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Heterotrimeric G‐protein complex and G‐protein‐coupled receptor from a legume ( Pisum sativum ): role in salinity and heat stress and cross‐talk with phospholipase C
Author(s) -
Misra Shikha,
Wu Yuliang,
Venkataraman Gayatri,
Sopory Sudhir K.,
Tuteja Narendra
Publication year - 2007
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2007.03169.x
Subject(s) - heterotrimeric g protein , g protein coupled receptor , g protein , biology , g beta gamma complex , phospholipase c , gq alpha subunit , protein subunit , g protein coupled receptor kinase , biochemistry , microbiology and biotechnology , receptor , gene
Summary Heterotrimeric G‐proteins transduce signals from activated G‐protein‐coupled receptors (GPCR) to appropriate downstream effectors and thereby play an important role in signaling. A role of G‐proteins in salinity and heat stress tolerance has not heretofore been described. We report isolation of cDNAs of two isoforms of Gα (Gα1, 1152 bp; Gα2, 1152 bp), one Gβ (1134 bp), two isoforms of Gγ (Gγ1, 345 bp; Gγ2, 303 bp) and a GPCR (1008 bp) from Pisum sativum , and purification of all the encoded recombinant proteins (Gα, 44 kDa; Gβ, 41 kDa; Gγ, 14 kDa; GPCR, 35 kDa). The transcript levels of Gα and Gβ were upregulated following NaCl, heat and H 2 O 2 treatments. Protein–protein interaction studies using an in vitro yeast two‐hybrid system and in planta co‐immunoprecipitation showed that the Gα subunit interacted with the pea Gβ subunit and pea phospholipase C (PLCδ) at the calcium‐binding domain (fn1). The GTPase activity of the Gα subunit increased after interaction with PLCδ. The GPCR protein interacted with all the subunits of G‐proteins and with itself. Transgenic tobacco plants (T 0 and T 1 ) constitutively over‐expressing Gα showed tolerance to salinity and heat, while Gβ‐over‐expressing plants showed only heat tolerance, as tested by leaf disk senescence assay and germination/growth of T 1 seeds/seedlings. These findings provide direct evidence for a novel role of Gα and Gβ subunits in abiotic stress tolerance and possible cross‐talk between PLC‐ and G‐protein‐mediated signaling pathways.