RESUMO
The dimorphic yeast Yarrowia lipolytica possesses an excellent ability to utilize n-alkane as a sole carbon and energy source. Although there are detailed studies on the enzymes that catalyze the reactions in the metabolic processes of n-alkane in Y. lipolytica, the molecular mechanism underlying the incorporation of n-alkane into the cells remains to be elucidated. Because Y. lipolytica adsorbs n-alkane, we postulated that Y. lipolytica incorporates n-alkane through direct interaction with it. We isolated and characterized mutants defective in adsorption to n-hexadecane. One of the mutants harbored a nonsense mutation in MAR1 (Morphology and n-alkane Adsorption Regulator 1) encoding a protein containing a high mobility group box. The deletion mutant of MAR1 exhibited defects in adsorption to n-hexadecane and filamentous growth on solid media, whereas the strain that overexpressed MAR1 exhibited hyperfilamentous growth. Fluorescence microscopic observations suggested that Mar1 localizes in the nucleus. RNA-sequencing analysis revealed the alteration of the transcript levels of several genes, including those encoding transcription factors and cell surface proteins, by the deletion of MAR1. These findings suggest that MAR1 is involved in the transcriptional regulation of the genes required for n-alkane adsorption and cell morphology transition.IMPORTANCEYarrowia lipolytica, a dimorphic yeast capable of assimilating n-alkane as a carbon and energy source, has been extensively studied as a promising host for bioconversion of n-alkane into useful chemicals and bioremediation of soil and water contaminated by petroleum. While the metabolic pathway of n-alkane in this yeast and the enzymes involved in this pathway have been well characterized, the molecular mechanism to incorporate n-alkane into the cells is yet to be fully understood. Due to the ability of Y. lipolytica to adsorb n-alkane, it has been hypothesized that Y. lipolytica incorporates n-alkane through direct interaction with it. In this study, we identified a gene, MAR1, which plays a crucial role in the transcriptional regulation of the genes necessary for the adsorption to n-alkane and the transition of the cell morphology in Y. lipolytica. Our findings provide valuable insights that could lead to advanced applications of Y. lipolytica in n-alkane bioconversion and bioremediation.
Assuntos
Alcanos , Proteínas Fúngicas , Yarrowia , Yarrowia/genética , Yarrowia/metabolismo , Yarrowia/crescimento & desenvolvimento , Alcanos/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Adsorção , Regulação Fúngica da Expressão GênicaRESUMO
BACKGROUND: Human prion diseases (HPDs) are fatal neurodegenerative disorders characterized by abnormal prion proteins (PrPSc). However, the detection of prion seeding activity in patients with high sensitivity remains challenging. Even though real-time quaking-induced conversion (RT-QuIC) assay is suitable for detecting prion seeding activity in a variety of specimens, it shows lower accuracy when whole blood, blood plasma, and blood-contaminated tissue samples are used. In this study, we developed a novel technology for the in vitro amplification of abnormal prion proteins in HPD to the end of enabling their detection with high sensitivity known as the enhanced quaking-induced conversion (eQuIC) assay. METHODS: Three antibodies were used to develop the novel eQUIC method. Thereafter, SD50 seed activity was analyzed using brain tissue samples from patients with prion disease using the conventional RT-QUIC assay and the novel eQUIC assay. In addition, blood samples from six patients with solitary prion disease were analyzed using the novel eQuIC assay. RESULTS: The eQuIC assay, involving the use of three types of human monoclonal antibodies, showed approximately 1000-fold higher sensitivity than the original RT-QuIC assay. However, when this assay was used to analyze blood samples from six patients with sporadic human prion disease, no prion activity was detected. CONCLUSION: The detection of prion seeding activity in blood samples from patients with sporadic prion disease remains challenging. Thus, the development of alternative methods other than RT-QuIC and eQuIC will be necessary for future research.
Assuntos
Síndrome de Creutzfeldt-Jakob , Doenças Priônicas , Príons , Humanos , Príons/metabolismo , Proteínas Priônicas , Doenças Priônicas/diagnóstico , Doenças Priônicas/metabolismo , Encéfalo/metabolismo , Plasma/metabolismo , Síndrome de Creutzfeldt-Jakob/diagnósticoRESUMO
In fungi, the cell wall plays a crucial role in morphogenesis and response to stress from the external environment. Chitin is one of the main cell wall components in many filamentous fungi. In Aspergillus nidulans, a class III chitin synthase ChsB plays a pivotal role in hyphal extension and morphogenesis. However, little is known about post-translational modifications of ChsB and their functional impacts. In this study, we showed that ChsB is phosphorylated in vivo. We characterized strains that produce ChsB using stepwise truncations of its N-terminal disordered region or deletions of some residues in that region and demonstrated its involvement in ChsB abundance on the hyphal apical surface and in hyphal tip localization. Furthermore, we showed that some deletions in this region affected the phosphorylation states of ChsB, raising the possibility that these states are important for the localization of ChsB to the hyphal surface and the growth of A. nidulans. Our findings indicate that ChsB transport is regulated by its N-terminal disordered region.
