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1.
Cell ; 185(2): 361-378.e25, 2022 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-34982960

RESUMO

Nuclear pore complexes (NPCs) mediate the nucleocytoplasmic transport of macromolecules. Here we provide a structure of the isolated yeast NPC in which the inner ring is resolved by cryo-EM at sub-nanometer resolution to show how flexible connectors tie together different structural and functional layers. These connectors may be targets for phosphorylation and regulated disassembly in cells with an open mitosis. Moreover, some nucleoporin pairs and transport factors have similar interaction motifs, which suggests an evolutionary and mechanistic link between assembly and transport. We provide evidence for three major NPC variants that may foreshadow functional specializations at the nuclear periphery. Cryo-electron tomography extended these studies, providing a model of the in situ NPC with a radially expanded inner ring. Our comprehensive model reveals features of the nuclear basket and central transporter, suggests a role for the lumenal Pom152 ring in restricting dilation, and highlights structural plasticity that may be required for transport.


Assuntos
Adaptação Fisiológica , Poro Nuclear/metabolismo , Saccharomyces cerevisiae/fisiologia , Motivos de Aminoácidos , Sequência de Aminoácidos , Fluorescência , Simulação de Acoplamento Molecular , Membrana Nuclear/metabolismo , Poro Nuclear/química , Complexo de Proteínas Formadoras de Poros Nucleares/química , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Domínios Proteicos , Reprodutibilidade dos Testes , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/metabolismo
2.
Cell ; 181(6): 1442-1442.e1, 2020 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-32531249

RESUMO

Meiosis is the specialized cell division that generates haploid gametes and is therefore essential for sexual reproduction. This SnapShot encompasses key events taking place during prophase I of meiosis that are required for achieving proper chromosome segregation and highlights how these are both conserved and diverged throughout five different species. To view this SnapShot, open or download the PDF.


Assuntos
Meiose/fisiologia , Prófase Meiótica I/fisiologia , Animais , Arabidopsis/fisiologia , Caenorhabditis elegans/fisiologia , Segregação de Cromossomos/fisiologia , Drosophila melanogaster/fisiologia , Camundongos , Saccharomyces cerevisiae/fisiologia
3.
Cell ; 169(1): 24-34, 2017 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-28340346

RESUMO

Interconnectivity and feedback control are hallmarks of biological systems. This includes communication between organelles, which allows them to function and adapt to changing cellular environments. While the specific mechanisms for all communications remain opaque, unraveling the wiring of organelle networks is critical to understand how biological systems are built and why they might collapse, as occurs in aging. A comprehensive understanding of all the routes involved in inter-organelle communication is still lacking, but important themes are beginning to emerge, primarily in budding yeast. These routes are reviewed here in the context of sub-system proteostasis and complex adaptive systems theory.


Assuntos
Organelas/fisiologia , Saccharomyces cerevisiae/citologia , Envelhecimento/fisiologia , Animais , Divisão Celular , Humanos , Proteínas/química , Saccharomyces cerevisiae/fisiologia , Transdução de Sinais
4.
Cell ; 171(4): 890-903.e18, 2017 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-29107329

RESUMO

Eukaryotic cells have evolved extensive protein quality-control mechanisms to remove faulty translation products. Here, we show that yeast cells continually produce faulty mitochondrial polypeptides that stall on the ribosome during translation but are imported into the mitochondria. The cytosolic protein Vms1, together with the E3 ligase Ltn1, protects against the mitochondrial toxicity of these proteins and maintains cell viability under respiratory conditions. In the absence of these factors, stalled polypeptides aggregate after import and sequester critical mitochondrial chaperone and translation machinery. Aggregation depends on C-terminal alanyl/threonyl sequences (CAT-tails) that are attached to stalled polypeptides on 60S ribosomes by Rqc2. Vms1 binds to 60S ribosomes at the mitochondrial surface and antagonizes Rqc2, thereby facilitating import, impeding aggregation, and directing aberrant polypeptides to intra-mitochondrial quality control. Vms1 is a key component of a rescue pathway for ribosome-stalled mitochondrial polypeptides that are inaccessible to ubiquitylation due to coupling of translation and translocation.


