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1.
Nucleic Acids Res ; 52(8): 4541-4555, 2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38499490

RESUMO

Formation of programmed DNA double-strand breaks is essential for initiating meiotic recombination. Genetic studies on Arabidopsis thaliana and Mus musculus have revealed that assembly of a type IIB topoisomerase VI (Topo VI)-like complex, composed of SPO11 and MTOPVIB, is a prerequisite for generating DNA breaks. However, it remains enigmatic if MTOPVIB resembles its Topo VI subunit B (VIB) ortholog in possessing robust ATPase activity, ability to undergo ATP-dependent dimerization, and activation of SPO11-mediated DNA cleavage. Here, we successfully prepared highly pure A. thaliana MTOPVIB and MTOPVIB-SPO11 complex. Contrary to expectations, our findings highlight that MTOPVIB differs from orthologous Topo VIB by lacking ATP-binding activity and independently forming dimers without ATP. Most significantly, our study reveals that while MTOPVIB lacks the capability to stimulate SPO11-mediated DNA cleavage, it functions as a bona fide DNA-binding protein and plays a substantial role in facilitating the dsDNA binding capacity of the MOTOVIB-SPO11 complex. Thus, we illustrate mechanistic divergence between the MTOPVIB-SPO11 complex and classical type IIB topoisomerases.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , DNA Topoisomerases Tipo II , Trifosfato de Adenosina/metabolismo , Arabidopsis/genética , Arabidopsis/enzimologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas Arqueais , Quebras de DNA de Cadeia Dupla , DNA Topoisomerases/metabolismo , DNA Topoisomerases/genética , DNA Topoisomerases Tipo II/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/genética , Endodesoxirribonucleases/metabolismo , Endodesoxirribonucleases/genética , Endodesoxirribonucleases/química , Evolução Molecular , Meiose , Multimerização Proteica
2.
Chembiochem ; 25(3): e202300744, 2024 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-38055188

RESUMO

Hirudins, natural sulfo(glyco)proteins, are clinical anticoagulants that directly inhibit thrombin, a key coagulation factor. Their potent thrombin inhibition primarily results from antagonistic interactions with both the catalytic and non-catalytic sites of thrombin. Hirudins often feature sulfate moieties on Tyr residues in their anionic C-terminus region, enabling strong interactions with thrombin exosite-I and effectively blocking its engagement with fibrinogen. Although sulfotyrosines have been identified in various hirudin variants, the precise relationship between sulfotyrosine and the number of negatively charged amino acids within the anionic-rich C-terminus peptide domain for the binding of thrombin has remained elusive. By using Fmoc-SPPS, hirudin dodecapeptides homologous to the C-terminus of hirudin variants from various leech species were successfully synthesized, and the effect of sulfotyrosine and the number of negatively charged amino acids on hirudin-thrombin interactions was investigated. Our findings did not reveal any synergistic effect between an increasing number of sulfotyrosines or negatively charged amino acids and their inhibitory activity on thrombin or fibrinolysis in the assays, despite a higher binding level toward thrombin in the sulfated dodecapeptide Hnip_Hirudin was observed in SPR analysis.


Assuntos
Hirudinas , Trombina , Tirosina/análogos & derivados , Hirudinas/farmacologia , Hirudinas/química , Hirudinas/metabolismo , Aminoácidos , Peptídeos/farmacologia , Sítios de Ligação
3.
Int J Mol Sci ; 24(12)2023 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-37372979

RESUMO

TRIM28/KAP1/TIF1ß is a crucial epigenetic modifier. Genetic ablation of trim28 is embryonic lethal, although RNAi-mediated knockdown in somatic cells yields viable cells. Reduction in TRIM28 abundance at the cellular or organismal level results in polyphenism. Posttranslational modifications such as phosphorylation and sumoylation have been shown to regulate TRIM28 activity. Moreover, several lysine residues of TRIM28 are subject to acetylation, but how acetylation of TRIM28 affects its functions remains poorly understood. Here, we report that, compared with wild-type TRIM28, the acetylation-mimic mutant TRIM28-K304Q has an altered interaction with Krüppel-associated box zinc-finger proteins (KRAB-ZNFs). The TRIM28-K304Q knock-in cells were created in K562 erythroleukemia cells by CRISPR-Cas9 (Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein nuclease 9) gene editing method. Transcriptome analysis revealed that TRIM28-K304Q and TRIM28 knockout K562 cells had similar global gene expression profiles, yet the profiles differed considerably from wild-type K562 cells. The expression levels of embryonic-related globin gene and a platelet cell marker integrin-beta 3 were increased in TRIM28-K304Q mutant cells, indicating the induction of differentiation. In addition to the differentiation-related genes, many zinc-finger-proteins genes and imprinting genes were activated in TRIM28-K304Q cells; they were inhibited by wild-type TRIM28 via binding with KRAB-ZNFs. These results suggest that acetylation/deacetylation of K304 in TRIM28 constitutes a switch for regulating its interaction with KRAB-ZNFs and alters the gene regulation as demonstrated by the acetylation mimic TRIM28-K304Q.