Assuntos
Aspergillus nidulans , Aspergillus nidulans/genética , Hifas , Parede Celular/metabolismo , Quitina Sintase/genética , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismoRESUMO
Although a 74-year-old man with gastric cancer with pyloric stenosis(cT4aN[+]M0, Stage â ¢)had undergone surgery, he was diagnosed with peritoneum dissemination. He received bypass surgery, and an intraperitoneal access port was implanted in his subcutaneous space. Postoperatively, he received 4 courses of SOX therapy. In treatment effect, the primary tumor showed no change, and ascites developed. Therefore, we changed the chemotherapy regimen in intravenous and intraperitoneal paclitaxel combined with S-1 therapy. After starting this regimen, the primary tumor decreased in size, and the pyloric stenosis improved. Currently, the patient is alive without recurrence for 5 years and 8 months after intravenous and intraperitoneal paclitaxel combined with S-1 therapy and receiving this treatment regularly.
Assuntos
Neoplasias Peritoneais , Estenose Pilórica , Neoplasias Gástricas , Masculino , Humanos , Idoso , Paclitaxel , Neoplasias Gástricas/tratamento farmacológico , Neoplasias Gástricas/cirurgia , Neoplasias Gástricas/patologia , Peritônio/patologia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Peritoneais/tratamento farmacológico , Neoplasias Peritoneais/cirurgia , Estenose Pilórica/etiologia , Estenose Pilórica/cirurgiaRESUMO
The cellular prion protein, PrPC, is a glycosylphosphatidylinositol anchored-membrane glycoprotein expressed most abundantly in neuronal and to a lesser extent in non-neuronal cells. Its conformational conversion into the amyloidogenic isoform in neurons is a key pathogenic event in prion diseases, including Creutzfeldt-Jakob disease in humans and scrapie and bovine spongiform encephalopathy in animals. However, the normal functions of PrPC remain largely unknown, particularly in non-neuronal cells. Here we show that stimulation of PrPC with anti-PrP monoclonal antibodies (mAbs) protected mice from lethal infection with influenza A viruses (IAVs), with abundant accumulation of anti-inflammatory M2 macrophages with activated Src family kinases (SFKs) in infected lungs. A SFK inhibitor dasatinib inhibited M2 macrophage accumulation in IAV-infected lungs after treatment with anti-PrP mAbs and abolished the anti-PrP mAb-induced protective activity against lethal influenza infection in mice. We also show that stimulation of PrPC with anti-PrP mAbs induced M2 polarization in peritoneal macrophages through SFK activation in vitro and in vivo. These results indicate that PrPC could activate SFK in macrophages and induce macrophage polarization to an anti-inflammatory M2 phenotype after stimulation with anti-PrP mAbs, thereby eliciting protective activity against lethal infection with IAVs in mice after treatment with anti-PrP mAbs. These results also highlight PrPC as a novel therapeutic target for IAV infection.
Assuntos
Vírus da Influenza A/metabolismo , Pulmão , Macrófagos , Infecções por Orthomyxoviridae , Proteínas PrPC/metabolismo , Transdução de Sinais , Animais , Anticorpos Monoclonais Murinos/farmacologia , Pulmão/metabolismo , Pulmão/patologia , Pulmão/virologia , Macrófagos/metabolismo , Macrófagos/patologia , Macrófagos/virologia , Camundongos , Camundongos Mutantes , Infecções por Orthomyxoviridae/genética , Infecções por Orthomyxoviridae/metabolismo , Infecções por Orthomyxoviridae/patologia , Proteínas PrPC/antagonistas & inibidores , Quinases da Família src/genética , Quinases da Família src/metabolismoRESUMO
The dimorphic yeast Yarrowia lipolytica has an ability to assimilate n-alkanes as carbon and energy sources. In this study, the roles of orthologs of Saccharomyces cerevisiae SEC14 family gene SFH2, which we named SFH21, SFH22, SFH23 and SFH24, of Y. lipolytica were investigated. The transcript levels of SFH21, SFH22 and SFH23, determined by RNA-seq analysis, qRT-PCR analysis and northern blot analysis, were found to increase in the presence of n-alkanes. The deletion mutant of SFH21, but not that of SFH22, SFH23 or SFH24, showed defects in growth in the media containing n-alkanes and in filamentous growth on the solid media containing n-alkanes. Additional deletions of SFH22 and SFH23 significantly exaggerated the defect in filamentous growth of the deletion mutant of SFH21, and expression of SFH22 or SFH24 using the SFH21 promoter partially suppressed the growth defect of the deletion mutant of SFH21 on n-alkanes. These results suggest that SFH2 orthologs are involved in the utilization of n-alkanes and filamentous growth in response to n-alkanes in Y. lipolytica.