Assuntos
Proteínas de Transporte/metabolismo , Mitocôndrias/fisiologia , Ribossomos/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/citologia , Citosol/metabolismo , Transporte de Elétrons , Homeostase , Saccharomyces cerevisiae/fisiologia , Ubiquitina-Proteína Ligases/metabolismo
5.
Cell ; 168(6): 1028-1040.e19, 2017 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-28283059

RESUMO

In eukaryotic cells, diverse stresses trigger coalescence of RNA-binding proteins into stress granules. In vitro, stress-granule-associated proteins can demix to form liquids, hydrogels, and other assemblies lacking fixed stoichiometry. Observing these phenomena has generally required conditions far removed from physiological stresses. We show that poly(A)-binding protein (Pab1 in yeast), a defining marker of stress granules, phase separates and forms hydrogels in vitro upon exposure to physiological stress conditions. Other RNA-binding proteins depend upon low-complexity regions (LCRs) or RNA for phase separation, whereas Pab1's LCR is not required for demixing, and RNA inhibits it. Based on unique evolutionary patterns, we create LCR mutations, which systematically tune its biophysical properties and Pab1 phase separation in vitro and in vivo. Mutations that impede phase separation reduce organism fitness during prolonged stress. Poly(A)-binding protein thus acts as a physiological stress sensor, exploiting phase separation to precisely mark stress onset, a broadly generalizable mechanism.


Assuntos
Grânulos Citoplasmáticos/metabolismo , Proteínas de Ligação a Poli(A)/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/fisiologia , Sequência de Aminoácidos , Grânulos Citoplasmáticos/química , Temperatura Alta , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Proteínas Intrinsicamente Desordenadas/química , Proteínas Intrinsicamente Desordenadas/metabolismo , Mutagênese , Proteínas de Ligação a Poli(A)/química , Proteínas de Ligação a Poli(A)/genética , Prolina/análise , Prolina/metabolismo , Domínios Proteicos , Ribonucleases/metabolismo , Saccharomyces cerevisiae/crescimento & desenvolvimento , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Alinhamento de Sequência , Estresse Fisiológico
6.
Cell ; 166(6): 1397-1410.e16, 2016 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-27610566

RESUMO

Whereas domestication of livestock, pets, and crops is well documented, it is still unclear to what extent microbes associated with the production of food have also undergone human selection and where the plethora of industrial strains originates from. Here, we present the genomes and phenomes of 157 industrial Saccharomyces cerevisiae yeasts. Our analyses reveal that today's industrial yeasts can be divided into five sublineages that are genetically and phenotypically separated from wild strains and originate from only a few ancestors through complex patterns of domestication and local divergence. Large-scale phenotyping and genome analysis further show strong industry-specific selection for stress tolerance, sugar utilization, and flavor production, while the sexual cycle and other phenotypes related to survival in nature show decay, particularly in beer yeasts. Together, these results shed light on the origins, evolutionary history, and phenotypic diversity of industrial yeasts and provide a resource for further selection of superior strains. PAPERCLIP.


Assuntos
Cerveja/microbiologia , Microbiologia Industrial , Filogenia , Saccharomyces cerevisiae/classificação , Saccharomyces cerevisiae/fisiologia , Variações do Número de Cópias de DNA/genética , Genes Fúngicos/genética , Variação Genética , Genoma Fúngico/genética , Viabilidade Microbiana/genética , Fenótipo , Ploidias , Saccharomyces cerevisiae/genética , Seleção Genética
7.
Cell ; 163(3): 549-59, 2015 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-26496602

RESUMO

Adaptation is the process in which organisms improve their fitness by changing their phenotype using genetic or non-genetic mechanisms. The adaptation toolbox consists of varied molecular and genetic means that we posit span an almost continuous "adaptation spectrum." Different adaptations are characterized by the time needed for organisms to attain them and by their duration. We suggest that organisms often adapt by progressing the adaptation spectrum, starting with rapidly attained physiological and epigenetic adaptations and culminating with slower long-lasting genetic ones. A tantalizing possibility is that earlier adaptations facilitate realization of later ones.