Assuntos
Processamento de Proteína Pós-Traducional , Proteínas Repressoras , Humanos , Proteínas Repressoras/genética , Células K562 , Acetilação , Proteína 28 com Motivo Tripartido/genética , Proteína 28 com Motivo Tripartido/metabolismo , Mutação , Expressão Gênica , Zinco/metabolismo
4.
J Biomed Sci ; 29(1): 20, 2022 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-35313878

RESUMO

BACKGROUND: Colorectal cancer (CRC) is a worldwide cancer with rising annual incidence. New medications for patients with CRC are still needed. Recently, fluorescent chemical probes have been developed for cancer imaging and therapy. Signal transducer and activator of transcription 1 (STAT1) has complex functions in tumorigenesis and its role in CRC still needs further investigation. METHODS: RNA sequencing datasets in the NCBI GEO repository were analyzed to investigate the expression of STAT1 in patients with CRC. Xenograft mouse models, tail vein injection mouse models, and azoxymethane/dextran sodium sulfate (AOM/DSS) mouse models were generated to study the roles of STAT1 in CRC. A ligand-based high-throughput virtual screening approach combined with SWEETLEAD chemical database analysis was used to discover new STAT1 inhibitors. A newly designed and synthesized fluorescently labeled 4',5,7-trihydroxyisoflavone (THIF) probe (BODIPY-THIF) elucidated the mechanistic actions of STAT1 and THIF in vitro and in vivo. Colonosphere formation assay and chick chorioallantoic membrane assay were used to evaluate stemness and angiogenesis, respectively. RESULTS: Upregulation of STAT1 was observed in patients with CRC and in mouse models of AOM/DSS-induced CRC and metastatic CRC. Knockout of STAT1 in CRC cells reduced tumor growth in vivo. We then combined a high-throughput virtual screening approach and analysis of the SWEETLEAD chemical database and found that THIF, a flavonoid abundant in soybeans, was a novel STAT1 inhibitor. THIF inhibited STAT1 phosphorylation and might bind to the STAT1 SH2 domain, leading to blockade of STAT1-STAT1 dimerization. The results of in vitro and in vivo binding studies of THIF and STAT1 were validated. The pharmacological treatment with BODIPY-THIF or ablation of STAT1 via a CRISPR/Cas9-based strategy abolished stemness and angiogenesis in CRC. Oral administration of BODIPY-THIF attenuated colitis symptoms and tumor growth in the mouse model of AOM/DSS-induced CRC. CONCLUSIONS: This study demonstrates that STAT1 plays an oncogenic role in CRC. BODIPY-THIF is a new chemical probe inhibitor of STAT1 that reduces stemness and angiogenesis in CRC. BODIPY-THIF can be a potential tool for CRC therapy as well as cancer cell imaging.


Assuntos
Neoplasias Colorretais , Animais , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Humanos , Camundongos , Camundongos Knockout , Células-Tronco Neoplásicas/patologia , Neovascularização Patológica/tratamento farmacológico , Neovascularização Patológica/genética , Oncogenes , Fator de Transcrição STAT1/genética , Fator de Transcrição STAT1/metabolismo
5.
Int J Mol Sci ; 23(12)2022 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-35743282

