Arabidopsis MKS1 is involved in basal immunity and requires an intact N-terminal domain for proper function

TY - JOUR

T1 - Arabidopsis MKS1 is involved in basal immunity and requires an intact N-terminal domain for proper function

AU - Petersen, Klaus

AU - Qiu, Jin-Long

AU - Lütje, Juri

AU - Fiil, Berthe Katrine

AU - Hansen, Sidsel

AU - Mundy, John

AU - Petersen, Morten

PY - 2010/1/1

Y1 - 2010/1/1

N2 - Background: Innate immune signaling pathways in animals and plants are regulated by mitogen-activated protein kinase (MAPK) cascades. MAP kinase 4 (MPK4) functions downstream of innate immune receptors via a nuclear substrate MKS1 to regulate the activity of the WRKY33 transcription factor, which in turn controls the production of anti-microbial phytoalexins. Methodology/Principal Findings: We investigate the role of MKS1 in basal resistance and the importance of its N- and Cterminal domains for MKS1 function. We used the information that mks1 loss-of-function partially suppresses the mpk4 lossof- function phenotype, and that transgenic expression of functional MKS1 in mpk4/mks1 double mutants reverted the mpk4 dwarf phenotype. Transformation of mks1/mpk4 with mutant versions of MKS1 constructs showed that a single amino acid substitution in a putative MAP kinase docking domain, MKS1-L32A, or a truncated MKS1 version unable to interact with WRKY33, were deficient in reverting the double mutant to the mpk4 phenotype. These results demonstrate functional requirement in MKS1 for the interaction with MPK4 and WRKY33. In addition, nuclear localization of MKS1 was shown to depend on an intact N-terminal domain. Furthermore, loss-of-function mks1 mutants exhibited increased susceptibility to strains of Pseudomonas syringae and Hyaloperonospora arabidopsidis, indicating that MKS1 plays a role in basal defense responses. Conclusions: Taken together, our results indicate that MKS1 function and subcellular location requires an intact N-terminus important for both MPK4 and WRKY33 interactions.

AB - Background: Innate immune signaling pathways in animals and plants are regulated by mitogen-activated protein kinase (MAPK) cascades. MAP kinase 4 (MPK4) functions downstream of innate immune receptors via a nuclear substrate MKS1 to regulate the activity of the WRKY33 transcription factor, which in turn controls the production of anti-microbial phytoalexins. Methodology/Principal Findings: We investigate the role of MKS1 in basal resistance and the importance of its N- and Cterminal domains for MKS1 function. We used the information that mks1 loss-of-function partially suppresses the mpk4 lossof- function phenotype, and that transgenic expression of functional MKS1 in mpk4/mks1 double mutants reverted the mpk4 dwarf phenotype. Transformation of mks1/mpk4 with mutant versions of MKS1 constructs showed that a single amino acid substitution in a putative MAP kinase docking domain, MKS1-L32A, or a truncated MKS1 version unable to interact with WRKY33, were deficient in reverting the double mutant to the mpk4 phenotype. These results demonstrate functional requirement in MKS1 for the interaction with MPK4 and WRKY33. In addition, nuclear localization of MKS1 was shown to depend on an intact N-terminal domain. Furthermore, loss-of-function mks1 mutants exhibited increased susceptibility to strains of Pseudomonas syringae and Hyaloperonospora arabidopsidis, indicating that MKS1 plays a role in basal defense responses. Conclusions: Taken together, our results indicate that MKS1 function and subcellular location requires an intact N-terminus important for both MPK4 and WRKY33 interactions.

KW - Arabidopsis

KW - Arabidopsis Proteins

KW - Genotype

KW - Immune System

KW - MAP Kinase Signaling System

KW - Microscopy, Confocal

KW - Mitogen-Activated Protein Kinases

KW - Mutagenesis, Site-Directed

KW - Mutation

KW - Phenotype

KW - Phosphoproteins

KW - Plant Physiological Phenomena

KW - Plasmids

KW - Protein Structure, Tertiary

KW - Transcription Factors

KW - Two-Hybrid System Techniques

U2 - 10.1371/journal.pone.0014364

DO - 10.1371/journal.pone.0014364

M3 - Journal article

C2 - 21203436

SN - 1932-6203

VL - 5

SP - e14364

JO - P L o S One

JF - P L o S One

IS - 12

ER -