RESUMO
Here, we report the design, construction, and characterization of a tRNA neochromosome, a designer chromosome that functions as an additional, de novo counterpart to the native complement of Saccharomyces cerevisiae. Intending to address one of the central design principles of the Sc2.0 project, the â¼190-kb tRNA neochromosome houses all 275 relocated nuclear tRNA genes. To maximize stability, the design incorporates orthogonal genetic elements from non-S. cerevisiae yeast species. Furthermore, the presence of 283 rox recombination sites enables an orthogonal tRNA SCRaMbLE system. Following construction in yeast, we obtained evidence of a potent selective force, manifesting as a spontaneous doubling in cell ploidy. Furthermore, tRNA sequencing, transcriptomics, proteomics, nucleosome mapping, replication profiling, FISH, and Hi-C were undertaken to investigate questions of tRNA neochromosome behavior and function. Its construction demonstrates the remarkable tractability of the yeast model and opens up opportunities to directly test hypotheses surrounding these essential non-coding RNAs.
Assuntos
Cromossomos Artificiais de Levedura , Genoma Fúngico , Saccharomyces cerevisiae , Perfilação da Expressão Gênica , Proteômica , Saccharomyces cerevisiae/genética , Biologia Sintética , RNA de Transferência/genética , Cromossomos Artificiais de Levedura/genéticaRESUMO
Brown adipose tissue (BAT) regulates metabolic physiology. However, nearly all mechanistic studies of BAT protein function occur in a single inbred mouse strain, which has limited the understanding of generalizable mechanisms of BAT regulation over physiology. Here, we perform deep quantitative proteomics of BAT across a cohort of 163 genetically defined diversity outbred mice, a model that parallels the genetic and phenotypic variation found in humans. We leverage this diversity to define the functional architecture of the outbred BAT proteome, comprising 10,479 proteins. We assign co-operative functions to 2,578 proteins, enabling systematic discovery of regulators of BAT. We also identify 638 proteins that correlate with protection from, or sensitivity to, at least one parameter of metabolic disease. We use these findings to uncover SFXN5, LETMD1, and ATP1A2 as modulators of BAT thermogenesis or adiposity, and provide OPABAT as a resource for understanding the conserved mechanisms of BAT regulation over metabolic physiology.
Assuntos
Tecido Adiposo Marrom , Proteoma , Humanos , Camundongos , Animais , Tecido Adiposo Marrom/metabolismo , Proteoma/metabolismo , Termogênese/fisiologia , Adiposidade , Obesidade/metabolismo , Camundongos Endogâmicos C57BL , Proteínas Proto-Oncogênicas/metabolismoRESUMO
Yeast ataxin-2, also known as Pbp1, senses the activity state of mitochondria in order to regulate TORC1. A domain of Pbp1 required to adapt cells to mitochondrial activity is of low sequence complexity. The low-complexity (LC) domain of Pbp1 forms labile, cross-ß polymers that facilitate phase transition of the protein into liquid-like or gel-like states. Phase transition for other LC domains is reliant upon widely distributed aromatic amino acids. In place of tyrosine or phenylalanine residues prototypically used for phase separation, Pbp1 contains 24 similarly disposed methionine residues. Here, we show that the Pbp1 methionine residues are sensitive to hydrogen peroxide (H2O2)-mediated oxidation in vitro and in living cells. Methionine oxidation melts Pbp1 liquid-like droplets in a manner reversed by methionine sulfoxide reductase enzymes. These observations explain how reversible formation of labile polymers by the Pbp1 LC domain enables the protein to function as a sensor of cellular redox state.
