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. 2004 Apr;134(4):1332-6.
doi: 10.1104/pp.103.037275.

Mastoparan rapidly activates plant MAP kinase signaling independent of heterotrimeric G proteins

Godfrey P Miles  1 , Marcus A Samuel, Alan M Jones, Brian E Ellis
Affiliations

Mastoparan rapidly activates plant MAP kinase signaling independent of heterotrimeric G proteins

Godfrey P Miles et al. Plant Physiol. 2004 Apr.
No abstract available

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Figures

Figure 1.
Figure 1.
MP, ozone, and UVC induced the activation of MAPKs in wild-type and heterotrimeric (Gα, gpa1-2 and Gβ, agb1-2) loss-of-function Arabidopsis seedlings. a, To ascertain if MP is capable of inducing the activation of an Arabidopsis MAPK, extracted proteins (40 μg) from MP-treated (5 μm for 5 min) samples, both crude and immunoprecipitated (using specific anti-AtMPK6 antibodies) were assayed for in-gel kinase activity. MBP-phosphorylation was detected in both the crude and immunoprecipitated samples but absent from the control cells. b and c, Seedlings were treated with MP or Mas-17 (5 μm, 5 min), ozone (200 ppb, 10 min), or UVC (10 J M−2, total energy) and harvested as described earlier. Control tissue was from seedlings exposed to ambient air (ozone or UVC) or treated with water, the vehicle used for the MP solution. Protein (40 μg) extracts prepared from 2-week-old leaf tissue, isolated from MP-, ozone-, and UVC- exposed wild-type and heterotrimeric G protein loss-of-function seedlings, were resolved on a 10% SDS-polyacrylamide gel, blotted and probed with anti-pERK 1&2 antibodies (primary antibodies). Columbia wild-type seedlings, when treated with MP (5 μm, 5 min), ozone (200 ppb, 10 min), or UVC (10 J M−2, total energy), gave the same results as the parental (wild-type) ecotype Wassilewskija seedlings (data not shown). All experiments were performed in triplicate.
Figure 2.
Figure 2.
MP, but not the less active analog (Mas-17), rapidly activates an MAP kinase in wild-type tobacco suspension-cultured cells. a, Extracted proteins (40 μg) from these same samples were immunoprecipitated using specific anti-SIPK antibodies (5 μg), and the precipitate was assayed for in-gel kinase activity. MBP-phosphorylation was evident in MP-treated (5 μm for 1 min) tobacco cells, but absent from Mas-17 treated cells. Control cells were treated with water, the vehicle for MP treatment. UVC-irradiated tobacco cells also displayed MBP-phosphorylation activity and extracts of these cells were used as an in-gel size standard. Protein extracts from both controls, MP- and UVC-exposed cells, were analyzed by the MAPK phosphorylation assay. b, MP-induced activation of SIPK is dependent on Ca2+ ions, and an upstream MAPKK. Protein extracts (20 μg) from suspension-cultured tobacco cells that had been pretreated with either La3+ (5 mm, 15 min), or the MEK 1&2 inhibitor, PD98059 (100 μm, 60 min) or followed by MP treatment (5 μm, 1 min) were analyzed via immunoblotting using anti-pERK 1&2 antibodies. Pretreatment of tobacco suspension cultured cells with either La3+ or PD interdicted the ability of MP to induce the activation of SIPK. c, The Coomassie Brilliant Blue-stained membrane is used as a loading control. d, MP-induced activation of SIPK was also inhibited by pretreatment of the tobacco suspension-cultured cells with MPG (10 or 20 mM, 60 min) as detected by anti-pERK1&2 antibodies. All experiments were performed in triplicate.
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