Assuntos
Proteínas de Saccharomyces cerevisiae , Yarrowia , Alcanos , Proteínas Fúngicas/genética , Proteínas de Transferência de Fosfolipídeos/genética , Proteínas de Transferência de Fosfolipídeos/metabolismo , Regiões Promotoras Genéticas , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Yarrowia/metabolismoRESUMO
BACKGROUND: Birds harbor specific sex determination and differentiation mechanisms. Although the molecular mechanisms associated with sex determination in somatic cells have been elucidated, those for germ cells remain unclear. RESULTS: Here, we characterized the chicken forkhead box L3 (foxl3)-like gene as a sex-determination factor in sexually indifferent medaka germline stem cells. The foxl3-like gene was cloned by rapid amplification of cDNA ends, and the nucleotide sequence was analyzed. The deduced amino acid sequence was compared with FOXL3 sequences from other species, revealing low identity and similarity scores. Expression analysis of foxl3-like mRNA during gonadogenesis showed female left-gonad-specific temporal expression in an egg incubated from 10 to 16 days, as well as low general expression in certain hatched female chicken organs. Moreover, the amino acid sequence deduced for the FOXL3-like protein displayed low identity with medaka FOXL3, with the FOXL3-like protein specifically localized in the oogonia, whereas medaka FOXL3 was found in sexually indifferent germline stem cells. Furthermore, the timing of expression differed between the foxl3-like gene and that of medaka foxl3. CONCLUSIONS: These results suggest that chicken FOXL3-like protein and medaka FOXL3 differ in terms of their functions as female sex-determination factors.
Assuntos
Fatores de Transcrição Forkhead/genética , Células Germinativas/fisiologia , Processos de Determinação Sexual , Sequência de Aminoácidos , Animais , Sequência de Bases , Aves , Galinhas/genética , Clonagem Molecular , Feminino , Peixes , Oryzias/genéticaRESUMO
Sterols are present in eukaryotic membranes and significantly affect membrane fluidity, permeability, and microdomain formation. They are synthesized in the endoplasmic reticulum (ER) and transported to other organelles and the plasma membrane. Sterols play important roles in the biogenesis and maintenance of mitochondrial membranes. However, the mechanisms underlying ER-to-mitochondrion sterol transport remain to be identified. Here, using purified yeast membrane fractions enriched in ER and mitochondria, we show that the oxysterol-binding protein homologs encoded by the OSH genes in the yeast Saccharomyces cerevisiae mediate sterol transport from the ER to mitochondria. Combined depletion of all seven Osh proteins impaired sterol transport from the ER to mitochondria in vitro; however, sterol transport was recovered at different levels upon adding one of the Osh proteins. Of note, the sterol content in the mitochondrial fraction was significantly decreased in vivo after Osh4 inactivation in a genetic background in which all the other OSH genes were deleted. We also found that Osh5-Osh7 bind cholesterol in vitro We propose a model in which Osh proteins share a common function to transport sterols between membranes, with varying contributions by these proteins, depending on the target membranes. In summary, we have developed an in vitro system to examine intracellular sterol transport and provide evidence for involvement of Osh proteins in sterol transport from the ER to mitochondria in yeast.
Assuntos
Proteínas de Transporte/metabolismo , Colesterol/metabolismo , Retículo Endoplasmático/metabolismo , Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Receptores de Esteroides/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Transporte Biológico Ativo/fisiologia , Proteínas de Transporte/genética , Colesterol/genética , Retículo Endoplasmático/genética , Proteínas de Ligação a Ácido Graxo , Deleção de Genes , Proteínas de Membrana/genética , Mitocôndrias/genética , Receptores de Esteroides/genética , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genéticaRESUMO
The cell wall integrity signaling (CWIS) pathway is involved in fungal cell wall biogenesis. This pathway is composed of sensor proteins, protein kinase C (PKC), and the mitogen-activated protein kinase (MAPK) pathway, and it controls the transcription of many cell wall-related genes. PKC plays a pivotal role in this pathway; deficiencies in PkcA in the model filamentous fungus Aspergillus nidulans and in MgPkc1p in the rice blast fungus Magnaporthe grisea are lethal. This suggests that PKC in filamentous fungi is a potential target for antifungal agents. In the present study, to search for MgPkc1p inhibitors, we carried out in silico screening by three-dimensional (3D) structural modeling and performed growth inhibition tests for M. grisea on agar plates. From approximately 800,000 candidate compounds, we selected Z-705 and evaluated its inhibitory activity against chimeric PKC expressed in Saccharomyces cerevisiae cells in which the kinase domain of native S. cerevisiae PKC was replaced with those of PKCs of filamentous fungi. Transcriptional analysis of MLP1, which encodes a downstream factor of PKC in S. cerevisiae, and phosphorylation analysis of the mitogen-activated protein kinase (MAPK) Mpk1p, which is activated downstream of PKC, revealed that Z-705 specifically inhibited PKCs of filamentous fungi. Moreover, the inhibitory activity of Z-705 was similar to that of a well-known PKC inhibitor, staurosporine. Interestingly, Z-705 inhibited melanization induced by cell wall stress in M. grisea We discuss the relationships between PKC and melanin biosynthesis.IMPORTANCE A candidate inhibitor of filamentous fungal protein kinase C (PKC), Z-705, was identified by in silico screening. A screening system to evaluate the effects of fungal PKC inhibitors was constructed in Saccharomyces cerevisiae Using this system, we found that Z-705 is highly selective for filamentous fungal PKC in comparison with S. cerevisiae PKC. Analysis of the AGS1 mRNA level, which is regulated by Mps1p mitogen-activated protein kinase (MAPK) via PKC, in the rice blast fungus Magnaporthe grisea revealed that Z-705 had a PKC inhibitory effect comparable to that of staurosporine. Micafungin induced hyphal melanization in M. grisea, and this melanization, which is required for pathogenicity of M. grisea, was inhibited by PKC inhibition by both Z-705 and staurosporine. The mRNA levels of 4HNR, 3HNR, and SCD1, which are essential for melanization in M. grisea, were suppressed by both PKC inhibitors.
Assuntos
Aspergillus nidulans/genética , Proteínas Fúngicas/genética , Magnaporthe/genética , Proteína Quinase C/genética , Antifúngicos/farmacologia , Aspergillus nidulans/metabolismo , Proteínas Fúngicas/metabolismo , Magnaporthe/metabolismo , Microrganismos Geneticamente Modificados/genética , Microrganismos Geneticamente Modificados/metabolismo , Proteína Quinase C/metabolismo , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/metabolismo , Transdução de SinaisRESUMO
In this study, we investigated the role of OSH6, which encodes a homolog of the oxysterol-binding protein, in the assimilation of n-alkanes in the yeast Yarrowia lipolytica. The deletion mutant of OSH6 showed growth defects on n-alkanes of 10-16 carbons. In the deletion mutant, production of the functional cytochrome P450 was not observed. However, transcription of ALK1, encoding a major P450 belonging to the CYP52 family that plays a critical role in n-alkane hydroxylation, and further translation of its transcript were noted in the deletion mutant as well as in the wild-type strain. The phospholipid composition was altered and, the ratio of phosphatidylserine (PS) was reduced by the deletion of OSH6. Residues involved in the transport of PS and phosphatidylinositol-4-phosphate in Osh6 of Saccharomyces cerevisiae are conserved in Y. lipolytica Osh6p and substitutions of these residues resulted in a defect in the n-alkane assimilation by Y. lipolytica. From these results, we propose a hypothesis that Osh6p provides an ideal endoplasmic reticulum membrane environment for Alk proteins to have a functional conformation via lipid transport activity in Y. lipolytica.
Assuntos
Alcanos/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Receptores de Esteroides/química , Receptores de Esteroides/metabolismo , Homologia de Sequência de Aminoácidos , Yarrowia/metabolismo , Sequência de Aminoácidos , Transporte Biológico , Proteínas Fúngicas/metabolismo , Deleção de Genes , Fosfatos de Fosfatidilinositol/metabolismo , Fosfatidilserinas/metabolismo , Saccharomyces cerevisiae/metabolismo , Yarrowia/crescimento & desenvolvimentoRESUMO
DDL1 encodes a mitochondrial phospholipase A1 involved in acyl chain remodeling of mitochondrial phospholipids and degradation of cardiolipin in Saccharomyces cerevisiae. The deletion of DDL1 leads to respiratory growth defects. To elucidate the physiological role of DDL1, we screened for genes that, when overexpressed, suppress the respiratory growth defect of the DDL1 deletion mutant. Introduction of COQ8, COQ9, or COQ5, which are involved in coenzyme Q (CoQ) synthesis, using a multicopy vector suppressed the respiratory growth defect of the DDL1 deletion mutant. In contrast, introduction of COQ8 using a multicopy vector did not accelerate the growth of the deletion mutants of TAZ1 or CLD1, which encode an acyltransferase or phospholipase A2, respectively, involved in the remodeling of cardiolipin. These results suggest genetic interactions between the mitochondrial phospholipase A1 gene and the genes involved in CoQ synthesis.
Assuntos
Regulação Fúngica da Expressão Gênica , Genes Fúngicos , Mitocôndrias/enzimologia , Mutação , Fosfolipases A1/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Ubiquinona/biossíntese , Transporte de Elétrons , Deleção de Genes , Vetores Genéticos , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMO
We investigated the role of FAD2, which was predicted to encode a fatty acid desaturase of the n-alkane-assimilating yeast Yarrowia lipolytica. Northern blot analysis suggested that FAD2 transcription was upregulated at low temperature or in the presence of n-alkanes or oleic acid. The FAD2 deletion mutant grew as well as the wild-type strain on glucose, n-alkanes, or oleic acid at 30 °C, but grew at a slower rate at 12 °C, when compared to the wild-type strain. The growth of the FAD2 deletion mutant at 12 °C was restored by the addition of 18:2, but not 18:1, fatty acids. The amount of 18:2 fatty acid in the wild-type strain was increased by the incubation at 12 °C and in the presence of n-octadecane. In contrast, 18:2 fatty acid was not detected in the deletion mutant of FAD2, confirming that FAD2 encodes the Δ12-fatty acid desaturase. These results suggest that Δ12-fatty acid desaturase is involved in the growth of Y. lipolytica at low temperature.
Assuntos
Ácidos Graxos Dessaturases/metabolismo , Temperatura , Yarrowia/enzimologia , Yarrowia/crescimento & desenvolvimento , Ácidos Graxos Dessaturases/deficiência , Ácidos Graxos Dessaturases/genética , Yarrowia/genética , Yarrowia/metabolismoRESUMO
BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive neoplastic diseases, associated with a remarkably poor prognosis. However, the molecular mechanisms underlying the development of PDAC remain elusive. The aim of this study was to identify genes whose expressions are correlated with a poor prognosis in PDAC patients, and to unravel the mechanisms underlying the involvement of these genes in the development of the cancer. METHODS: Global gene expression profiling was conducted in 39 specimens obtained from Japanese patients with PDAC to identify genes whose expressions were correlated with a shorter overall survival. The effect of gene silencing or overexpression of ARHGEF15 in pancreatic cancer cell lines was examined by introducing siRNAs of ARHGEF15 or the ARHGEF15 expression vector. After assessing the effect of ARHGEF15 deregulation on the Rho-family proteins by pull-down assay, wound healing, transwell and cell viability assays were carried out to investigate the cellular phenotypes caused by the perturbation. RESULTS: The global mRNA expression profiling revealed that overexpression of ARHGEF15, a Rho-specific GEF, was significantly associated with a poor prognosis in patients with PDAC. We also found that the depletion of ARHGEF15 by RNA interference in pancreatic cancer cell lines downregulated the activities of molecules of the Rho signaling pathway, including RhoA, Cdc42 and Rac1. Then, we also showed that ARHGEF15 silencing significantly reduced the motility and viability of the cells, while its overexpression resulted in the development of the opposite phenotype in multiple pancreatic cancer cell lines. CONCLUSION: These data suggest that upregulation of ARHGEF15 contributes to the development of aggressive PDAC by increasing the growth and motility of the pancreatic cancer cells, thereby worsening the prognosis of these patients. Therefore, ARHGEF15 could serve as a novel therapeutic target in patients with PDAC.