Assuntos
Proteínas de Transporte/metabolismo , Metionina/química , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Sequência de Aminoácidos , Proteínas de Transporte/química , Proteínas de Transporte/genética , Peróxido de Hidrogênio/farmacologia , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Metionina/metabolismo , Metionina Sulfóxido Redutases/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mutagênese Sítio-Dirigida , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Transição de Fase , Domínios Proteicos , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genéticaRESUMO
Yeast ataxin-2, also known as Pbp1 (polyA binding protein-binding protein 1), is an intrinsically disordered protein implicated in stress granule formation, RNA biology, and neurodegenerative disease. To understand the endogenous function of this protein, we identify Pbp1 as a dedicated regulator of TORC1 signaling and autophagy under conditions that require mitochondrial respiration. Pbp1 binds to TORC1 specifically during respiratory growth, but utilizes an additional methionine-rich, low complexity (LC) region to inhibit TORC1. This LC region causes phase separation, forms reversible fibrils, and enables self-association into assemblies required for TORC1 inhibition. Mutants that weaken phase separation in vitro exhibit reduced capacity to inhibit TORC1 and induce autophagy. Loss of Pbp1 leads to mitochondrial dysfunction and reduced fitness during nutritional stress. Thus, Pbp1 forms a condensate in response to respiratory status to regulate TORC1 signaling.
Assuntos
Proteínas de Transporte/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Transdução de Sinais , Sequência de Aminoácidos , Autofagia/efeitos dos fármacos , Proteínas de Transporte/química , Proteínas de Transporte/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/antagonistas & inibidores , Metionina/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mutagênese Sítio-Dirigida , Fosforilação , Ligação Proteica , Domínios Proteicos , Saccharomyces cerevisiae/crescimento & desenvolvimento , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Transdução de Sinais/efeitos dos fármacos , Sirolimo/farmacologiaRESUMO
Acetyl-CoA represents a central node of carbon metabolism that plays a key role in bioenergetics, cell proliferation, and the regulation of gene expression. Highly glycolytic or hypoxic tumors must produce sufficient quantities of this metabolite to support cell growth and survival under nutrient-limiting conditions. Here, we show that the nucleocytosolic acetyl-CoA synthetase enzyme, ACSS2, supplies a key source of acetyl-CoA for tumors by capturing acetate as a carbon source. Despite exhibiting no gross deficits in growth or development, adult mice lacking ACSS2 exhibit a significant reduction in tumor burden in two different models of hepatocellular carcinoma. ACSS2 is expressed in a large proportion of human tumors, and its activity is responsible for the majority of cellular acetate uptake into both lipids and histones. These observations may qualify ACSS2 as a targetable metabolic vulnerability of a wide spectrum of tumors.
Assuntos
Acetato-CoA Ligase/metabolismo , Acetatos/metabolismo , Neoplasias/metabolismo , Acetato-CoA Ligase/análise , Acetato-CoA Ligase/genética , Acetilcoenzima A/metabolismo , Animais , Humanos , Imuno-Histoquímica , Neoplasias Hepáticas/metabolismo , Camundongos , Neoplasias/química , Neoplasias/patologia , Tomografia por Emissão de Pósitrons , Neoplasias de Mama Triplo Negativas/química , Neoplasias de Mama Triplo Negativas/patologiaRESUMO
Pain information processing in the spinal cord has been postulated to rely on nociceptive transmission (T) neurons receiving inputs from nociceptors and Aß mechanoreceptors, with Aß inputs gated through feed-forward activation of spinal inhibitory neurons (INs). Here, we used intersectional genetic manipulations to identify these critical components of pain transduction. Marking and ablating six populations of spinal excitatory and inhibitory neurons, coupled with behavioral and electrophysiological analysis, showed that excitatory neurons expressing somatostatin (SOM) include T-type cells, whose ablation causes loss of mechanical pain. Inhibitory neurons marked by the expression of dynorphin (Dyn) represent INs, which are necessary to gate Aß fibers from activating SOM(+) neurons to evoke pain. Therefore, peripheral mechanical nociceptors and Aß mechanoreceptors, together with spinal SOM(+) excitatory and Dyn(+) inhibitory neurons, form a microcircuit that transmits and gates mechanical pain. PAPERCLIP:
