexyl]-2,5-pyrrolidinedione)

Journal Article.  6605 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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