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1.
Nat Commun ; 12(1): 6064, 2021 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-34663815

RESUMO

Calcineurin, the conserved protein phosphatase and target of immunosuppressants, is a critical mediator of Ca2+ signaling. Here, to discover calcineurin-regulated processes we examined an understudied isoform, CNAß1. We show that unlike canonical cytosolic calcineurin, CNAß1 localizes to the plasma membrane and Golgi due to palmitoylation of its divergent C-terminal tail, which is reversed by the ABHD17A depalmitoylase. Palmitoylation targets CNAß1 to a distinct set of membrane-associated interactors including the phosphatidylinositol 4-kinase (PI4KA) complex containing EFR3B, PI4KA, TTC7B and FAM126A. Hydrogen-deuterium exchange reveals multiple calcineurin-PI4KA complex contacts, including a calcineurin-binding peptide motif in the disordered tail of FAM126A, which we establish as a calcineurin substrate. Calcineurin inhibitors decrease PI4P production during Gq-coupled GPCR signaling, suggesting that calcineurin dephosphorylates and promotes PI4KA complex activity. In sum, this work discovers a calcineurin-regulated signaling pathway which highlights the PI4KA complex as a regulatory target and reveals that dynamic palmitoylation confers unique localization, substrate specificity and regulation to CNAß1.


Assuntos
1-Fosfatidilinositol 4-Quinase/metabolismo , Membrana Celular/metabolismo , Lipoilação/fisiologia , Monoéster Fosfórico Hidrolases/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Calcineurina/metabolismo , Linhagem Celular , Citoplasma/metabolismo , Complexo de Golgi/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/química , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Ligação Proteica , Isoformas de Proteínas/metabolismo , Transdução de Sinais/fisiologia
2.
J Mol Biol ; 433(18): 167145, 2021 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-34229011

RESUMO

Transport Protein Particle complexes (TRAPP) are evolutionarily conserved regulators of membrane trafficking, with this mediated by their guanine nucleotide exchange factor (GEF) activity towards Rab GTPases. In metazoans evidence suggests that two different TRAPP complexes exist, TRAPPII and TRAPPIII. These two complexes share a common core of subunits, with complex specific subunits (TRAPPC9 and TRAPPC10 in TRAPPII and TRAPPC8, TRAPPC11, TRAPPC12, TRAPPC13 in TRAPPIII). TRAPPII and TRAPPIII have distinct specificity for GEF activity towards Rabs, with TRAPPIII acting on Rab1, and TRAPPII acting on Rab1 and Rab11. The molecular basis for how these complex specific subunits alter GEF activity towards Rab GTPases is unknown. Here we have used a combination of biochemical assays, hydrogen deuterium exchange mass spectrometry (HDX-MS) and electron microscopy to examine the regulation of TRAPPII and TRAPPIIII complexes in solution and on membranes. GEF assays revealed that TRAPPIII has GEF activity against Rab1 and Rab43, with no detectable activity against the other 18 Rabs tested. The TRAPPIII complex had significant differences in protein dynamics at the Rab binding site compared to TRAPPII, potentially indicating an important role of accessory subunits in altering the active site of TRAPP complexes. Both the TRAPPII and TRAPPIII complexes had enhanced GEF activity on lipid membranes, with HDX-MS revealing numerous conformational changes that accompany membrane association. HDX-MS also identified a membrane binding site in TRAPPC8. Collectively, our results provide insight into the functions of TRAPP complexes and how they can achieve Rab specificity.


Assuntos
Membrana Celular/metabolismo , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Mamíferos/metabolismo , Proteínas de Transporte Vesicular/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Animais , Sítios de Ligação , Fatores de Troca do Nucleotídeo Guanina/genética , Humanos , Mamíferos/genética , Conformação Proteica , Transporte Proteico , Proteínas de Transporte Vesicular/química , Proteínas de Transporte Vesicular/genética , Proteínas rab de Ligação ao GTP/genética
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