Assuntos
Neurônios/fisiologia , Dor/metabolismo , Medula Espinal/fisiologia , Animais , Dinorfinas/metabolismo , Mecanorreceptores/metabolismo , Camundongos , Percepção da Dor , Somatostatina/metabolismoRESUMO
Lactate is abundant in rapidly dividing cells owing to the requirement for elevated glucose catabolism to support proliferation1-6. However, it is not known whether accumulated lactate affects the proliferative state. Here we use a systematic approach to determine lactate-dependent regulation of proteins across the human proteome. From these data, we identify a mechanism of cell cycle regulation whereby accumulated lactate remodels the anaphase promoting complex (APC/C). Remodelling of APC/C in this way is caused by direct inhibition of the SUMO protease SENP1 by lactate. We find that accumulated lactate binds and inhibits SENP1 by forming a complex with zinc in the SENP1 active site. SENP1 inhibition by lactate stabilizes SUMOylation of two residues on APC4, which drives UBE2C binding to APC/C. This direct regulation of APC/C by lactate stimulates timed degradation of cell cycle proteins, and efficient mitotic exit in proliferative human cells. This mechanism is initiated upon mitotic entry when lactate abundance reaches its apex. In this way, accumulation of lactate communicates the consequences of a nutrient-replete growth phase to stimulate timed opening of APC/C, cell division and proliferation. Conversely, persistent accumulation of lactate drives aberrant APC/C remodelling and can overcome anti-mitotic pharmacology via mitotic slippage. In sum, we define a biochemical mechanism through which lactate directly regulates protein function to control the cell cycle and proliferation.
Assuntos
Ciclossomo-Complexo Promotor de Anáfase , Proteínas de Ciclo Celular , Ciclo Celular , Ácido Láctico , Humanos , Anáfase , Ciclossomo-Complexo Promotor de Anáfase/metabolismo , Proteínas de Ciclo Celular/metabolismo , Ácido Láctico/metabolismo , MitoseRESUMO
Nuclear export of unspliced and singly spliced viral mRNA is a critical step in the HIV life cycle. The structural basis by which the virus selects its own mRNA among more abundant host cellular RNAs for export has been a mystery for more than 25 years. Here, we describe an unusual topological structure that the virus uses to recognize its own mRNA. The viral Rev response element (RRE) adopts an "A"-like structure in which the two legs constitute two tracks of binding sites for the viral Rev protein and position the two primary known Rev-binding sites ~55 Å apart, matching the distance between the two RNA-binding motifs in the Rev dimer. Both the legs of the "A" and the separation between them are required for optimal RRE function. This structure accounts for the specificity of Rev for the RRE and thus the specific recognition of the viral RNA.
Assuntos
Transporte Ativo do Núcleo Celular , HIV-1/química , RNA Mensageiro/química , RNA Viral/química , Produtos do Gene rev do Vírus da Imunodeficiência Humana/química , Sequência de Bases , Sítios de Ligação , Núcleo Celular/metabolismo , Células HEK293 , HIV-1/genética , Humanos , Dados de Sequência Molecular , Poro Nuclear/metabolismo , Conformação de Ácido Nucleico , Dobramento de RNA , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Viral/genética , RNA Viral/metabolismo , Espalhamento a Baixo Ângulo , Difração de Raios X , Produtos do Gene rev do Vírus da Imunodeficiência Humana/genética , Produtos do Gene rev do Vírus da Imunodeficiência Humana/metabolismoRESUMO
An essential step toward understanding brain function is to establish a structural framework with cellular resolution on which multi-scale datasets spanning molecules, cells, circuits and systems can be integrated and interpreted1. Here, as part of the collaborative Brain Initiative Cell Census Network (BICCN), we derive a comprehensive cell type-based anatomical description of one exemplar brain structure, the mouse primary motor cortex, upper limb area (MOp-ul). Using genetic and viral labelling, barcoded anatomy resolved by sequencing, single-neuron reconstruction, whole-brain imaging and cloud-based neuroinformatics tools, we delineated the MOp-ul in 3D and refined its sublaminar organization. We defined around two dozen projection neuron types in the MOp-ul and derived an input-output wiring diagram, which will facilitate future analyses of motor control circuitry across molecular, cellular and system levels. This work provides a roadmap towards a comprehensive cellular-resolution description of mammalian brain architecture.
