Flexibility of intrinsically disordered degrons in AUX/IAA proteins reinforces auxin co-receptor assemblies.

ABSTRACT: Cullin RING-type E3 ubiquitin ligases SCF^TIR1/AFB1-5 and their AUX/IAA targets perceive the phytohormone auxin. The F-box protein TIR1 binds a surface-exposed degron in AUX/IAAs promoting their ubiquitylation and rapid auxin-regulated proteasomal degradation. Here, by adopting biochemical, structural proteomics and in vivo approaches we unveil how flexibility in AUX/IAAs and regions in TIR1 affect their conformational ensemble allowing surface accessibility of degrons. We resolve TIR1·auxin·IAA7 and TIR1·auxin·IAA12 complex topology, and show that flexible intrinsically disordered regions (IDRs) in the degron's vicinity, cooperatively position AUX/IAAs on TIR1. We identify essential residues at the TIR1 N- and C-termini, which provide non-native interaction interfaces with IDRs

SUBMITTER: Niemeyer M 

PROVIDER: S-EPMC7210949 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature