Biochemical signatures strongly demarcate phylogenetic groups of plant 14‐3‐3 isoforms

• DOI: 10.1111/tpj.70017
• Publication Date: 2025-03-12T05:51:39Z
• Authors: Ilya A. Sedlov; Nikolai N. Sluchanko

Interaction of dimeric 14-3-3 proteins with phosphotargets regulates various physiological processes in plants, from flowering to transpiration and salt tolerance. Several genes express distinct "isoforms," particularly numerous but these are unevenly studied even model species. Here we systematically investigated twelve isoforms Arabidopsis thaliana. While all can homodimerize, four representing a supposedly more ancestral, epsilon phylogenetic group (iota, mu, omicron, epsilon), not their eight non-epsilon counterparts (omega, phi, chi, psi, upsilon, nu, kappa, lambda), exhibit concentration-dependent monomerization, pronounced surface hydrophobicity at physiologically relevant protein concentrations under crowding conditions typical for the cell. We show that dramatically lowered thermodynamic stabilities entail aggregation near-physiological temperatures accelerate proteolytic degradation vitro plant cell lysates. Mutations iota, inspired by structural analysis, helped us rescue behavior pinpoint key positions responsible epsilon/non-epsilon demarcation. Combining two major demarcating (namely, 27th 51st omega) differences biochemical properties, developed an demarcation criterion classified 89% available sequences Dicots, Monocots, Gymnosperms, Ferns, Lycophytes 99.7% accuracy, reliably predicted properties given isoform, which experimentally verified distant Selaginella moellendorffii. The proven occurrence both groups primitive plants refines traditional phylogenetic, solely sequence-based analysis provides intriguing insights into evolutionary history group.