Assuntos
Córtex Motor/anatomia & histologia , Córtex Motor/citologia , Neurônios/classificação , Animais , Atlas como Assunto , Feminino , Neurônios GABAérgicos/citologia , Neurônios GABAérgicos/metabolismo , Glutamatos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neuroimagem , Neurônios/citologia , Neurônios/metabolismo , Especificidade de Órgãos , Análise de Sequência de RNA , Análise de Célula ÚnicaRESUMO
Dysregulation of chromatin methylation is associated with defects in cellular differentiation as well as a variety of cancers. How cells regulate the opposing activities of histone methyltransferase and demethylase enzymes to set the methylation status of the epigenome for proper control of gene expression and metabolism remains poorly understood. Here, we show that loss of methylation of the major phosphatase PP2A in response to methionine starvation activates the demethylation of histones through hyperphosphorylation of specific demethylase enzymes. In parallel, this regulatory mechanism enables cells to preserve SAM by increasing SAH to limit SAM consumption by methyltransferase enzymes. Mutants lacking the PP2A methyltransferase or the effector H3K36 demethylase Rph1 exhibit elevated SAM levels and are dependent on cysteine due to reduced capacity to sink the methyl groups of SAM. Therefore, PP2A directs the methylation status of histones by regulating the phosphorylation status of histone demethylase enzymes in response to SAM levels.
Assuntos
Cromatina/metabolismo , Metilação de DNA , Histonas/metabolismo , Proteína Fosfatase 2/metabolismo , Processamento de Proteína Pós-Traducional , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/enzimologia , Cromatina/genética , Remoção de Radical Alquila , Regulação Fúngica da Expressão Gênica , Histona Desmetilases/genética , Histona Desmetilases/metabolismo , Metilação , Mutação , Ligação Proteica , Proteína Fosfatase 2/genética , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , S-Adenosilmetionina/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genéticaRESUMO
Rapid accumulation of repair factors at DNA double-strand breaks (DSBs) is essential for DSB repair. Several factors involved in DSB repair have been found undergoing liquid-liquid phase separation (LLPS) at DSB sites to facilitate DNA repair. RNF168, a RING-type E3 ubiquitin ligase, catalyzes H2A.X ubiquitination for recruiting DNA repair factors. Yet, whether RNF168 undergoes LLPS at DSB sites remains unclear. Here, we identified K63-linked polyubiquitin-triggered RNF168 condensation which further promoted RNF168-mediated DSB repair. RNF168 formed liquid-like condensates upon irradiation in the nucleus while purified RNF168 protein also condensed in vitro. An intrinsically disordered region containing amino acids 460-550 was identified as the essential domain for RNF168 condensation. Interestingly, LLPS of RNF168 was significantly enhanced by K63-linked polyubiquitin chains, and LLPS largely enhanced the RNF168-mediated H2A.X ubiquitination, suggesting a positive feedback loop to facilitate RNF168 rapid accumulation and its catalytic activity. Functionally, LLPS deficiency of RNF168 resulted in delayed recruitment of 53BP1 and BRCA1 and subsequent impairment in DSB repair. Taken together, our finding demonstrates the pivotal effect of LLPS in RNF168-mediated DSB repair.
Assuntos
Reparo do DNA , Ubiquitina-Proteína Ligases , Humanos , Quebras de DNA de Cadeia Dupla , Histonas/metabolismo , Histonas/genética , Poliubiquitina/metabolismo , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/metabolismo , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/genética , Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitina-Proteína Ligases/genética , UbiquitinaçãoRESUMO
As the Coronavirus Disease 2019 (COVID-19) pandemic continues, there is a growing concern regarding the relationship between viral infections and neuropathic pain. Chronic neuropathic pain resulting from virus-induced neural dysfunction has emerged as a significant issue currently faced. However, the molecular mechanisms underlying this phenomenon remain unclear, and clinical treatment outcomes are often suboptimal. Therefore, delving into the relationship between viral infections and neuropathic pain, exploring the pathophysiological characteristics and molecular mechanisms of different viral pain models, can contribute to the discovery of potential therapeutic targets and methods, thereby enhancing pain relief and improving the quality of life for patients. This review focuses on HIV-related neuropathic pain (HNP), postherpetic neuralgia (PHN), and neuropathic pain caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections, examining rodent models and relevant cellular molecular pathways. Through elucidating the connection between viral infections and neuropathic pain, it aims to delineate the current limitations and challenges faced by treatments, thereby providing insights and directions for future clinical practice and research.
