Cell signaling regulates several physiological processes by receiving, processing, and transmitting signals between the extracellular and intracellular environments. In signal transduction, phosphorylation is a crucial effector as the most common posttranslational modification. Selectively recognizing specific phosphorylated motifs of target proteins and modulating their functions through binding interactions, the yeast 14-3-3 proteins Bmh1 and Bmh2 are involved in catabolite repression, carbon metabolism, endocytosis, and mitochondrial retrograde signaling, among other key cellular processes. These conserved scaffolding molecules also mediate crosstalk between ubiquitination and phosphorylation, the spatiotemporal control of meiosis, and the activity of ion transporters Trk1 and Nha1. In humans, deregulation of analogous processes triggers the development of serious diseases, such as diabetes, cancer, viral infections, microbial conditions and neuronal and age-related diseases. Accordingly, the aim of this review article is to provide a brief overview of the latest findings on the functions of yeast 14-3-3 proteins, focusing on their role in modulating the aforementioned processes.

• Keywords
• 14-3-3 proteins, adaptor protein, molecular mechanism, phosphorylation, protein-protein interaction, scaffolding, yeast,
• Publication type
• Journal Article MeSH
• Review MeSH

14-3-3 proteins are important dimeric scaffolds that regulate the function of hundreds of proteins in a phosphorylation-dependent manner. The SARS-CoV-2 nucleocapsid (N) protein forms a complex with human 14-3-3 proteins upon phosphorylation, which has also been described for other coronaviruses. Here, we report a high-resolution crystal structure of 14-3-3 bound to an N phosphopeptide bearing the phosphoserine 197 in the middle. The structure revealed two copies of the N phosphopeptide bound, each in the central binding groove of each 14-3-3 monomer. A complex network of hydrogen bonds and water bridges between the peptide and 14-3-3 was observed explaining the high affinity of the N protein for 14-3-3 proteins.

• MeSH
• COVID-19 MeSH
• Phosphopeptides chemistry   MeSH
• Phosphoproteins chemistry   MeSH
• Coronavirus Nucleocapsid Proteins * chemistry   MeSH
• Humans MeSH
• 14-3-3 Proteins * chemistry   MeSH
• SARS-CoV-2 * MeSH
• Protein Binding MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Phosphopeptides MeSH
• Phosphoproteins MeSH
• Coronavirus Nucleocapsid Proteins * MeSH
• nucleocapsid phosphoprotein, SARS-CoV-2 MeSH Browser
• 14-3-3 Proteins * MeSH

Phosphorylation by kinases governs many key cellular and extracellular processes, such as transcription, cell cycle progression, differentiation, secretion and apoptosis. Unsurprisingly, tight and precise kinase regulation is a prerequisite for normal cell functioning, whereas kinase dysregulation often leads to disease. Moreover, the functions of many kinases are regulated through protein-protein interactions, which in turn are mediated by phosphorylated motifs and often involve associations with the scaffolding and chaperon protein 14-3-3. Therefore, the aim of this review article is to provide an overview of the state of the art on 14-3-3-mediated kinase regulation, focusing on the most recent mechanistic insights into these important protein-protein interactions and discussing in detail both their structural aspects and functional consequences.

• Keywords
• 14-3-3, ASK1, CaMKK2, LRRK2, PI4KB, PKC, RAF kinase, kinase, phosphorylation,
• MeSH
• Allosteric Regulation genetics   MeSH
• Apoptosis genetics   MeSH
• Phosphorylation genetics   MeSH
• Humans MeSH
• p38 Mitogen-Activated Protein Kinases genetics   MeSH
• Protein Kinases genetics   MeSH
• 14-3-3 Proteins genetics   MeSH
• Signal Transduction genetics   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• p38 Mitogen-Activated Protein Kinases MeSH
• Protein Kinases MeSH
• 14-3-3 Proteins MeSH

Phosphatidylinositol 4-kinase IIIβ (PI4KB) is a key enzyme of the Golgi system because it produces its lipid hallmark - the phosphatidylinositol 4-phosphate (PI4P). It is recruited to Golgi by the Golgi resident ACBD3 protein, regulated by 14-3-3 proteins and it also serves as an adaptor because it recruits the small GTPase Rab11. Here, we analyzed the protein complexes formed by PI4KB in vitro using small angle x-ray scattering (SAXS) and we discovered that these protein complexes are highly flexible. The 14-3-3:PI4KB:Rab11 protein complex has 2:1:1 stoichiometry and its different conformations are rather compact, however, the ACBD3:PI4KB protein complex has both, very compact and very extended conformations. Furthermore, in vitro reconstitution revealed that the membrane is necessary for the formation of ACBD3:PI4KB:Rab11 protein complex at physiological (nanomolar) concentrations.