Assuntos
Adaptação Fisiológica , Evolução Biológica , Mutação , Animais , Metilação de DNA , Epigênese Genética , Humanos , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/genética , Plasmodium falciparum/fisiologia , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/fisiologia
8.
Cell ; 162(6): 1286-98, 2015 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-26359986

RESUMO

Heat causes protein misfolding and aggregation and, in eukaryotic cells, triggers aggregation of proteins and RNA into stress granules. We have carried out extensive proteomic studies to quantify heat-triggered aggregation and subsequent disaggregation in budding yeast, identifying >170 endogenous proteins aggregating within minutes of heat shock in multiple subcellular compartments. We demonstrate that these aggregated proteins are not misfolded and destined for degradation. Stable-isotope labeling reveals that even severely aggregated endogenous proteins are disaggregated without degradation during recovery from shock, contrasting with the rapid degradation observed for many exogenous thermolabile proteins. Although aggregation likely inactivates many cellular proteins, in the case of a heterotrimeric aminoacyl-tRNA synthetase complex, the aggregated proteins remain active with unaltered fidelity. We propose that most heat-induced aggregation of mature proteins reflects the operation of an adaptive, autoregulatory process of functionally significant aggregate assembly and disassembly that aids cellular adaptation to thermal stress.


Assuntos
Resposta ao Choque Térmico , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/fisiologia , Cicloeximida/farmacologia , Grânulos Citoplasmáticos/metabolismo , Agregados Proteicos , Biossíntese de Proteínas/efeitos dos fármacos , Inibidores da Síntese de Proteínas/farmacologia , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/metabolismo
9.
Cell ; 160(6): 1182-95, 2015 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-25768911

RESUMO

Cells make accurate decisions in the face of molecular noise and environmental fluctuations by relying not only on present pathway activity, but also on their memory of past signaling dynamics. Once a decision is made, cellular transitions are often rapid and switch-like due to positive feedback loops in the regulatory network. While positive feedback loops are good at promoting switch-like transitions, they are not expected to retain information to inform subsequent decisions. However, this expectation is based on our current understanding of network motifs that accounts for temporal, but not spatial, dynamics. Here, we show how spatial organization of the feedback-driven yeast G1/S switch enables the transmission of memory of past pheromone exposure across this transition. We expect this to be one of many examples where the exquisite spatial organization of the eukaryotic cell enables previously well-characterized network motifs to perform new and unexpected signal processing functions.


Assuntos
Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/fisiologia , Proteínas de Ciclo Celular/metabolismo , Proteínas Inibidoras de Quinase Dependente de Ciclina/metabolismo , Ciclinas/metabolismo , Citoplasma/metabolismo , Retroalimentação Fisiológica , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Feromônios/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Transdução de Sinais
10.
Cell ; 157(6): 1473-1487, 2014 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-24906158

RESUMO

Endocytosis is critical for cellular physiology and thus is highly regulated. To identify regulatory interactions controlling the endocytic membrane system, we conducted 13 RNAi screens on multiple endocytic activities and their downstream organelles. Combined with image analysis of thousands of single cells per perturbation and their cell-to-cell variability, this created a high-quality and cross-comparable quantitative data set. Unbiased analysis revealed emergent properties of the endocytic membrane system and how its complexity evolved and distinct programs of regulatory control that coregulate specific subsets of endocytic uptake routes and organelle abundances. We show that these subset effects allow the mapping of functional regulatory interactions and their interaction motifs between kinases, membrane-trafficking machinery, and the cytoskeleton at a large scale, some of which we further characterize. Our work presents a powerful approach to identify regulatory interactions in complex cellular systems from parallel single-gene or double-gene perturbation screens in human cells and yeast.


Assuntos
Técnicas Citológicas , Endocitose , Regulação da Expressão Gênica , Técnicas Genéticas , Saccharomyces cerevisiae/citologia , Animais , Endossomos/fisiologia , Técnicas de Inativação de Genes , Complexo de Golgi/fisiologia , Humanos , Lisossomos/fisiologia , Filogenia , Interferência de RNA , Saccharomyces cerevisiae/fisiologia
11.
Cell ; 159(3): 530-42, 2014 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-25417105

RESUMO

Aggregation of damaged or misfolded proteins is a protective mechanism against proteotoxic stress, abnormalities of which underlie many aging-related diseases. Here, we show that in asymmetrically dividing yeast cells, aggregation of cytosolic misfolded proteins does not occur spontaneously but requires new polypeptide synthesis and is restricted to the surface of ER, which harbors the majority of active translation sites. Protein aggregates formed on ER are frequently also associated with or are later captured by mitochondria, greatly constraining aggregate mobility. During mitosis, aggregates are tethered to well-anchored maternal mitochondria, whereas mitochondria acquired by the bud are largely free of aggregates. Disruption of aggregate-mitochondria association resulted in increased mobility and leakage of mother-accumulated aggregates into the bud. Cells with advanced replicative age exhibit gradual decline of aggregates-mitochondria association, likely contributing to their diminished ability to rejuvenate through asymmetric cell division.