Assuntos
COVID-19 , Neuralgia , SARS-CoV-2 , Humanos , Neuralgia/virologia , Neuralgia/terapia , Neuralgia/etiologia , Animais , COVID-19/complicações , COVID-19/virologia , COVID-19/terapia , Infecções por HIV/complicações , Infecções por HIV/virologia , Infecções por HIV/tratamento farmacológico , Neuralgia Pós-Herpética/virologia , Neuralgia Pós-Herpética/terapiaRESUMO
Mutations in mitochondrial DNA (mtDNA) contribute to a variety of serious multi-organ human diseases, which are strictly inherited from the maternal germline. However, there is currently no curative treatment. Attention has been focused on preventing the transmission of mitochondrial diseases through mitochondrial replacement (MR) therapy, but levels of mutant mtDNA can often unexpectedly undergo significant changes known as mitochondrial genetic drift. Here, we proposed a novel strategy to perform spindle-chromosomal complex transfer (SCCT) with maximal residue removal (MRR) in metaphase II (MII) oocytes, thus hopefully eliminated the transmission of mtDNA diseases. With the MRR procedure, we initially investigated the proportions of mtDNA copy numbers in isolated karyoplasts to those of individual oocytes. Spindle-chromosomal morphology and copy number variation (CNV) analysis also confirmed the safety of this method. Then, we reconstructed oocytes by MRR-SCCT, which well developed to blastocysts with minimal mtDNA residue and normal chromosomal copy numbers. Meanwhile, we optimized the manipulation order between intracytoplasmic sperm injection (ICSI) and SCC transfer and concluded that ICSI-then-transfer was conducive to avoid premature activation of reconstructed oocytes in favor of normal fertilization. Offspring of mice generated by embryos transplantation in vivo and embryonic stem cells derivation further presented evidences for competitive development competence and stable mtDNA carryover without genetic drift. Importantly, we also successfully accomplished SCCT in human MII oocytes resulting in tiny mtDNA residue and excellent embryo development through MRR manipulation. Taken together, our preclinical mouse and human models of the MRR-SCCT strategy not only demonstrated efficient residue removal but also high compatibility with normal embryo development, thus could potentially be served as a feasible clinical treatment to prevent the transmission of inherited mtDNA diseases.
Assuntos
Variações do Número de Cópias de DNA , Doenças Mitocondriais , Masculino , Humanos , Animais , Camundongos , Variações do Número de Cópias de DNA/genética , Sêmen , Mitocôndrias/genética , DNA Mitocondrial/genética , DNA Mitocondrial/análise , Doenças Mitocondriais/genética , Doenças Mitocondriais/prevenção & controle , OócitosRESUMO
Motile bacteria navigate toward favorable conditions and away from unfavorable environments using chemotaxis. Mechanisms of sensing attractants are well understood; however, molecular aspects of how bacteria sense repellents have not been established. Here, we identified malate as a repellent recognized by the MCP2201 chemoreceptor in a bacterium Comamonas testosteroni and showed that it binds to the same site as an attractant citrate. Binding determinants for a repellent and an attractant had only minor differences, and a single amino acid substitution in the binding site inverted the response to malate from a repellent to an attractant. We found that malate and citrate affect the oligomerization state of the ligand-binding domain in opposing way. We also observed opposing effects of repellent and attractant binding on the orientation of an alpha helix connecting the sensory domain to the transmembrane helix. We propose a model to illustrate how positive and negative signals might be generated.
