Xiao Zhu with Dr. Richard Vierstra and Xiaohua Zheng

UW-Madison Departments of Genetics

The ubiquitin (Ub) 26S proteasome pathway in higher eukaryotes is mainly responsible for the selective protein degradation. Via a three-step enzymatic reaction (E1, E2, E3), Ub molecules were covalently attached to the target proteins, which were further sent to proteasome to be broken into small peptide. In this process, E3 Ub ligases recognize the targets and catalyze the Ub transfer. One important type of E3 is known as Skp1-Cullin-F-Box (SCF) complex. The F-Box protein, which binds with Skp1 through its N-terminal F-Box motif, serves as target recognition module by protein-protein interaction. Nearly 700 F-Box proteins were identified in the model plant Arabidopsis thaliana. Mounting studies implicate that F-Box proteins play various roles in the growth and development of Arabidopsis thaliana, yet the distinct functions of the majority of F-Box proteins remain unknown. In an attempt to investigate the novel functions of the F-Box proteins, a large collection of F-Box T-DNA insertion mutants were previously generated. 4 different mutant alleles representing 3 distinct F-Box genes were subject to conditional tests for phenotype screen. Various plant hormones including abscisic acid (ABA), auxin, cytokinin, ethylene, jasmonic acid, brassinosteroid and the chemical cycloheximide (CHX) were used to explore phenotypic dissimilarity between wild type and mutants. No striking phenotypic difference has been detected between the control plant and the mutants in treated conditions by far, suggesting that these three genes may not participate in the hormone pathway and CHX regulated protein synthesis mentioned above.