Assuntos
Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/fisiologia , Divisão Celular , Citosol/metabolismo , Retículo Endoplasmático/metabolismo , Mitocôndrias/metabolismo , Agregados Proteicos , Biossíntese de Proteínas , Saccharomyces cerevisiae/crescimento & desenvolvimento , Estresse Fisiológico
12.
Annu Rev Cell Dev Biol ; 31: 55-81, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26443192

RESUMO

Organelle inheritance is a process whereby organelles are actively distributed between dividing cells at cytokinesis. Much valuable insight into the molecular mechanisms of organelle inheritance has come from the analysis of asymmetrically dividing cells, which transport a portion of their organelles to the bud while retaining another portion in the mother cell. Common principles apply to the inheritance of all organelles, although individual organelles use specific factors for their partitioning. Inheritance factors can be classified as motors, which are required for organelle transport; anchors, which immobilize organelles at distinct cell structures; or connectors, which mediate the attachment of organelles to motors and anchors. Here, we provide an overview of recent advances in the field of organelle inheritance and highlight how motor, anchor, and connector molecules choreograph the segregation of a multicopy organelle, the peroxisome. We also discuss the role of organelle population control in the generation of cellular diversity.


Assuntos
Transporte Biológico/fisiologia , Divisão Celular/fisiologia , Organelas/fisiologia , Animais , Citocinese/fisiologia , Humanos , Proteínas de Membrana , Peroxissomos/fisiologia , Saccharomyces cerevisiae/fisiologia
13.
Cell ; 154(5): 983-995, 2013 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-23993092

RESUMO

DNA damage triggers polyubiquitylation and degradation of the largest subunit of RNA polymerase II (RNAPII), a "mechanism of last resort" employed during transcription stress. In yeast, this process is dependent on Def1 through a previously unresolved mechanism. Here, we report that Def1 becomes activated through ubiquitylation- and proteasome-dependent processing. Def1 processing results in the removal of a domain promoting cytoplasmic localization, resulting in nuclear accumulation of the clipped protein. Nuclear Def1 then binds RNAPII, utilizing a ubiquitin-binding domain to recruit the Elongin-Cullin E3 ligase complex via a ubiquitin-homology domain in the Ela1 protein. This facilitates polyubiquitylation of Rpb1, triggering its proteasome-mediated degradation. Together, these results outline the multistep mechanism of Rpb1 polyubiquitylation triggered by transcription stress and uncover the key role played by Def1 as a facilitator of Elongin-Cullin ubiquitin ligase function.


Assuntos
Proteínas Cromossômicas não Histona/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/fisiologia , Transcrição Gênica , Sequência de Aminoácidos , Proteínas Cromossômicas não Histona/química , Dados de Sequência Molecular , Complexo de Endopeptidases do Proteassoma/metabolismo , Estrutura Terciária de Proteína , RNA Polimerase II/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Alinhamento de Sequência , Estresse Fisiológico , Complexos Ubiquitina-Proteína Ligase/metabolismo
14.
Mol Cell ; 77(2): 266-278.e6, 2020 01 16.
Artigo em Inglês | MEDLINE | ID: mdl-31757756

RESUMO

Theory and experiments suggest that organisms would benefit from pre-adaptation to future stressors based on reproducible environmental fluctuations experienced by their ancestors, but the mechanisms driving pre-adaptation remain enigmatic. We report that the [SMAUG+] prion allows yeast to anticipate nutrient repletion after periods of starvation, providing a strong selective advantage. By transforming the landscape of post-transcriptional gene expression, [SMAUG+] regulates the decision between two broad growth and survival strategies: mitotic proliferation or meiotic differentiation into a stress-resistant state. [SMAUG+] is common in laboratory yeast strains, where standard propagation practice produces regular cycles of nutrient scarcity followed by repletion. Distinct [SMAUG+] variants are also widespread in wild yeast isolates from multiple niches, establishing that prion polymorphs can be utilized in natural populations. Our data provide a striking example of how protein-based epigenetic switches, hidden in plain sight, can establish a transgenerational memory that integrates adaptive prediction into developmental decisions.