Assuntos
Proteínas de Bactérias , Malatos , Proteínas Quimiotáticas Aceptoras de Metil/química , Proteínas de Bactérias/metabolismo , Ligantes , Escherichia coli/metabolismo , Quimiotaxia/fisiologia , Bactérias/metabolismo , CitratosRESUMO
BACKGROUND: Cardiac hypertrophy and its associated remodeling are among the leading causes of heart failure. Lysine crotonylation is a recently discovered posttranslational modification whose role in cardiac hypertrophy remains largely unknown. NAE1 (NEDD8 [neural precursor cell expressed developmentally downregulated protein 8]-activating enzyme E1 regulatory subunit) is mainly involved in the neddylation modification of protein targets. However, the function of crotonylated NAE1 has not been defined. This study aims to elucidate the effects and mechanisms of NAE1 crotonylation on cardiac hypertrophy. METHODS: Crotonylation levels were detected in both human and mouse subjects with cardiac hypertrophy through immunoprecipitation and Western blot assays. Tandem mass tag (TMT)-labeled quantitative lysine crotonylome analysis was performed to identify the crotonylated proteins in a mouse cardiac hypertrophic model induced by transverse aortic constriction. We generated NAE1 knock-in mice carrying a crotonylation-defective K238R (lysine to arginine mutation at site 238) mutation (NAE1 K238R) and NAE1 knock-in mice expressing a crotonylation-mimicking K238Q (lysine to glutamine mutation at site 238) mutation (NAE1 K238Q) to assess the functional role of crotonylation of NAE1 at K238 in pathological cardiac hypertrophy. Furthermore, we combined coimmunoprecipitation, mass spectrometry, and dot blot analysis that was followed by multiple molecular biological methodologies to identify the target GSN (gelsolin) and corresponding molecular events contributing to the function of NAE1 K238 (lysine residue at site 238) crotonylation. RESULTS: The crotonylation level of NAE1 was increased in mice and patients with cardiac hypertrophy. Quantitative crotonylomics analysis revealed that K238 was the main crotonylation site of NAE1. Loss of K238 crotonylation in NAE1 K238R knock-in mice attenuated cardiac hypertrophy and restored the heart function, while hypercrotonylation mimic in NAE1 K238Q knock-in mice significantly enhanced transverse aortic constriction-induced pathological hypertrophic response, leading to impaired cardiac structure and function. The recombinant adenoviral vector carrying NAE1 K238R mutant attenuated, while the K238Q mutant aggravated Ang II (angiotensin II)-induced hypertrophy. Mechanistically, we identified GSN as a direct target of NAE1. K238 crotonylation of NAE1 promoted GSN neddylation and, thus, enhanced its protein stability and expression. NAE1 crotonylation-dependent increase of GSN promoted actin-severing activity, which resulted in adverse cytoskeletal remodeling and progression of pathological hypertrophy. CONCLUSIONS: Our findings provide new insights into the previously unrecognized role of crotonylation on nonhistone proteins during cardiac hypertrophy. We found that K238 crotonylation of NAE1 plays an essential role in mediating cardiac hypertrophy through GSN neddylation, which provides potential novel therapeutic targets for pathological hypertrophy and cardiac remodeling.