Assuntos
Adenocarcinoma/genética , Adenocarcinoma/mortalidade , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/mortalidade , Expressão Gênica , Fatores de Troca do Nucleotídeo Guanina/genética , Adenocarcinoma/patologia , Adulto , Idoso , Biomarcadores Tumorais , Carcinoma Ductal Pancreático/patologia , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células , Análise por Conglomerados , Feminino , Perfilação da Expressão Gênica , Inativação Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Prognóstico , RNA Interferente Pequeno/genéticaRESUMO
Yarrowia lipolytica possesses twelve ALK genes, which encode cytochromes P450 in the CYP52 family. In this study, using a Y. lipolytica strain from which all twelve ALK genes had been deleted, strains individually expressing each of the ALK genes were constructed and their roles and substrate specificities were determined by observing their growth on n-alkanes and analyzing fatty acid metabolism. The results suggested that the twelve Alk proteins can be categorized into four groups based on their substrate specificity: Alk1p, Alk2p, Alk9p, and Alk10p, which have significant activities to hydroxylate n-alkanes; Alk4p, Alk5p, and Alk7p, which have significant activities to hydroxylate the ω-terminal end of dodecanoic acid; Alk3p and Alk6p, which have significant activities to hydroxylate both n-alkanes and dodecanoic acid; and Alk8p, Alk11p, and Alk12p, which showed faint or no activities to oxidize these substrates. The involvement of Alk proteins in the oxidation of fatty alcohols and fatty aldehydes was also analyzed by measuring viability of the mutant deleted for twelve ALK genes in medium containing dodecanol and by observing growth on dodecanal of a mutant strain, in which twelve ALK genes were deleted along with four fatty aldehyde dehydrogenase genes. It was suggested that ALK gene(s) is/are involved in the detoxification of dodecanol and the assimilation of dodecanal. These results imply that genes encoding CYP52-family P450s have undergone multiplication and diversification in Y. lipolytica for assimilation of various hydrophobic compounds.
Assuntos
Aldeído Desidrogenase/genética , Alcanos/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Yarrowia/enzimologia , Aldeídos/metabolismo , Sistema Enzimático do Citocromo P-450/classificação , Sistema Enzimático do Citocromo P-450/metabolismo , Ácidos Graxos/metabolismo , Álcoois Graxos/metabolismo , Deleção de Genes , Oxirredução , Especificidade por SubstratoRESUMO
Endocytosis is vital for hyphal tip growth in filamentous fungi and is involved in the tip localization of various membrane proteins. To investigate the function of a Wiskott-Aldrich syndrome protein (WASP) in endocytosis of filamentous fungi, we identified a WASP ortholog-encoding gene, wspA, in Aspergillus nidulans and characterized it. The wspA product, WspA, localized to the tips of germ tubes during germination and actin rings in the subapical regions of mature hyphae. wspA is essential for the growth and functioned in the polarity establishment and maintenance during germination of conidia. We also investigated its function in endocytosis and revealed that endocytosis of SynA, a synaptobrevin ortholog that is known to be endocytosed at the subapical regions of hyphal tips in A. nidulans, did not occur when wspA expression was repressed. These results suggest that WspA plays roles in endocytosis at hyphal tips and polarity establishment during germination.
Assuntos
Aspergillus nidulans/genética , Endocitose/genética , Proteínas Fúngicas/genética , Proteína da Síndrome de Wiskott-Aldrich/genética , Aspergillus nidulans/crescimento & desenvolvimento , Sequência Conservada/genética , Citoesqueleto/genética , Germinação/genética , Proteínas de Fluorescência Verde/genética , Humanos , Hifas/genética , Hifas/crescimento & desenvolvimento , Esporos Fúngicos/genética , Esporos Fúngicos/crescimento & desenvolvimentoRESUMO
In the n-alkane assimilating yeast Yarrowia lipolytica, n-alkanes are oxidized to fatty acids via fatty alcohols and fatty aldehydes, after which they are utilized as carbon sources. Here, we show that four genes (HFD1-HFD4) encoding fatty aldehyde dehydrogenases (FALDHs) are involved in the metabolism of n-alkanes in Y. lipolytica. A mutant, in which all of four HFD genes are deleted (Δhfd1-4 strain), could not grow on n-alkanes of 12-18 carbons; however, the expression of one of those HFD genes restored its growth on n-alkanes. Production of Hfd2Ap or Hfd2Bp, translation products of transcript variants generated from HFD2 by the absence or presence of splicing, also supported the growth of the Δhfd1-4 strain on n-alkanes. The FALDH activity in the extract of the wild-type strain was increased when cells were incubated in the presence of n-decane, whereas this elevation in FALDH activity by n-decane was not observed in Δhfd1-4 strain extract. Substantial FALDH activities were detected in the extracts of Escherichia coli cells expressing the HFD genes. Fluorescent microscopic observation suggests that Hfd3p and Hfd2Bp are localized predominantly in the peroxisome, whereas Hfd1p and Hfd2Ap are localized in both the endoplasmic reticulum and the peroxisome. These results suggest that the HFD multigene family is responsible for the oxidation of fatty aldehydes to fatty acids in the metabolism of n-alkanes, and raise the possibility that Hfd proteins have diversified by gene multiplication and RNA splicing to efficiently assimilate or detoxify fatty aldehydes in Y. lipolytica.