Assuntos
Diferenciação Celular/fisiologia , Príons/metabolismo , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/fisiologia , Adaptação Fisiológica/fisiologia , Proliferação de Células/fisiologia , Proteínas de Saccharomyces cerevisiae/metabolismo
15.
Cell ; 150(1): 151-64, 2012 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-22727045

RESUMO

Cellular wound healing, enabling the repair of membrane damage, is ubiquitous in eukaryotes. One aspect of the wound healing response is the redirection of a polarized cytoskeleton and the secretory machinery to the damage site. Although there has been recent progress in identifying conserved proteins involved in wound healing, the mechanisms linking these components into a coherent response are not defined. Using laser damage in budding yeast, we demonstrate that local cell wall/membrane damage triggers the dispersal of proteins from the site of polarized growth, enabling their accumulation at the wound. We define a protein-kinase-C-dependent mechanism that mediates the destruction of the formin Bni1 and the exocyst component Sec3. This degradation is essential to prevent competition between the site of polarized growth and the wound. Mechanisms to overcome competition from a pre-existing polarized cytoskeleton may be a general feature of effective wound healing in polarized cells.


Assuntos
Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/fisiologia , Polaridade Celular , Citoesqueleto/metabolismo , Eucariotos/citologia , Eucariotos/fisiologia , Proteínas dos Microfilamentos/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo
16.
Cell ; 150(6): 1170-81, 2012 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-22959267

RESUMO

The cell-fate decision leading to gametogenesis is essential for sexual reproduction. In S. cerevisiae, only diploid MATa/α but not haploid MATa or MATα cells undergo gametogenesis, known as sporulation. We find that transcription of two long noncoding RNAs (lncRNAs) mediates mating-type control of sporulation. In MATa or MATα haploids, expression of IME1, the central inducer of gametogenesis, is inhibited in cis by transcription of the lncRNA IRT1, located in the IME1 promoter. IRT1 transcription recruits the Set2 histone methyltransferase and the Set3 histone deacetylase complex to establish repressive chromatin at the IME1 promoter. Inhibiting expression of IRT1 and an antisense transcript that antagonizes the expression of the meiotic regulator IME4 allows cells expressing the haploid mating type to sporulate with kinetics that are indistinguishable from that of MATa/α diploids. Conversely, expression of the two lncRNAs abolishes sporulation in MATa/α diploids. Thus, transcription of two lncRNAs governs mating-type control of gametogenesis in yeast.


Assuntos
Regulação Fúngica da Expressão Gênica , Genes Fúngicos Tipo Acasalamento , RNA Fúngico/genética , RNA Longo não Codificante/genética , Saccharomyces cerevisiae/genética , Transcrição Gênica , Gametogênese , Proteínas Nucleares/genética , Regiões Promotoras Genéticas , Proteínas Repressoras/metabolismo , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/fisiologia , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Esporos Fúngicos , Fatores de Transcrição/genética
17.
EMBO J ; 41(4): e109446, 2022 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-35023198

RESUMO

Sexual reproduction requires genome haploidization by the two divisions of meiosis and a differentiation program to generate gametes. Here, we have investigated how sporulation, the yeast equivalent of gamete differentiation, is coordinated with progression through meiosis. Spore differentiation is initiated at metaphase II when a membrane-nucleating structure, called the meiotic plaque, is assembled at the centrosome. While all components of this structure accumulate already at entry into meiosis I, they cannot assemble because centrosomes are occupied by Spc72, the receptor of the γ-tubulin complex. Spc72 is removed from centrosomes by a pathway that depends on the polo-like kinase Cdc5 and the meiosis-specific kinase Ime2, which is unleashed by the degradation of Spo13/Meikin upon activation of the anaphase-promoting complex at anaphase I. Meiotic plaques are finally assembled upon reactivation of Cdk1 at entry into metaphase II. This unblocking-activation mechanism ensures that only single-copy genomes are packaged into spores and might serve as a paradigm for the regulation of other meiosis II-specific processes.