RESUMO

TRIM28 is a scaffold protein that interacts with DNA-binding proteins and recruits corepressor complexes to cause gene silencing. TRIM28 contributes to physiological functions such as cell growth and differentiation. In the chronic myeloid leukemia cell line K562, we edited TRIM28 using CRISPR/Cas9 technology, and the complete and partial knockout (KO) cell clones were obtained and confirmed using quantitative droplet digital PCR (ddPCR) technology. The amplicon sequencing demonstrated no off-target effects in our gene editing experiments. The TRIM28 KO cells grew slowly and appeared red, seeming to have a tendency towards erythroid differentiation. To understand how TRIM28 controls K562 cell proliferation and differentiation, transcriptome profiling analysis was performed in wild-type and KO cells to identify TRIM28-regulated genes. Some of the RNAs that encode the proteins regulating the cell cycle were increased (such as p21) or decreased (such as cyclin D2) in TRIM28 KO cell clones; a tumor marker, the MAGE (melanoma antigen) family, which is involved in cell proliferation was reduced. Moreover, we found that knockout of TRIM28 can induce miR-874 expression to downregulate MAGEC2 mRNA via post-transcriptional regulation. The embryonic epsilon-globin gene was significantly increased in TRIM28 KO cell clones through the downregulation of transcription repressor SOX6. Taken together, we provide evidence to demonstrate the regulatory network of TRIM28-mediated cell growth and erythroid differentiation in K562 leukemia cells.


Assuntos
Edição de Genes , MicroRNAs , Sistemas CRISPR-Cas , Proliferação de Células/genética , Expressão Gênica , Subunidades de Hemoglobina/genética , Subunidades de Hemoglobina/metabolismo , Humanos , Células K562 , Fatores de Transcrição/metabolismo , Proteína 28 com Motivo Tripartido/metabolismo
6.
Int J Mol Sci ; 21(19)2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-33008113

RESUMO

The tripartite motif-containing protein 28 (TRIM28) is a transcription corepressor, interacting with histone deacetylase and methyltransferase complexes. TRIM28 is a crucial regulator in development and differentiation. We would like to investigate its function and regulation in adipogenesis. Knockdown of Trim28 by transducing lentivirus-carrying shRNAs impairs the differentiation of 3T3-L1 preadipocytes, demonstrated by morphological observation and gene expression analysis. To understand the molecular mechanism of Trim28-mediated adipogenesis, the RNA-seq was performed to find out the possible Trim28-regulated genes. Dlk1 (delta-like homolog 1) was increased in Trim28 knockdown 3T3-L1 cells both untreated and induced to differentiation. Dlk1 is an imprinted gene and known as an inhibitor of adipogenesis. Further knockdown of Dlk1 in Trim28 knockdown 3T3-L1 would rescue cell differentiation. The epigenetic analysis showed that DNA methylation of Dlk1 promoter and differentially methylated regions (DMRs) was not altered significantly in Trim28 knockdown cells. However, compared to control cells, the histone methylation on the Dlk1 promoter was increased at H3K4 and decreased at H3K27 in Trim28 knockdown cells. Finally, we found Trim28 might be recruited by transcription factor E2f1 to regulate Dlk1 expression. The results imply Trim28-Dlk1 axis is critical for adipogenesis.


Assuntos
Adipogenia/genética , Proteínas de Ligação ao Cálcio/genética , Metilação de DNA/genética , Proteínas de Membrana/genética , Proteína 28 com Motivo Tripartido/genética , Células 3T3-L1 , Adipócitos/metabolismo , Animais , Diferenciação Celular/genética , Regulação da Expressão Gênica no Desenvolvimento/genética , Camundongos , RNA-Seq , Transdução de Sinais/genética
7.
Environ Monit Assess ; 191(7): 435, 2019 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-31201540

RESUMO

Serious environmental problems have accompanied remarkable global economic growth for decades. To assist managers in the semiconductor industry with economic and environmental management, this study executes DuPont analysis to examine economic impacts from the effective implementation of sustainability initiatives. We propose a two-stage process including economic development efficiency and environmental protection efficiency through the dynamic data envelopment analysis (DDEA) to reflect the characteristics of eco-efficiency. Through DuPont analysis, the main finding shows the potential improvement in firms' return on equity (ROE) by efficiently utilizing assets to generate sales quickly.Relative to economic development efficiency, the firms show lower scores and higher standard deviations in the environmental protection ability, thus denoting a large gap in the level of environmental protection production technology. The findings in this study reveal that the financial foundations and sustainable development of industries should be improved simultaneously even though specific levels of semiconductor industrial eco-efficiency improvement vary among companies in Taiwan.


Assuntos
Desenvolvimento Econômico , Monitoramento Ambiental/métodos , Indústrias/tendências , Semicondutores/tendências , Desenvolvimento Sustentável/tendências , Comércio , Eficiência , Monitoramento Ambiental/economia , Taiwan
8.
Transfusion ; 58(4): 1054-1064, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29399809

RESUMO

BACKGROUND: The P1 /P2 phenotypic polymorphism is one of the earliest blood groups discovered in humans. These blood groups have been connected to different levels of expression of the A4GALT gene in P1 and P2 red blood cells; however, the detailed molecular genetic mechanism that leads to these two phenotypes has not been established. STUDY DESIGN AND METHODS: After our previous identification of an association between the single-nucleotide polymorphisms (SNPs) rs2143918 and rs5751348 in A4GALT gene and the P1 /P2 phenotype, we conduct a survey of transcription factors that might connect these SNPs with the differential expression of the P1 -A4GALT and P2 -A4GALT alleles. An in silico analysis of potential transcription factor binding motifs within the polymorphic SNPs rs2143918 and rs5751348 genomic regions was performed, and this was followed by reporter assays examining the candidate transcription factors, gene expression profiling, electrophoretic mobility shift assays, and P1 -A4GALT and P2 -A4GALT allelic expression analysis. RESULTS: The results revealed that the differential binding of transcription factor early growth response 1 to the SNP rs5751348 genomic region with the different genotypes in the A4GALT gene leads to differential activation of P1 -A4GALT and P2 -A4GALT expression. CONCLUSION: The present investigation, together with our previous study (Lai et al., Transfusion 2014;54:3222-31), have elucidated the molecular genetic details associated with the P1 /P2 blood groups.


Assuntos
Proteína 1 de Resposta de Crescimento Precoce/fisiologia , Galactosiltransferases/biossíntese , Regulação da Expressão Gênica , Polimorfismo de Nucleotídeo Único , Alelos , Simulação por Computador , Fatores de Transcrição de Resposta de Crescimento Precoce/fisiologia , Ensaio de Desvio de Mobilidade Eletroforética , Galactosiltransferases/genética , Perfilação da Expressão Gênica , Genes Reporter , Células HEK293 , Humanos , Ligação Proteica , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Transcrição Gênica
9.
Nucleic Acids Res ; 44(13): 6242-51, 2016 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-27131790

RESUMO

During DNA double-strand break and replication fork repair by homologous recombination, the RAD51 recombinase catalyzes the DNA strand exchange reaction via a helical polymer assembled on single-stranded DNA, termed the presynaptic filament. Our published work has demonstrated a dual function of the SWI5-SFR1 complex in RAD51-mediated DNA strand exchange, namely, by stabilizing the presynaptic filament and maintaining the catalytically active ATP-bound state of the filament via enhancement of ADP release. In this study, we have strived to determine the basis for physical and functional interactions between Mus musculus SWI5-SFR1 and RAD51. We found that SWI5-SFR1 preferentially associates with the oligomeric form of RAD51. Specifically, a C-terminal domain within SWI5 contributes to RAD51 interaction. With specific RAD51 interaction defective mutants of SWI5-SFR1 that we have isolated, we show that the physical interaction is indispensable for the stimulation of the recombinase activity of RAD51. Our results thus help establish the functional relevance of the trimeric RAD51-SWI5-SFR1 complex and provide insights into the mechanistic underpinnings of homology-directed DNA repair in mammalian cells.


Assuntos
Recombinação Homóloga/genética , Proteínas Nucleares/química , Rad51 Recombinase/química , Trifosfato de Adenosina/metabolismo , Animais , Quebras de DNA de Cadeia Dupla , Reparo do DNA/genética , Replicação do DNA/genética , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Camundongos , Complexos Multiproteicos/química , Complexos Multiproteicos/metabolismo , Proteínas Nucleares/metabolismo , Rad51 Recombinase/metabolismo
10.
Int J Mol Sci ; 19(9)2018 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-30227633

RESUMO

We have reported the propensity of a DNA sequence containing CCG repeats to form a stable i-motif tetraplex structure in the absence of ligands. Here we show that an i-motif DNA sequence may transition to a base-extruded duplex structure with a GGCC tetranucleotide tract when bound to the (CoII)-mediated dimer of chromomycin A3, CoII(Chro)2. Biophysical experiments reveal that CCG trinucleotide repeats provide favorable binding sites for CoII(Chro)2. In addition, water hydration and divalent metal ion (CoII) interactions also play a crucial role in the stabilization of CCG trinucleotide repeats (TNRs). Our data furnish useful structural information for the design of novel therapeutic strategies to treat neurological diseases caused by repeat expansions.


