Quantitative Proteomics and Phosphoproteomics Supports a Role for Mut9-Like Kinases in Multiple Metabolic and Signaling Pathways inArabidopsis

Abstract

25Protein phosphorylation is one of the most prevalent post-translational modifications found in 26 eukaryotic systems and serves as a key molecular mechanism by which protein function is 27 regulated in response to environmental stimuli. The Mut9-Like Kinases (MLKs) are a plant-specific 28 family of Ser/Thr kinases that have been linked to light, circadian, and abiotic stress signaling. 29Here we use quantitative phosphoproteomics in conjunction with global proteomic analysis to 30 explore the role of the MLKs in daily protein dynamics. In the absence of MLK family kinases, 31 proteins involved in light, circadian, and hormone signaling as well as several chromatin modifying 32 enzymes were found to have altered phosphorylation profiles. Additionally, mlk mutant seedlings 33 were found to have elevated glucosinolate accumulation and increased sensitivity to DNA 34 damage. Our analysis in combination with previously reported data supports the involvement of 35