Assuntos
Aldeído Oxirredutases , Alcanos/metabolismo , Proteínas Fúngicas , Família Multigênica/fisiologia , Yarrowia , Aldeído Oxirredutases/genética , Aldeído Oxirredutases/metabolismo , Aldeídos/metabolismo , Sequência de Bases , Ácidos Graxos/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Dados de Sequência Molecular , Oxirredução , Yarrowia/enzimologia , Yarrowia/genéticaRESUMO
In eukaryotic cells, phospholipids are synthesized exclusively in the defined organelles specific for each phospholipid species. To explain the reason for this compartmental specificity in the case of phosphatidylcholine (PC) synthesis, we constructed and characterized a Saccharomyces cerevisiae strain that lacked endogenous phosphatidylethanolamine (PE) methyltransferases but had a recombinant PE methyltransferase from Acetobacter aceti, which was fused with a mitochondrial targeting signal from yeast Pet100p and a 3×HA epitope tag. This fusion protein, which we named as mitopmt, was determined to be localized to the mitochondria by fluorescence microscopy and subcellular fractionation. The expression of mitopmt suppressed the choline auxotrophy of a double deletion mutant of PEM1 and PEM2 (pem1Δpem2Δ) and enabled it to synthesize PC in the absence of choline. This growth suppression was observed even if the Kennedy pathway was inactivated by the repression of PCT1 encoding CTP:phosphocholine cytidylyltransferase, suggesting that PC synthesized in the mitochondria is distributed to other organelles without going through the salvage pathway. The pem1Δpem2Δ strain deleted for PSD1 encoding the mitochondrial phosphatidylserine decarboxylase was able to grow because of the expression of mitopmt in the presence of ethanolamine, implying that PE from other organelles, probably from the ER, was converted to PC by mitopmt. These results suggest that PC could move out of the mitochondria, and raise the possibility that its movement is not under strict directional limitations.
Assuntos
Regulação Fúngica da Expressão Gênica , Mitocôndrias/genética , Fosfatidilcolinas/biossíntese , Fosfatidiletanolamina N-Metiltransferase/genética , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Acetobacter/química , Acetobacter/enzimologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Carboxiliases/deficiência , Carboxiliases/genética , Colina , Colina-Fosfato Citidililtransferase/antagonistas & inibidores , Colina-Fosfato Citidililtransferase/genética , Colina-Fosfato Citidililtransferase/metabolismo , Etanolamina/metabolismo , Teste de Complementação Genética , Isoenzimas/deficiência , Isoenzimas/genética , Mitocôndrias/enzimologia , Proteínas Mitocondriais/deficiência , Proteínas Mitocondriais/genética , Fosfatidiletanolamina N-Metiltransferase/deficiência , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Saccharomyces cerevisiae/enzimologia , Transdução de Sinais , TransgenesRESUMO
In the n-alkane-assimilating yeast Yarrowia lipolytica, the transcription of ALK1, encoding cytochrome P450, that catalyses n-alkane hydroxylation is activated by a complex composed of Yas1p and Yas2p via a promoter element, ARE1, in response to n-alkanes. An Opi1-family transcription factor, Yas3p, represses the transcription by binding to Yas2p in the nucleus when cultured in glucose-containing medium, but it is localized to the ER, presumably through interaction with acidic phospholipids, phosphatidic acid and/or phospho inositides, when cultured in n-alkane-containing medium. Here, to elucidate the mechanisms regulating the localization of Yas3p, point and deletion mutants of Yas3p were constructed and analysed. The substitution of Trp(360) and Cys(361) by Arg abrogated the localization of Yas3p to the ER and decreased ARE1-mediated transcriptional activation by n-alkane. A Yas3p truncation mutant consisting of residues 259-422 did not bind to acidic phospholipids, but it was localized to the ER in the presence of n-alkane, implying the acidic-phospholipid-independent recruitment of this mutant to the ER in response to n-alkane. The W360R and C361R substitutions in this truncation mutant abolished its localization to the ER. The results suggest that these residues are implicated in the acidic phospholipid-independent interaction of Yas3p to the ER.