Assuntos
Cromomicina A3/farmacologia , Cobalto/farmacologia , Complexos de Coordenação/farmacologia , DNA/química , Conformação de Ácido Nucleico/efeitos dos fármacos , Repetições de Trinucleotídeos/efeitos dos fármacos , Cromomicina A3/química , Cobalto/química , Complexos de Coordenação/química , Cristalografia por Raios X , Descoberta de Drogas , Modelos Moleculares
11.
Biochemistry ; 55(31): 4366-74, 2016 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-27428767

RESUMO

Some trans-prenyltransferases, such as long-chain C40 octaprenyl diphosphate synthase (OPPS), short-chain C15 farnesyl diphosphate synthase (FPPS), and C20 geranylgeranyl diphosphate synthase (GGPPS), are important drug targets. These enzymes catalyze chain elongation of FPP or geranyl diphosphate (GPP) through condensation reactions with isopentenyl diphosphate (IPP), forming designated numbers of trans-double bonds in the final products. To facilitate drug discovery, we report here a sensitive and reliable fluorescence-based assay for monitoring their activities in real time. MANT-O-GPP, a fluorescent analogue of FPP, was used as an alternative substrate and converted by the wild-type OPPS and the engineered FPPS and GGPPS into sufficiently long products with enhanced fluorescence intensities. This fluorescence probe was used to reveal the inhibitory mechanism of zoledronate, a bisphosphonate drug that targets human FPPS and possibly GGPPS.


Assuntos
Dimetilaliltranstransferase/antagonistas & inibidores , Dimetilaliltranstransferase/química , Corantes Fluorescentes/química , Sondas Moleculares/química , Fosfatos de Poli-Isoprenil/química , Sesquiterpenos/química , Alquil e Aril Transferases/antagonistas & inibidores , Alquil e Aril Transferases/química , Alquil e Aril Transferases/genética , Substituição de Aminoácidos , Dimetilaliltranstransferase/genética , Difosfonatos/farmacologia , Descoberta de Drogas , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Farnesiltranstransferase/antagonistas & inibidores , Farnesiltranstransferase/química , Farnesiltranstransferase/genética , Geraniltranstransferase/antagonistas & inibidores , Geraniltranstransferase/química , Geraniltranstransferase/genética , Humanos , Imidazóis/farmacologia , Cinética , Modelos Moleculares , Técnicas de Sonda Molecular , Mutagênese Sítio-Dirigida , Conformação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas de Saccharomyces cerevisiae/antagonistas & inibidores , Especificidade por Substrato , Ácido Zoledrônico
12.
J Biol Chem ; 290(32): 19863-73, 2015 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-26088134

RESUMO

DMC1 and RAD51 are conserved recombinases that catalyze homologous recombination. DMC1 and RAD51 share similar properties in DNA binding, DNA-stimulated ATP hydrolysis, and catalysis of homologous DNA strand exchange. A large body of evidence indicates that attenuation of ATP hydrolysis leads to stabilization of the RAD51-ssDNA presynaptic filament and enhancement of DNA strand exchange. However, the functional relationship of ATPase activity, presynaptic filament stability, and DMC1-mediated homologous DNA strand exchange has remained largely unexplored. To address this important question, we have constructed several mutant variants of human DMC1 and characterized them biochemically to gain mechanistic insights. Two mutations, K132R and D223N, that change key residues in the Walker A and B nucleotide-binding motifs ablate ATP binding and render DMC1 inactive. On the other hand, the nucleotide-binding cap D317K mutant binds ATP normally but shows significantly attenuated ATPase activity and, accordingly, forms a highly stable presynaptic filament. Surprisingly, unlike RAD51, presynaptic filament stabilization achieved via ATP hydrolysis attenuation does not lead to any enhancement of DMC1-catalyzed homologous DNA pairing and strand exchange. This conclusion is further supported by examining wild-type DMC1 with non-hydrolyzable ATP analogues. Thus, our results reveal an important mechanistic difference between RAD51 and DMC1.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Pareamento Cromossômico , DNA de Cadeia Simples/metabolismo , Proteínas de Ligação a DNA/metabolismo , Recombinação Homóloga , Rad51 Recombinase/metabolismo , Monofosfato de Adenosina/química , Monofosfato de Adenosina/metabolismo , Trifosfato de Adenosina/química , Trifosfato de Adenosina/metabolismo , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/genética , DNA de Cadeia Simples/química , DNA de Cadeia Simples/genética , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Exodesoxirribonucleases/metabolismo , Expressão Gênica , Humanos , Hidrólise , Dados de Sequência Molecular , Mutação , Conformação de Ácido Nucleico , Motivos de Nucleotídeos , Ligação Proteica , Rad51 Recombinase/química , Rad51 Recombinase/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
13.
Bioorg Med Chem ; 24(13): 3035-3042, 2016 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-27240464

