B4 Raf-like MAPKKK RAF24 regulates Arabidopsis thaliana flowering time

ABSTRACT: The timing of flowering is a critical agronomic trait governed by a number of different internal and external events, such as temperature, light and photoperiod. Despite a firm understanding of flowering time from a genetic standpoint, there exists a limited understanding of how post-translational modifications may influence flowering, and what molecular PTM machinery is responsible for catalyzing these events. Here, we identify and characterize a novel B4 Raf-like MAPKKK protein kinase called RAF24, which exhibits an early flowering phenotype. Analysis of closely-related B4 Raf-like MAPKKK protein kinases RAF18 and RAF20, indicate that RAF24 is the only B4 RAF to possess an early flowering phenotype. Through quantitative proteomics, we then found that RAF24 impacts the phosphorylation status of numerous flowering related proteins related to the autonomous flowering pathway, with changes in the phosphorylation status of HISTONE MONO-UBIQUITINATION 2 (HUB2) representing the largest fold-change. Subsequent analysis of the HUB2 protein interactome by quantitative affinity purification mass spectrometry (AP-MS) revealed a relationship between HUB2 phosphorylation at S314 phosphorylation status and HUB2 function that manifest as changes in activity and protein-protein interactions. Use of phospho-memetic and -ablative mutants validate the importance of S314, directly linking this HUB2 phosphorylation event to the proper control of flowering time. Collectively, our findings implicate RAF24 as a higher-order regulator of flowering, while further implicating HUB2 as a centerpiece of flowering time regulation in plants.

INSTRUMENT(S): Orbitrap Fusion Lumos, Orbitrap Fusion

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

TISSUE(S): Plant Cell, Leaf

SUBMITTER: Richard Uhrig  

LAB HEAD: Richard Glen Uhrig

PROVIDER: PXD038688 | Pride | 2025-05-09

REPOSITORIES: Pride