Activation of a nuclear-localized SIPK in tobacco cells challenged by cryptogein, an elicitor of plant defence reactions

作者：Dahan Jennifer; Pichereaux Carole; Rossignol Michel; Blanc Sabrina; Wendehenne David; Pugin Alain; Bourque Stephane^*

来源：Biochemical Journal, 2009, 418(1): 191-200.

DOI：10.1042/BJ20081465

• cryptogein
• plant defence
• protein kinase
• salicylic acid-induced protein kinase (SIPK)
• tobacco cell

When a plant cell is challenged by a well-defined stimulus, complex signal transduction pathways are activated to promote the modulation of specific sets of genes and eventually to develop adaptive responses. In this context, protein phosphorylation plays, H fundamental role through the activation of multiple protein kinase families. Although the involvement of protein kinases at the plasma membrane and cytosolic levels are now well-documented, their nuclear counterparts are still poorly investigated. In the field of plant defence reactions, no known study has yet reported the activation of a nuclear protein kinase and/or its nuclear activity in plant cells, although some protein kinases, e.g. MAPK (mitogen-activated protein kinase), are known to be translocated into the nucleus. In the present study, we investigated the ability of cryptogein, a proteinaceous elicitor of tobacco defence reactions, to induce different nuclear protein kinase activities. We found that at least four nuclear protein kinases are activated in response to cryptogein treatment in a time-dependent manner, some of them exhibiting Ca(2 )-dependent activity. The present study focused on one 47 kDa protein kinase with a Ca(2 )-independent activity, closely related to the MAPK family. After purification and microsequencing, this protein kinase was formally identified as SIPK (salicyclic acid-induced protein kinase), a biotic and abiotic stress-activated MAPK of tobacco. We also showed that cytosolic activation of SIPK is not sufficient to promote a nuclear SIPK activity, the latter being correlated with cell death. In that way, the present study provides evidence of a functional nuclear MAPK activity involved in response to an elicitor treatment.

• 出版日期2009-2-15