Hierarchized phosphotarget binding by the seven human 14-3-3 isoforms

Gergo Gogl,Nikolai N Sluchanko,Pascal Eberling,Kristina V Tugaeva,Camille Kostmann,Gilles Trave

doi:10.1038/s41467-021-21908-8

Abstract

The seven 14-3-3 isoforms are highly abundant human proteins encoded by similar yet distinct genes. 14-3-3 proteins recognize phosphorylated motifs within numerous human and viral proteins. Here, we analyze by X-ray crystallography, fluorescence polarization, mutagenesis and fusicoccin-mediated modulation the structural basis and druggability of 14-3-3 binding to four E6 oncoproteins of tumorigenic human papillomaviruses. 14-3-3 isoforms bind variant and mutated phospho-motifs of E6 and unrelated protein RSK1 with different affinities, albeit following an ordered affinity ranking with conserved relative KD ratios. Remarkably, 14-3-3 isoforms obey the same hierarchy when binding to most of their established targets, as supported by literature and a recent human complexome map. This knowledge allows predicting proportions of 14-3-3 isoforms engaged with phosphoproteins in various tissues. Notwithstanding their individual functions, cellular concentrations of 14-3-3 may be collectively adjusted to buffer the strongest phosphorylation outbursts, explaining their expression variations in different tissues and tumors.

Highlights

The seven [-3] isoforms are highly abundant human proteins encoded by similar yet distinct genes. 14-3-3 proteins recognize phosphorylated motifs within numerous human and viral proteins
We show that the seven [-3] isoforms bound phospho-PDZ domain-binding motif (PBM) of E6 proteins and of the unrelated human RSK kinase with different affinities, albeit obeying a hierarchized profile with conserved relative KD ratios
Among all 225 HPV E6 proteins curated in the PaVE database, 31 E6 proteins from mucosal α-genera HPV possess a C-terminal PBM with the class 1 consensus (X(S/T)X(L/V/I/C)-COOH, where X is any amino acid residue30,31)

Summary

Introduction

The seven [-3] isoforms are highly abundant human proteins encoded by similar yet distinct genes. 14-3-3 proteins recognize phosphorylated motifs within numerous human and viral proteins. The seven [-3] isoforms are highly abundant human proteins encoded by similar yet distinct genes. 143-3 isoforms obey the same hierarchy when binding to most of their established targets, as supported by literature and a recent human complexome map. This knowledge allows predicting proportions of [-3] isoforms engaged with phosphoproteins in various tissues. The seven human [-3] isoforms, individually named β, γ, ε, ζ, η, σ, and τ (beta, gamma, epsilon, zeta, eta, sigma, and tau)[1], are distinct gene encoded paralogs that are highly similar in sequence and in their phosphopeptiderecognition mode, yet display different expression patterns across tissues.

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Results

Conclusion