RESUMO

Severe acute respiratory syndrome (SARS) led to a life-threatening form of atypical pneumonia in late 2002. Following that, Middle East Respiratory Syndrome (MERS-CoV) has recently emerged, killing about 36% of patients infected globally, mainly in Saudi Arabia and South Korea. Based on a scaffold we reported for inhibiting neuraminidase (NA), we synthesized the analogues and identified compounds with low micromolar inhibitory activity against 3CL(pro) of SARS-CoV and MERS-CoV. Docking studies show that a carboxylate present at either R(1) or R(4) destabilizes the oxyanion hole in the 3CL(pro). Interestingly, 3f, 3g and 3m could inhibit both NA and 3CL(pro) and serve as a starting point to develop broad-spectrum antiviral agents.


Assuntos
Coronavírus da Síndrome Respiratória do Oriente Médio , Peptídeo Hidrolases/metabolismo , Inibidores de Proteases/síntese química , Inibidores de Proteases/farmacologia , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave , Antivirais/síntese química , Antivirais/química , Antivirais/farmacologia , Ativação Enzimática/efeitos dos fármacos , Humanos , Concentração Inibidora 50 , Coronavírus da Síndrome Respiratória do Oriente Médio/efeitos dos fármacos , Coronavírus da Síndrome Respiratória do Oriente Médio/enzimologia , Modelos Moleculares , Simulação de Acoplamento Molecular , Peptídeo Hidrolases/química , Inibidores de Proteases/química , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/efeitos dos fármacos , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/enzimologia
14.
Nucleic Acids Res ; 42(1): 349-58, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24078249

RESUMO

Homologous recombination catalyzed by the RAD51 recombinase eliminates deleterious DNA lesions from the genome. In the presence of ATP, RAD51 forms a nucleoprotein filament on single-stranded DNA, termed the presynaptic filament, to initiate homologous recombination-mediated DNA double-strand break repair. The SWI5-SFR1 complex stabilizes the presynaptic filament and enhances its ability to mediate the homologous DNA pairing reaction. Here we characterize the RAD51 presynaptic filament stabilization function of the SWI5-SFR1 complex using optical tweezers. Biochemical experiments reveal that SWI5-SFR1 enhances ATP hydrolysis by single-stranded DNA-bound RAD51. Importantly, we show that SWI5-SFR1 acts by facilitating the release of ADP from the presynaptic filament. Our results thus provide mechanistic understanding of the function of SWI5-SFR1 in RAD51-mediated DNA recombination.


Assuntos
Difosfato de Adenosina/metabolismo , Rad51 Recombinase/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo , Trifosfato de Adenosina/metabolismo , Meiose/genética , Pinças Ópticas , Recombinação Genética
15.
J Am Chem Soc ; 137(30): 9685-93, 2015 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-26168351

RESUMO

Galectin-3 binding protein (Gal-3BP) is a large hyperglycosylated protein that acts as a ligand for several galectins through glycan-dependent interactions. Gal-3BP can induce galectin-mediated tumor cell aggregation to increase the survival of cancer cells in the bloodstream during the metastatic process. However, the galectin interacting with Gal-3BP and its binding specificity has not been identified and structurally elucidated, mainly due to the limitation of mass spectrometry in glycan sequencing. To understand the role of Gal-3BP, we here used liquid chromatography-mass spectrometry combined with specific exoglycosidase reactions to determine the sequences of N-glycans on Gal-3BP from MCF-7 and MDA-MB-231 cells, especially the sequences with terminal sialylation and fucosylation, and addition of LacNAc repeat structures. The N-glycans from both strains are complex type with terminal α2,3-sialidic acid and core fucose linkages, with additional α1,2- and α1,3 fucose linkages found in MCF-7 cells. Compared with that from MCF-7, the Gal-3BP from MDA-MB-231 cells had fewer tetra-antennary structures, only α1,6-linked core fucoses, and more LacNAc repeat structures; the MDA-MB-231 cells had no surface galectin-3 but used surface galectin-1 for interaction with Gal-3BP to form large oligomers and cell aggregates. This study elucidates the specificity of Gal-3BP interacting with galectin-1 and the role of Gal-3BP in cancer cell aggregation and metastasis.


