Structural basis for protein–protein interactions in the 14-3-3 protein family

Abstract

The seven members of the human 14-3-3 protein family regulate a diverse range of cell signaling pathways by formation of proteinprotein complexes with signaling proteins that contain phosphorylated Ser͞Thr residues within specific sequence motifs. Previously, crystal structures of three 14-3-3 isoforms (zeta, sigma, and tau) have been reported, with structural data for two isoforms deposited in the Protein Data Bank (zeta and sigma). In this study, we provide structural detail for five 14-3-3 isoforms bound to ligands, providing structural coverage for all isoforms of a human protein family. A comparative structural analysis of the seven 14-3-3 proteins revealed specificity determinants for binding of phosphopeptides in a specific orientation, target domain interaction surfaces and flexible adaptation of 14-3-3 proteins through domain movements. Specifically, the structures of the beta isoform in its apo and peptide bound forms showed that its binding site can exhibit structural flexibility to facilitate binding of its protein and peptide partners. In addition, the complex of 14-3-3 beta with the exoenzyme S peptide displayed a secondary structural element in the 14-3-3 peptide binding groove. These results show that the 14-3-3 proteins are adaptable structures in which internal flexibility is likely to facilitate recognition and binding of their interaction partners.phosphorylation ͉ signaling

Dysregulation of 14‐3‐3 proteins in neurodegenerative diseases with Lewy body or Alzheimer pathology

“…Of note, we observed insolubilization of several 14‐3‐3 isoforms while S232 phosphorylation is specific to 14‐3‐3 θ . As 14‐3‐3 θ can heterodimerize with other isoforms38, 39, 40, these findings suggest that increased S232 phosphorylation of 14‐3‐3 θ may be sufficient to drive insolubilization of other isoforms through heterodimerization.…”

De Novo Mutations in YWHAG Cause Early-Onset Epilepsy

“…Native 14-3-3 exists in monomeric and dimeric states as homo-and heterodimers, respectively, although 14-3-3g is almost entirely dimeric. 57 Glu15 is part of a triad of residues (Leu13, Ala14, and Glu15) necessary for 14-3-3g dimerization, 58,59 and its ability to complex with other proteins is potentially inhibited by substitution at this site.…”

“…57,60 An individual (ND27637) with Lennox-Gastaut syndrome and a de novo p.Asp129Glu variant is present in the Epi4K-EPGP dataset. 4 The Asp129 residue is also located within the 14-3-3g binding groove ( Figure 1) and plays an important role in determining the orientation of the phosphorylated peptides.…”

“…4 The Asp129 residue is also located within the 14-3-3g binding groove ( Figure 1) and plays an important role in determining the orientation of the phosphorylated peptides. 57 A de novo mutation affecting position p.Tyr133Ser has been reported in a Deciphering Developmental Disorders cohort individual (DDD4K.00159) severely affected by a neurodevelopmental disorder, 19 but we were unable to contact the clinician who followed this subject. Finally, a p.Lys50Gln de novo variant was identified in a subject with autism (AU027A).…”

Three-way Interaction between 14-3-3 Proteins, the N-terminal Region of Tyrosine Hydroxylase, and Negatively Charged Membranes

“…Phosphorylation at Ser 19 by either Ca 2ϩ / calmodulin-dependent kinase II, mitogen-activated protein kinase-activated protein kinase 2 (15,16), or p38-regulated/ activated kinase (17) promotes the high affinity binding to 14-3-3 proteins, which increases TH activity severalfold (17,18). TPH2 also binds to 14-3-3 proteins through phosphorylated Ser 19 (19), but little is known about the structural details of the interaction between TH (or TPH2) and 14-3-3, although crystal structures of all 14-3-3 isoforms with bound peptides or serotonin N-acetyltransferase have been determined (20,21). However, the structure of the regulatory N-terminal domain of TH and TPH2 has not been solved yet, and there is little sequence homology between the 14-3-3-interaction motifs in these hydroxylases and other partners.…”