Skp1-Cullin1-F-box MAX2 E3 ubiquitin ligase complex (SCF(MAX2))

The SCFMAX2 E3 ubiquitin ligase complex is a multi-subunit enzyme in plants that plays a central role in the perception and transduction of strigolactone (SL) and karrikin (KAR) signals (Martín-Fontecha et al., 2024). It consists of the scaffold protein Cullin1 (CUL1), the adaptor protein Skp1 (ASK1 in Arabidopsis), and the F-box protein MAX2 (More Axillary Growth 2), which provides substrate specificity (Stirnberg et al., 2007). Upon binding of strigolactones to the receptor DWARF14 (D14), the receptor undergoes a conformational change that promotes its interaction with the SCFMAX2 complex (Tal et al., 2022). This leads to the polyubiquitination and subsequent 26S proteasome-mediated degradation of transcriptional repressors such as SMXL6, SMXL7, and SMXL8 (Martín-Fontecha et al., 2024). This degradation relieves the repression of downstream genes, thereby regulating various aspects of plant architecture, including shoot branching, root development, and interactions with soil microbes (Tal et al., 2022). In agriculture, this complex is a target for developing strigolactone analogs to induce "suicidal germination" of parasitic weeds like Striga, which cause significant crop losses (Biorxiv, 2024). The complex also integrates signals from other hormones like abscisic acid and auxin to optimize plant growth under varying environmental conditions (Choi et al., 2014).

Other names

SCF-MAX2SCF-D3SCF-ORE9SCF-Dwarf3SCF-MAX2 complexSkp1-Cullin-F-box MAX2 complex

Ligand-induced ubiquitination and proteasomal degradation of transcriptional repressors