• MeSH
• Adaptor Proteins, Signal Transducing metabolism   MeSH
• Phosphotransferases (Alcohol Group Acceptor) metabolism   MeSH
• Intracellular Membranes metabolism   MeSH
• Scattering, Small Angle MeSH
• Membrane Proteins metabolism   MeSH
• Protein Multimerization * MeSH
• 14-3-3 Proteins metabolism   MeSH
• rab GTP-Binding Proteins metabolism   MeSH
• Recombinant Proteins metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• ACBD3 protein, human MeSH Browser
• Adaptor Proteins, Signal Transducing MeSH
• Phosphotransferases (Alcohol Group Acceptor) MeSH
• Membrane Proteins MeSH
• phosphatidylinositol 4-kinase IIIbeta, human MeSH Browser
• 14-3-3 Proteins MeSH
• rab GTP-Binding Proteins MeSH
• rab11 protein MeSH Browser
• Recombinant Proteins MeSH

Most single stranded plus RNA viruses hijack phosphatidylinositol 4-kinases (PI4Ks) to generate membranes highly enriched in phosphatidylinositol 4-phosphate (PI4P). These membranous compartments known as webs, replication factories or replication organelles are essential for viral replication because they provide protection from the innate intracellular immune response while serving as platforms for viral replication. Using purified recombinant proteins and biomimetic model membranes we show that the nonstructural viral 3A protein is sufficient to promote membrane hyper-phosphorylation given the proper intracellular cofactors (PI4KB and ACBD3). However, our bio-mimetic in vitro reconstitution assay revealed that rather than the presence of PI4P specifically, negative charge alone is sufficient for the recruitment of 3Dpol enzymes to the surface of the lipid bilayer. Additionally, we show that membrane tethered viral 3B protein (also known as Vpg) works in combination with the negative charge to increase the efficiency of membrane recruitment of 3Dpol.

• MeSH
• Adaptor Proteins, Signal Transducing genetics   metabolism   MeSH
• Cell Membrane metabolism   MeSH
• Phosphatidylinositol Phosphates metabolism   MeSH
• Phosphotransferases (Alcohol Group Acceptor) genetics   metabolism   MeSH
• Kobuvirus enzymology   MeSH
• Humans MeSH
• Membrane Proteins genetics   metabolism   MeSH
• Picornaviridae Infections metabolism   virology   MeSH
• Viral Nonstructural Proteins genetics   metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• ACBD3 protein, human MeSH Browser
• Adaptor Proteins, Signal Transducing MeSH
• Phosphatidylinositol Phosphates MeSH
• Phosphotransferases (Alcohol Group Acceptor) MeSH
• Membrane Proteins MeSH
• phosphatidylinositol 4-kinase IIIbeta, human MeSH Browser
• phosphatidylinositol 4-phosphate MeSH Browser
• Viral Nonstructural Proteins MeSH

The 14-3-3 proteins, a family of highly conserved scaffolding proteins ubiquitously expressed in all eukaryotic cells, interact with and regulate the function of several hundreds of partner proteins. Yeast neutral trehalases (Nth), enzymes responsible for the hydrolysis of trehalose to glucose, compared with trehalases from other organisms, possess distinct structure and regulation involving phosphorylation at multiple sites followed by binding to the 14-3-3 protein. Here we report the crystal structures of yeast Nth1 and its complex with Bmh1 (yeast 14-3-3 isoform), which, together with mutational and fluorescence studies, indicate that the binding of Nth1 by 14-3-3 triggers Nth1's activity by enabling the proper 3D configuration of Nth1's catalytic and calcium-binding domains relative to each other, thus stabilizing the flexible part of the active site required for catalysis. The presented structure of the Bmh1:Nth1 complex highlights the ability of 14-3-3 to modulate the structure of a multidomain binding partner and to function as an allosteric effector. Furthermore, comparison of the Bmh1:Nth1 complex structure with those of 14-3-3:serotonin N-acetyltransferase and 14-3-3:heat shock protein beta-6 complexes revealed similarities in the 3D structures of bound partner proteins, suggesting the highly conserved nature of 14-3-3 affects the structures of many client proteins.

• Keywords
• 14-3-3 protein, allostery, crystal structure, enzyme, trehalase,
• MeSH
• Arylalkylamine N-Acetyltransferase metabolism   MeSH
• Databases, Chemical * MeSH
• Phosphorylation MeSH
• Glucose metabolism   MeSH
• Catalytic Domain MeSH
• Protein Conformation MeSH
• Crystallography, X-Ray MeSH
• Models, Molecular MeSH
• Protein Domains MeSH
• 14-3-3 Proteins genetics   metabolism   MeSH
• Heat-Shock Proteins chemistry   metabolism   MeSH
• Saccharomyces cerevisiae Proteins chemistry   metabolism   MeSH
• Saccharomyces cerevisiae enzymology   genetics   metabolism   MeSH
• Trehalase chemistry   metabolism   MeSH
• Trehalose metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Arylalkylamine N-Acetyltransferase MeSH
• Glucose MeSH
• NTH1 protein, S cerevisiae MeSH Browser
• 14-3-3 Proteins MeSH
• Heat-Shock Proteins MeSH
• Saccharomyces cerevisiae Proteins MeSH
• Trehalase MeSH
• Trehalose MeSH