Assuntos
Neoplasias da Mama/patologia , Galectina 1/metabolismo , Galectina 3/metabolismo , Metástase Neoplásica/patologia , Proteínas Sanguíneas , Neoplasias da Mama/metabolismo , Agregação Celular , Linhagem Celular Tumoral , Feminino , Galectinas , Humanos , Células MCF-7 , Ligação Proteica
16.
Nucleic Acids Res ; 40(14): 6558-69, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22492707

RESUMO

Homologous recombination (HR) represents a major error-free pathway to eliminate pre-carcinogenic chromosomal lesions. The DNA strand invasion reaction in HR is mediated by a helical filament of the Rad51 recombinase assembled on single-stranded DNA that is derived from the nucleolytic processing of the primary lesion. Recent studies have found that the human and mouse Swi5 and Sfr1 proteins form a complex that influences Rad51-mediated HR in cells. Here, we provide biophysical evidence that the mouse Swi5-Sfr1 complex has a 1:1 stoichiometry. Importantly, the Swi5-Sfr1 complex, but neither Swi5 nor Sfr1 alone, physically interacts with Rad51 and stimulates Rad51-mediated homologous DNA pairing. This stimulatory effect stems from the stabilization of the Rad51-ssDNA presynaptic filament. Moreover, we provide evidence that the RSfp (rodent Sfr1 proline rich) motif in Sfr1 serves as a negative regulatory element. These results thus reveal an evolutionarily conserved function in the Swi5-Sfr1 complex and furnish valuable information as to the regulatory role of the RSfp motif that is specific to the mammalian Sfr1 orthologs.


Assuntos
Proteínas Nucleares/metabolismo , Rad51 Recombinase/metabolismo , Motivos de Aminoácidos , Animais , Dimerização , Camundongos , Proteínas Nucleares/antagonistas & inibidores , Proteínas Nucleares/química , Multimerização Proteica
17.
Biochemistry ; 52(16): 2783-92, 2013 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-23534508

RESUMO

Previously we showed that yeast geranylgeranyl diphosphate synthase (GGPPS) becomes an inactive monomer when the first N-terminal helix involved in dimerization is deleted. This raises questions regarding why dimerization is required for GGPPS activity and which amino acids in the dimer interface are essential for dimerization-mediated activity. According to the GGPPS crystal structure, three amino acids (N101, N104, and Y105) located in the helix F of one subunit are near the active site of the other subunit. As presented here, when these residues were replaced individually with Ala caused insignificant activity changes, N101A/Y105A and N101A/N104A but not N104A/Y105A showed remarkably decreased k(cat) values (200-250-fold). The triple mutant N101A/N104A/Y105A displayed no detectable activity, although dimer was retained in these mutants. Because N101 and Y105 form H-bonds with H139 and R140 in the other subunit, respectively, we generated H139A/R140A double mutant and found it was inactive and became monomeric. Therefore, the multiple mutations apparently influence the integrity of the catalytic site due to the missing H-bonding network. Moreover, Met111, also on the highly conserved helix F, was necessary for dimer formation and enzyme activity. When Met111 was replaced with Glu, the negative-charged repulsion converted half of the dimer into a monomer. In conclusion, the H-bonds mainly through N101 for maintaining substrate binding stability and the hydrophobic interaction of M111 in dimer interface are essential for activity of yeast GGPPS.


Assuntos
Farnesiltranstransferase/química , Farnesiltranstransferase/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Sequência de Aminoácidos , Substituição de Aminoácidos , Sequência de Bases , Domínio Catalítico , Farnesiltranstransferase/genética , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Dados de Sequência Molecular , Mutação , Multimerização Proteica , Estrutura Quaternária de Proteína , Estrutura Secundária de Proteína , Saccharomyces cerevisiae/enzimologia , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Homologia de Sequência de Aminoácidos
18.
J Chem Inf Model ; 53(9): 2299-311, 2013 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-23919676

