Forzani C, Carreri A, de la Fuente van Bentem S, Lecourieux D, Lecourieux F, Hirt H

In Arabidopsis thaliana the serine/threonine protein kinase oxidative signal-inducible1 (OXI1), mediates oxidative stress signalling. Its activity is required for the full activation of the mitogen-activated protein kinases (MAPKs), MPK3 and MPK6 in response to oxidative stress. In addition, the serine/threonine protein kinase PTI1-2 has been positioned downstream from OXI1 but ...

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whether PTI1-2 signals through MAPK cascades is unclear. Using a yeast two-hybrid screen we show that OXI1 also interacts with PTI1-4. OXI1 and PTI1-4 are stress-responsive genes and are expressed in the same tissues. Therefore, studies were undertaken to determine whether PTI1-4 is positioned in the OXI1/MAPK signalling pathway. The interaction between OXI1 and PTI1-4 was confirmed by using in vivo co-immunoprecipitation experiments. OXI1 as well as PTI1-4 were substrates of MPK3 and MPK6 in vitro. Whereas no direct interaction was detected between MPK3, MPK6 and OXI1, in vitro binding studies showed an interaction between MPK3, MPK6 and PTI1-4. In addition, PTI1-4 and MPK6 were found in vivo in the same protein complex. These results demonstrate that PTI1-4 signals via OXI1 and MPK6 signalling cascades.

Date: Jan. 29, 2011

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