The Arabidopsis thaliana mitogen‐activated protein kinases MPK3 and MPK6 target a subclass of 'VQ‐motif'‐containing proteins to regulate immune responses. Issue 2 (22nd April 2014)

• Record Type: Journal Article
• Authors: Pecher, Pascal; Eschen‐Lippold, Lennart; Herklotz, Siska; Kuhle, Katja; Naumann, Kai; Bethke, Gerit; Uhrig, Joachim; Weyhe, Martin; Scheel, Dierk; Lee, Justin
• Is Part Of: New phytologist. Volume 203:Issue 2(2014)
• Page Start: 592
• Page End: 606
• Publication Date: 2014-04-22
• Subjects: Botany -- Periodicals; 580
• DOI: 10.1111/nph.12817
• Languages: English
• ISSNs: 0028-646X

Abstract

<abstract abstract-type="main" id="nph12817-abs-0001"> <title>Summary</title> <p> <list id="nph12817-list-0001" list-type="bullet"> <list-item> <p>Mitogen‐activated protein kinase (MAPK) cascades play key roles in plant immune signalling, and elucidating their regulatory functions requires the identification of the pathway‐specific substrates.</p> </list-item> <list-item> <p>We used yeast two‐hybrid interaction screens, <italic>in vitro</italic> kinase assays and mass spectrometry‐based phosphosite mapping to study a family of MAPK substrates. Site‐directed mutagenesis and promoter‐reporter fusion studies were performed to evaluate the impact of substrate phosphorylation on downstream signalling.</p> </list-item> <list-item> <p>A subset of the <italic>Arabidopsis thaliana </italic>VQ‐motif‐containing proteins (VQPs) were phosphorylated by the MAPKs MPK3 and MPK6, and renamed MPK3/6‐targeted VQPs (MVQs). When plant protoplasts (expressing these MVQs) were treated with the flagellin‐derived peptide flg22, several MVQs were destabilized <italic>in vivo</italic>. The MVQs interact with specific WRKY transcription factors. Detailed analysis of a representative member of the MVQ subset, MVQ1, indicated a negative role in WRKY‐mediated defence gene expression – with mutation of the VQ‐motif abrogating WRKY binding and causing mis‐regulation of defence gene expression.</p> </list-item> <list-item> <p>We postulate the existence of a variety of WRKY‐VQP‐containing transcriptional regulatory protein complexes that depend on spatio‐temporal <italic>VQP</italic> and <italic>WRKY</italic> expression patterns. Defence gene transcription can be modulated by changing the composition of these complexes – in part – through MAPK‐mediated VQP degradation.</p> </list-item> </list> </p> </abstract>