Assuntos
Meiose , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/fisiologia , Esporos Fúngicos/fisiologia , Proteínas Cdc20/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Ciclina B/metabolismo , Proteínas de Ligação a DNA/metabolismo , Cinetocoros/metabolismo , Meiose/fisiologia , Metáfase/fisiologia , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Saccharomyces cerevisiae/citologia , Proteínas de Saccharomyces cerevisiae/genética , Esporos Fúngicos/citologia , Fatores de Transcrição/metabolismo
18.
Cell ; 147(5): 1104-17, 2011 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-22118465

RESUMO

The TORC1 kinase signaling complex is a key determinant of cell growth that senses nutritional status and responds by coordinating diverse cellular processes including transcription, translation, and autophagy. Here, we demonstrate that TORC1 modulates the composition of plasma membrane (PM) proteins by regulating ubiquitin-mediated endocytosis. The mechanism involves the Npr1 kinase, a negative regulator of endocytosis that is itself negatively regulated by TORC1. We show that Npr1 inhibits the activity of Art1, an arrestin-like adaptor protein that promotes endocytosis by targeting the Rsp5 ubiquitin ligase to specific PM cargoes. Npr1 antagonizes Art1-mediated endocytosis via N-terminal phosphorylation, a modification that prevents Art1 association with the PM. Thus, our study adds ubiquitin ligase targeting and control of endocytosis to the known effector mechanisms of TORC1, underscoring how TORC1 coordinates ubiquitin-mediated endocytosis with protein synthesis and autophagy in order to regulate cell growth.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas Quinases/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/fisiologia , Fatores de Transcrição/metabolismo , Sistemas de Transporte de Aminoácidos/metabolismo , Aminoácidos/metabolismo , Membrana Celular/metabolismo , Endocitose , Fosforilação , Estresse Fisiológico , Ubiquitina-Proteína Ligases/metabolismo
19.
Cell ; 147(2): 320-31, 2011 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-22000012

RESUMO

In budding yeast, the most abundantly spliced pre-mRNAs encode ribosomal proteins (RPs). To investigate the contribution of splicing to ribosome production and function, we systematically eliminated introns from all RP genes to evaluate their impact on RNA expression, pre-rRNA processing, cell growth, and response to stress. The majority of introns were required for optimal cell fitness or growth under stress. Most introns are found in duplicated RP genes, and surprisingly, in the majority of cases, deleting the intron from one gene copy affected the expression of the other in a nonreciprocal manner. Consistently, 70% of all duplicated genes were asymmetrically expressed, and both introns and gene deletions displayed copy-specific phenotypic effects. Together, our results indicate that splicing in yeast RP genes mediates intergene regulation and implicate the expression ratio of duplicated RP genes in modulating ribosome function.


Assuntos
Íntrons , Proteínas Ribossômicas/genética , Ribossomos/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/fisiologia , Duplicação Gênica , Regulação Fúngica da Expressão Gênica , Viabilidade Microbiana , Biossíntese de Proteínas , Proteínas Ribossômicas/metabolismo , Saccharomyces cerevisiae/citologia , Proteínas de Saccharomyces cerevisiae/metabolismo , Estresse Fisiológico
20.
Cell ; 146(6): 969-79, 2011 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-21906795

RESUMO

Acetylation of histone and nonhistone proteins is an important posttranslational modification affecting many cellular processes. Here, we report that NuA4 acetylation of Sip2, a regulatory ß subunit of the Snf1 complex (yeast AMP-activated protein kinase), decreases as cells age. Sip2 acetylation, controlled by antagonizing NuA4 acetyltransferase and Rpd3 deacetylase, enhances interaction with Snf1, the catalytic subunit of Snf1 complex. Sip2-Snf1 interaction inhibits Snf1 activity, thus decreasing phosphorylation of a downstream target, Sch9 (homolog of Akt/S6K), and ultimately leading to slower growth but extended replicative life span. Sip2 acetylation mimetics are more resistant to oxidative stress. We further demonstrate that the anti-aging effect of Sip2 acetylation is independent of extrinsic nutrient availability and TORC1 activity. We propose a protein acetylation-phosphorylation cascade that regulates Sch9 activity, controls intrinsic aging, and extends replicative life span in yeast.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/fisiologia , Transativadores/metabolismo , Acetilação , Restrição Calórica , Divisão Celular , Histona Acetiltransferases/metabolismo , Histona Desacetilases/metabolismo , Proteínas Quinases/metabolismo , Saccharomyces cerevisiae/enzimologia , Fatores de Transcrição/metabolismo
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