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Title: Generation of a fertile ask1 mutant uncovers a comprehensive set of SCF‐mediated intracellular functions

Many eukaryotic intracellular processes employ protein ubiquitylation by ubiquitin E3 ligases for functional regulation or protein quality control. In plants, the multi‐subunit Skp1–Cullin1–F‐box (SCF) complexes compose the largest group of E3 ligases whose specificity is determined by a diverse array of F‐box proteins. Although both sequence divergence and polymorphism ofF‐boxgenes well support a broad spectrum of SCF functions, experimental evidence is scarce due to the low number of identified SCF substrates. Taking advantage of the bridge role of Skp1 between F‐box and Cullin1 in the complex, we systematically analyzed the functional influence of a well‐characterizedArabidopsis Skp1‐Like1(ASK1)Dsinsertion allele,ask1, in different Arabidopsis accessions. Through 10 generations of backcrossing with Columbia‐0 (Col‐0), we partially rescued the fertility of this otherwise sterileask1allele in Landsbergerecta, thus providing experimental evidence showing the polymorphic roles of SCF complexes. Thisask1mutant produces twisted rosette leaves, a reduced number of petals, fewer viable pollen grains, and larger embryos and seeds compared to Col‐0. RNA‐Seq‐based transcriptome analysis ofask1uncovered a large spectrum of SCF functions, which is greater than a 10‐fold increase compared with previous studies. We also identified its hyposensitive responses to auxin and abscisic acid treatments and enhanced far‐red light/phyA‐mediated photomorphogenesis. Such diverse roles are consistent with the 20–30% reduction of ubiquitylation events inask1estimated by immunoblotting analysis in this work. Collectively, we conclude that ASK1 is a predominant Skp1 protein in Arabidopsis and that the fertileask1mutant allowed us to uncover a comprehensive set of SCF functions.

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Journal Name:
The Plant Journal
Page Range / eLocation ID:
p. 493-509
Medium: X
Sponsoring Org:
National Science Foundation
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