Distinct regulation of salinity and genotoxic stress responses by Arabidopsis MAP kinase phosphatase 1.
The Arabidopsis genome contains 20 genes encoding mitogen-activated protein kinases (MAPKs), which drastically outnumbers genes for their negative regulators, MAP kinase phosphatases (MKPs) (five at most). This contrasts sharply with genomes of other eukaryotes where the number of MAPKs and MKPs is approximately equal. MKPs may therefore play an important role in signal integration in plants, through concerted regulation of several MAPKs. Our previous studies identified Arabidopsis MKP1 and showed that its deficiency in the mkp1 mutant results in plant hypersensitivity to genotoxic stress. Here, we identify a set of MAPKs that interact with MKP1, and show that the activity level of one of these, MPK6, is regulated by MKP1 in vivo. Moreover, using expression profiling, we identified a specific group of genes that probably represent targets of MKP1 regulation. Surprisingly, the identity of these genes and interacting MAPKs suggested involvement of MKP1 in salt stress responses. Indeed, mkp1 plants have increased resistance to salinity. Thus MKP1 apparently plays a pivotal role in the integration and fine-tuning of plant responses to various environmental challenges.
Ulm
Roman
R
Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland. roman.ulm@biologie.uni-freiburg.de
Ichimura
Kazuya
K
Mizoguchi
Tsuyoshi
T
Peck
Scott C
SC
Zhu
Tong
T
Wang
Xun
X
Shinozaki
Kazuo
K
Paszkowski
Jerzy
J
D017360:Arabidopsis / Q000201:enzymology*; D020134:Catalytic Domain / Q000502:physiology; D018797:Cell Cycle Proteins; D017124:Conserved Sequence; D054638:Dual Specificity Phosphatase 1; D017874:Immediate-Early Proteins / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D017027:Protein Tyrosine Phosphatases / Q000502:physiology*; D012462:Saline Solution, Hypertonic; D015398:Signal Transduction / Q000502:physiology*; D014466:Ultraviolet Rays
D018797:Cell Cycle Proteins; D017874:Immediate-Early Proteins; D012462:Saline Solution, Hypertonic; D020928:Mitogen-Activated Protein Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054638:Dual Specificity Phosphatase 1; D017027:Protein Tyrosine Phosphatases