Assuntos
Retículo Endoplasmático/metabolismo , Proteínas Fúngicas/metabolismo , Yarrowia/genética , Yarrowia/metabolismo , Alcanos/metabolismo , Alcanos/farmacologia , Sistema Enzimático do Citocromo P-450/biossíntese , Sistema Enzimático do Citocromo P-450/genética , Proteínas Fúngicas/genética , Deleção de Genes , Lipossomos/metabolismo , Mutação , Ácidos Fosfatídicos/metabolismo , Fosfolipídeos/metabolismo , Fosfolipídeos/farmacologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transcrição Gênica , Ativação Transcricional , Yarrowia/enzimologia , beta-Galactosidase/metabolismoRESUMO
The yeast Yarrowia lipolytica can assimilate hydrophobic substrates, including n-alkanes and fatty alcohols. Here, eight alcohol dehydrogenase genes, ADH1-ADH7 and FADH, and a fatty alcohol oxidase gene, FAO1, were analyzed to determine their roles in the metabolism of hydrophobic substrates. A mutant deleted for all of these genes (ALCY02 strain) showed severely defective growth on fatty alcohols, and enhanced sensitivity to fatty alcohols in glucose-containing media. The ALCY02 strain grew normally on n-tetradecane or n-hexadecane, but exhibited slightly defective growth on n-decane or n-dodecane. It accumulated more 1-dodecanol and less dodecanoic acid than the wild-type strain when n-dodecane was fed. Expression of ADH1, ADH3 or FAO1, but not that of other ADH genes or FADH, in the ALCY02 strain restored its growth on fatty alcohols. In addition, a triple deletion mutant of ADH1, ADH3 and FAO1 showed similarly defective growth on fatty alcohols and on n-dodecane to the ALCY02 strain. Microscopic observation suggests that Adh1p and Adh3p are localized in the cytosol and Fao1p is in the peroxisome. These results suggest that Adh1p, Adh3p and Fao1p are responsible for the oxidation of exogenous fatty alcohols but play less prominent roles in the oxidation of fatty alcohols derived from n-alkanes.
Assuntos
Álcool Desidrogenase/metabolismo , Oxirredutases do Álcool/metabolismo , Álcoois Graxos/metabolismo , Yarrowia/enzimologia , Yarrowia/metabolismo , Álcool Desidrogenase/genética , Oxirredutases do Álcool/genética , Meios de Cultura/química , Citosol/química , Deleção de Genes , Microscopia Confocal , Microscopia de Fluorescência , Peroxissomos/química , Yarrowia/genética , Yarrowia/crescimento & desenvolvimentoRESUMO
Here, we investigated the roles of YAL1 (FAA1) and FAT1 encoding acyl-CoA synthetases (ACSs) and three additional orthologs of ACS genes FAT2-FAT4 of the yeast Yarrowia lipolytica in the assimilation or utilization of n-alkanes and fatty acids. ACS deletion mutants were generated to characterize their function. The FAT1 deletion mutant exhibited decreased growth on n-alkanes of 10-18 carbons, whereas the FAA1 mutant showed growth reduction on n-alkane of 16 carbons. However, FAT2-FAT4 deletion mutants did not show any growth defects, suggesting that FAT1 and FAA1 are involved in the activation of fatty acids produced during the metabolism of n-alkanes. In contrast, deletions of FAA1 and FAT1-FAT4 conferred no defect in growth on fatty acids. The wild-type strain grew in the presence of cerulenin, an inhibitor of fatty acid synthesis, by utilizing exogenously added fatty acid or fatty acid derived from n-alkane when oleic acid or n-alkane of 18 carbons was supplemented. However, the FAA1 deletion mutant did not grow, indicating a critical role for FAA1 in the utilization of fatty acids. Fluorescent microscopic observation and biochemical analyses suggested that Fat1p is present in the peroxisome and Faa1p is localized in the cytosol and to membranes.