Assuntos
Cardiomegalia , Animais , Humanos , Cardiomegalia/metabolismo , Cardiomegalia/patologia , Cardiomegalia/genética , Camundongos , Masculino , Processamento de Proteína Pós-Traducional , Camundongos Endogâmicos C57BL , Enzimas Ativadoras de Ubiquitina/metabolismo , Enzimas Ativadoras de Ubiquitina/genética , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Camundongos Transgênicos , Proteína NEDD8/metabolismo , Proteína NEDD8/genética , Células HEK293RESUMO
At a synapse, fast synchronous neurotransmitter release requires localization of Ca(2+) channels to presynaptic active zones. How Ca(2+) channels are recruited to active zones, however, remains unknown. Using unbiased yeast two-hybrid screens, we here identify a direct interaction of the central PDZ domain of the active-zone protein RIM with the C termini of presynaptic N- and P/Q-type Ca(2+) channels but not L-type Ca(2+) channels. To test the physiological significance of this interaction, we generated conditional knockout mice lacking all multidomain RIM isoforms. Deletion of RIM proteins ablated most neurotransmitter release by simultaneously impairing the priming of synaptic vesicles and by decreasing the presynaptic localization of Ca(2+) channels. Strikingly, rescue of the decreased Ca(2+)-channel localization required the RIM PDZ domain, whereas rescue of vesicle priming required the RIM N terminus. We propose that RIMs tether N- and P/Q-type Ca(2+) channels to presynaptic active zones via a direct PDZ-domain-mediated interaction, thereby enabling fast, synchronous triggering of neurotransmitter release at a synapse.
Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Canais de Cálcio/metabolismo , Proteínas de Ligação ao GTP/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Transportadores de Cassetes de Ligação de ATP/química , Animais , Cálcio/metabolismo , Canais de Cálcio/química , Proteínas de Ligação ao GTP/química , Camundongos , Camundongos Knockout , Proteínas do Tecido Nervoso/química , Neurotransmissores/metabolismo , Terminações Pré-Sinápticas/metabolismo , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Estrutura Terciária de Proteína , Técnicas do Sistema de Duplo-HíbridoRESUMO
Bulk amorphous materials have been studied extensively and are widely used, yet their atomic arrangement remains an open issue. Although they are generally believed to be Zachariasen continuous random networks1, recent experimental evidence favours the competing crystallite model in the case of amorphous silicon2-4. In two-dimensional materials, however, the corresponding questions remain unanswered. Here we report the synthesis, by laser-assisted chemical vapour deposition5, of centimetre-scale, free-standing, continuous and stable monolayer amorphous carbon, topologically distinct from disordered graphene. Unlike in bulk materials, the structure of monolayer amorphous carbon can be determined by atomic-resolution imaging. Extensive characterization by Raman and X-ray spectroscopy and transmission electron microscopy reveals the complete absence of long-range periodicity and a threefold-coordinated structure with a wide distribution of bond lengths, bond angles, and five-, six-, seven- and eight-member rings. The ring distribution is not a Zachariasen continuous random network, but resembles the competing (nano)crystallite model6. We construct a corresponding model that enables density-functional-theory calculations of the properties of monolayer amorphous carbon, in accordance with observations. Direct measurements confirm that it is insulating, with resistivity values similar to those of boron nitride grown by chemical vapour deposition. Free-standing monolayer amorphous carbon is surprisingly stable and deforms to a high breaking strength, without crack propagation from the point of fracture. The excellent physical properties of this stable, free-standing monolayer amorphous carbon could prove useful for permeation and diffusion barriers in applications such as magnetic recording devices and flexible electronics.
RESUMO
Ubiquitin-specific proteases (USPs) are a family of multi-domain deubiquitinases (DUBs) with variable architectures, some containing regulatory auxiliary domains. Among the USP family, all occurrences of intramolecular regulation presently known are autoactivating. USP8 remains the sole exception as its putative WW-like domain, conserved only in vertebrate orthologs, is autoinhibitory. Here, we present a comprehensive structure-function analysis describing the autoinhibition of USP8 and provide evidence of the physical interaction between the WW-like and catalytic domains. The solution structure of full-length USP8 reveals an extended, monomeric conformation. Coupled with DUB assays, the WW-like domain is confirmed to be the minimal autoinhibitory unit. Strikingly, autoinhibition is only observed with the WW-like domain in cis and depends on the length of the linker tethering it to the catalytic domain. Modeling of the WW:CD complex structure and mutagenesis of interface residues suggests a novel binding site in the S1 pocket. To investigate the interplay between phosphorylation and USP8 autoinhibition, we identify AMP-activated protein kinase as a highly selective modifier of S718 in the 14-3-3 binding motif. We show that 14-3-3γ binding to phosphorylated USP8 potentiates autoinhibition in a WW-like domain-dependent manner by stabilizing an autoinhibited conformation. These findings provide mechanistic details on the autoregulation of USP8 and shed light on its evolutionary significance.
