Affiliations 

  • 1 Department of Plant Agriculture, University of Guelph, Guelph, Ontario, N1G 2W1, Canada; Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
  • 2 Department of Plant Agriculture, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
  • 3 Department of Plant Agriculture, University of Guelph, Guelph, Ontario, N1G 2W1, Canada; Ontario Ministry of Agriculture, Food and Rural Affairs, Simcoe Research Station, Ontario, Canada
  • 4 Department of Plant Agriculture, University of Guelph, Guelph, Ontario, N1G 2W1, Canada. Electronic address: gpaliyat@uoguelph.ca
Plant Physiol Biochem, 2020 Mar;148:180-192.
PMID: 31972387 DOI: 10.1016/j.plaphy.2020.01.014

Abstract

Phosphatidylinositol 3-kinases (PI3Ks) are characterized by the presence of a C2 domain at the N-terminal end (class I, III); or at both the N-terminal and C-terminal ends (class II), sometimes including a Plextrin homology domain and/or a Ras domain. Plant PI3Ks are analogous to the class III mammalian PI3K. An N-terminal fragment (~170 aa) of the tomato PI3K regulatory domain including the C2 domain, was cloned and expressed in a bacterial system. This protein was purified to homogeneity and its physicochemical properties analyzed. The purified protein showed strong binding with monophosphorylated phosphatidylinositols, and the binding was dependent on calcium ion concentration and pH. In the overall tertiary structure of PI3K, C2 domain showed unique characteristics, having three antiparallel beta-sheets, hydrophobic regions, acidic as well as alkaline motifs, that can enable its membrane binding upon activation. To elucidate the functional significance of C2 domain, transgenic tobacco plants expressing the C2 domain of PI3K were generated. Transgenic plants showed defective pollen development and disrupted seed set. Flowers from the PI3K-C2 transgenic plants showed delayed wilting, and a decrease in ethylene production. It is likely that introduction of the PI3K-C2 segment may have interfered with the normal binding of PI3K to the membrane, delaying the onset of membrane lipid catabolism that lead to senescence.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.