RESUMO

Bisphosphonates are potent inhibitors of farnesyl pyrophosphate synthase (FPPS) and geranylgeranyl diphosphate synthase (GGPPS). Current bisphosphonate drugs (e.g., Fosamax and Zometa) are highly efficacious in the treatment of bone diseases such as osteoporosis, Paget's disease, and tumor-induced osteolysis, but they are often less potent in blood and soft-tissue due to their phosphate moieties. The discovery of nonbisphosphonate inhibitors of FPPS and/or GGPPS for the treatment of bone diseases and cancers is, therefore, a current goal. Here, we propose a moiety-linkage-based method, combining a site-moiety map with chemical structure rules (CSRs), to discover nonbisphosphonate inhibitors from thousands of commercially available compounds and known crystal structures. Our moiety-linkage map reveals the binding mechanisms and inhibitory efficacies of 51 human GGPPS (hGGPPS) inhibitors. To the best of our knowledge, we are the first team to discover two novel selective nonbisphosphonate inhibitors, which bind to the inhibitory site of hGGPPS, using CSRs and site-moiety maps. These two compounds can be considered as a novel lead for the potent inhibitors of hGGPPS for the treatment of cancers and mevalonate-pathway diseases. Moreover, based on our moiety-linkage map, we identified two key residues of hGGPPS, K202, and K212, which play an important role for the inhibitory effect of zoledronate (IC50 = 3.4 µM and 2.4 µM, respectively). This result suggests that our method can discover specific hGGPPS inhibitors across multiple prenyltransferases. These results show that the compounds that highly fit our moiety-linkage map often inhibit hGGPPS activity and induce tumor cell apoptosis. We believe that our method is useful for discovering potential inhibitors and binding mechanisms for pharmaceutical targets.


Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Farnesiltranstransferase/antagonistas & inibidores , Sítios de Ligação , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Inibidores Enzimáticos/metabolismo , Farnesiltranstransferase/química , Farnesiltranstransferase/genética , Farnesiltranstransferase/metabolismo , Humanos , Modelos Moleculares , Mutagênese Sítio-Dirigida , Conformação Proteica , Especificidade por Substrato
19.
Ann Oper Res ; : 1-27, 2023 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-37361071

RESUMO

It is necessary to emphasize both the process and results of performance management to find the balance between quality and quantity needed to ensure the sustainable development of universities to make the best use of limited educational resources and meet the diverse needs of students. This study applies failure mode and effects analysis (FMEA) to analyze obstacles to university sustainability by constructing complete risk assessment modes and reference indicators. The neutrosophic set theory was incorporated into the FMEA to account for information uncertainty and asymmetry. A specialist team then evaluated the importance of the risk factors using neutrosophic indifference threshold-based attribute ratio analysis to determine objective weights for the risk factors. Furthermore, the neutrosophic technique for order preference by similarity to the ideal solution based on aspiration level (N-TOPSIS-AL) is employed to aggregate the total risk scores of the failure modes. Using neutrosophic sets to measure truth, falsity, and indeterminacy in the assessment significantly improve the adaptability of the fuzzy theory to real-world problems. The study results indicate that when assessing university affairs management and analyzing possible risks, priority must be given to the occurrence of risks and that the lack of educational facilities is the riskiest item in the specialist assessment. The proposed assessment model can be applied as a basis for university sustainability assessments to accelerate the development of other forward-looking approaches.

20.
J Agric Food Chem ; 71(35): 13014-13023, 2023 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-37566786

RESUMO

Antrodia cinnamomea is an endemic species found in Taiwan, known for its medicinal properties in treating various discomforts, including inflammation, diarrhea, abdominal pain, and other diseases. A. cinnamomea contains terpenoids that exhibit numerous bioactivities, making them potential food additives. This discovery piqued our interest in uncovering their biosynthetic pathway. Herein, we conducted functional and structural characterization of a sesquiterpene synthase Cop4 from A. cinnamomea (AcCop4). Through gas chromatography-mass spectrometry analysis, we observed that AcCop4 catalyzes the cyclization of farnesyl pyrophosphate (FPP), primarily producing cubebol. Cubebol is widely used as a long-lasting cooling and refreshing agent in the food industry. The structure of AcCop4, complexed with pyrophosphate and magnesium ions, revealed the closure of the active site facilitated by R311. Interestingly, binding of pyrophosphate and magnesium ions did not cause any significant conformational change in the G1/2 helix of AcCop4, indicating that the apo form is not fully open. This high-resolution structure serves as a solid basis for understanding the biosynthetic mechanism of AcCop4 and supports further production and modification of cubebol for its applications in the food industry.


Assuntos
Antrodia , Sesquiterpenos , Difosfatos/metabolismo , Magnésio/metabolismo , Sesquiterpenos/metabolismo , Antrodia/metabolismo
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