Assuntos
Ubiquitina Tiolesterase , Humanos , Ubiquitina Tiolesterase/metabolismo , Ubiquitina Tiolesterase/química , Ubiquitina Tiolesterase/genética , Fosforilação , Domínio Catalítico , Endopeptidases/metabolismo , Endopeptidases/química , Endopeptidases/genética , Domínios Proteicos , Modelos Moleculares , Proteínas 14-3-3/metabolismo , Proteínas 14-3-3/química , Proteínas 14-3-3/genética , Complexos Endossomais de Distribuição Requeridos para TransporteRESUMO
Drought stress is one of the dominating challenges to the growth and productivity in crop plants. Elucidating the molecular mechanisms of plants responses to drought stress is fundamental to improve fruit quality. However, such molecular mechanisms are poorly understood in apple (Malus domestica Borkh.). In this study, we explored that the BTB-BACK-TAZ protein, MdBT2, negatively modulates the drought tolerance of apple plantlets. Moreover, we identified a novel Homeodomain-leucine zipper (HD-Zip) transcription factor, MdHDZ27, using a yeast two-hybrid (Y2H) screen with MdBT2 as the bait. Overexpression of MdHDZ27 in apple plantlets, calli, and tomato plantlets enhanced their drought tolerance by promoting the expression of drought tolerance-related genes [responsive to dehydration 29A (MdRD29A) and MdRD29B]. Biochemical analyses demonstrated that MdHDZ27 directly binds to and activates the promoters of MdRD29A and MdRD29B. Furthermore, in vitro and in vivo assays indicate that MdBT2 interacts with and ubiquitinates MdHDZ27, via the ubiquitin/26S proteasome pathway. This ubiquitination results in the degradation of MdHDZ27 and weakens the transcriptional activation of MdHDZ27 on MdRD29A and MdRD29B. Finally, a series of transgenic analyses in apple plantlets further clarified the role of the relationship between MdBT2 and MdHDZ27, as well as the effect of their interaction on drought resistance in apple plantlets. Collectively, our findings reveal a novel mechanism by which the MdBT2-MdHDZ27 regulatory module controls drought tolerance, which is of great significance for enhancing the drought resistance of apple and other plants.
Assuntos
Resistência à Seca , Malus , Proteínas de Plantas , Fatores de Transcrição , Ubiquitinação , Resistência à Seca/genética , Regulação da Expressão Gênica de Plantas , Malus/genética , Malus/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Estresse Fisiológico , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Epilepsy is a chronic neurological disorder featuring recurrent, unprovoked seizures, which affect more than 65 million people worldwide. Here, we discover that the PKHD1L1, which is encoded by polycystic kidney and hepatic disease1-like 1 (Pkhd1l1), wildly distributes in neurons in the central nervous system (CNS) of mice. Disruption of PKHD1L1 in the dentate gyrus region of the hippocampus leads to increased susceptibility to pentylenetetrazol-induced seizures in mice. The disturbance of PKHD1L1 leads to the overactivation of the mitogen-activated protein kinase (MAPK)/extracellular regulated kinase (ERK)-Calpain pathway, which is accompanied by remarkable degradation of cytoplasmic potassium chloride co-transporter 2 (KCC2) level together with the impaired expression and function of membrane KCC2. However, the reduction of membrane KCC2 is associated with the damaged inhibitory ability of the vital GABA receptors, which ultimately leads to the significantly increased susceptibility to epileptic seizures. Our data, thus, indicate for the first time that Pkhd1l1, a newly discovered polycystic kidney disease (PKD) association gene, is required in neurons to maintain neuronal excitability by regulation of KCC2 expression in CNS. A new mechanism of the clinical association between genetic PKD and seizures has been built, which could be a potential therapeutic target for treating PKD-related seizures.