A Comprehensive Analysis of Interaction and Localization of Arabidopsis SKP1-LIKE (ASK) and F-Box (FBX) Proteins

Abstract

F-Box (FBX) proteins are encoded by a multigene family present in major lineages of eukaryotes. A number of FBX proteins are shown to be subunits of SCF complex, a type of E3 ligases composed of SKP1, CULLIN, FBX and RBX1 proteins. The Arabidopsis SKP-LIKE (ASK) proteins are also members of a family and some of them interact with FBX proteins directly. To clarify how FBX and ASK proteins combine, we carried out a large-scale interaction analysis between FBX and ASK proteins using yeast two-hybrid assay (Y2H) in Arabidopsis thaliana. FBX proteins randomly chosen from those proteins that interacted with more than one ASK protein were further analyzed for their subcellular localization and in vivo interaction with ASK proteins. Furthermore, the expression profiles of FBX and ASK genes were compared. This work reveals that FBX proteins had a preference for interacting with ASK proteins depending on the domains they contain such as the FBX-associated (FBA) domain, the Kelch domain and leucine rich repeat (LRR). In addition, it was found that a single FBX protein could form multiple SCF complexes by interacting with several ASK proteins in many cases. Furthermore, it was suggested that the variation of SCF complexes were especially abundant in tissues related to male gametophyte and seed development. More than half of the FBX proteins studied did not interact with any of the ASK proteins, implying the necessity for certain regulations for their interaction in vivo and/or distinct roles from subunits of the SCF complex.

Cyclin-like F-box protein plays a role in growth and development of the three model species Medicago truncatula, Lotus japonicus, and Arabidopsis thaliana

“…33 Our data confirmed these observations, showing expression of the F-box gene in all plant organs and tissues consisting of actively dividing cells, and during the stages of somatic embryogenesis, thus supporting the role of F-box in the growth and development of the three studied model plants (Figures 1-3). In L. japonicas transcriptional reporter lines, F-box expression was detected in the nodule vasculature ( Figure 2C), but was not observed in the nodules of M. truncatula.…”

Genome-wide analysis of phylogeny, expression profile and sub-cellular localization of SKP1-Like genes in wild tomato

“…Similar to ASK1 and ASK2 in Arabidopsis and OSK1 and OSK20 in rice, SSK1 and SSK2 are broadly expressed in different tissues and their gene products, SSK1 and SSK2, were found to interact with most of the F-box proteins tested here [31,32,36,37]. In addition, phylogenetic analysis indicated that SSK1 and SSK2 were most closely related to ASK1 and ASK2 evolutionarily.…”

“…Yeasts and humans have a single SKP1 gene, while Drosophila, C. elegans contains 7 and 21 SKP1 homologues, respectively [26,29]. In plants, SKP1-like genes have also been identified in several species, including Arabidopsis, rice, wheat and citrus [30][31][32][33][34]. There are 21 putative SKP1 homologues in Arabidopsis genome, denoted as ASK for Arabidopsis SKP1.…”

“…There are 21 putative SKP1 homologues in Arabidopsis genome, denoted as ASK for Arabidopsis SKP1. It has been demonstrated through both yeast two-hybrid assay and bimolecular fluorescence complementation (BiFC) that the 21 ASK proteins displayed substantial differences in their spectrum of interaction with F-box proteins [31,32]. In addition, promoter: GUS reporter analysis, in situ hybridization and RT-PCR revealed that ASK proteins are differentially expressed in various tissues and at various developmental stages [30,35,36].…”

Epigenomic programming contributes to the genomic drift evolution of the F-Box protein superfamily in Arabidopsis

“…Our polymorphism and transcriptome analyses of this superfamily within Arabidopsis further support this scenario with strong evidence that only a subset (∼21%) of FBX loci (mostly Common/High Exp) are under more stringent functional constraints and actively expressed. Notably, the predicted active FBX loci include those known to control important phenotypic responses in Arabidopsis and other species (12) and/or to bind SKP1 (11,30). Most of the remaining FBX loci are under more relaxed selection and, as for pseudogenes, are often expressed at basal levels.…”