RESUMO
Secondary structure is a principal determinant of lncRNA function, predominantly regarding scaffold formation and interfaces with target molecules. Noncanonical secondary structures that form in nucleic acids have known roles in regulating gene expression and include G-quadruplexes (G4s), intercalated motifs (iMs), and R-loops (RLs). In this paper, we used the computational tools G4-iM Grinder and QmRLFS-finder to predict the formation of each of these structures throughout the lncRNA transcriptome in comparison to protein-coding transcripts. The importance of the predicted structures in lncRNAs in biological contexts was assessed by combining our results with publicly available lncRNA tissue expression data followed by pathway analysis. The formation of predicted G4 (pG4) and iM (piM) structures in select lncRNA sequences was confirmed in vitro using biophysical experiments under near-physiological conditions. We find that the majority of the tested pG4s form highly stable G4 structures, and identify many previously unreported G4s in biologically important lncRNAs. In contrast, none of the piM sequences are able to form iM structures, consistent with the idea that RNA is unable to form stable iMs. Unexpectedly, these C-rich sequences instead form Z-RNA structures, which have not been previously observed in regions containing cytosine repeats and represent an interesting and underexplored target for protein-RNA interactions. Our results highlight the prevalence and potential structure-associated functions of noncanonical secondary structures in lncRNAs, and show G4 and Z-RNA structure formation in many lncRNA sequences for the first time, furthering the understanding of the structure-function relationship in lncRNAs.
Assuntos
Quadruplex G , RNA Longo não Codificante , RNA , RNA Longo não Codificante/genética , Proteínas/genéticaRESUMO
Although the impact of telomeres on physiology stands well established, a question remains: how do telomeres impact cellular functions at a molecular level? This is because current understanding limits the influence of telomeres to adjacent subtelomeric regions despite the wide-ranging impact of telomeres. Emerging work in two distinct aspects offers opportunities to bridge this gap. First, telomere-binding factors were found with non-telomeric functions. Second, locally induced DNA secondary structures called G-quadruplexes are notably abundant in telomeres, and gene regulatory regions genome wide. Many telomeric factors bind to G-quadruplexes for non-telomeric functions. Here we discuss a more general model of how telomeres impact the non-telomeric genome - through factors that associate at telomeres and genome wide - and influence cell-intrinsic functions, particularly aging, cancer, and pluripotency.
Assuntos
Quadruplex G , Telômero , Telômero/genética , Telômero/metabolismo , DNA/metabolismo , HeterocromatinaRESUMO
Metal ions are essential components for the survival of living organisms. For most species, intracellular and extracellular ionic conditions differ significantly. As G-quadruplexes (G4s) are ion-dependent structures, changes in the [Na+]/[K+] ratio may affect the folding of genomic G4s. More than 11000 putative G4 sequences in the human genome (hg19) contain at least two runs of three continuous cytosines, and these mixed G/C-rich sequences may form a quadruplex or a competing hairpin structure based on G-C base pairing. In this study, we examine how the [Na+]/[K+] ratio influences the structures of G/C-rich sequences. The natural G4 structure with a 9-nt long central loop, CEBwt, was chosen as a model sequence, and the loop bases were gradually replaced by cytosines. The series of CEB mutations revealed that the presence of cytosines in G4 loops does not prevent G4 folding or decrease G4 stability but increases the probability of forming a competing structure, either a hairpin or an intermolecular duplex. Slow conversion to the quadruplex in vitro (in a potassium-rich buffer) and cells was demonstrated by NMR. 'Shape-shifting' sequences may respond to [Na+]/[K+] changes with delayed kinetics.
Assuntos
Quadruplex G , Potássio , Sódio , Humanos , Espectroscopia de Ressonância Magnética , Mutação , Potássio/química , Sódio/químicaRESUMO
Hepatitis B virus (HBV) is one of the most dangerous human pathogenic viruses found in all corners of the world. Recent sequencing of ancient HBV viruses revealed that these viruses have accompanied humanity for several millenia. As G-quadruplexes are considered to be potential therapeutic targets in virology, we examined G-quadruplex-forming sequences (PQS) in modern and ancient HBV genomes. Our analyses showed the presence of PQS in all 232 tested HBV genomes, with a total number of 1258 motifs and an average frequency of 1.69 PQS per kbp. Notably, the PQS with the highest G4Hunter score in the reference genome is the most highly conserved. Interestingly, the density of PQS motifs is lower in ancient HBV genomes than in their modern counterparts (1.5 and 1.9/kb, respectively). This modern frequency of 1.90 is very close to the PQS frequency of the human genome (1.93) using identical parameters. This indicates that the PQS content in HBV increased over time to become closer to the PQS frequency in the human genome. No statistically significant differences were found between PQS densities in HBV lineages found in different continents. These results, which constitute the first paleogenomics analysis of G4 propensity, are in agreement with our hypothesis that, for viruses causing chronic infections, their PQS frequencies tend to converge evolutionarily with those of their hosts, as a kind of 'genetic camouflage' to both hijack host cell transcriptional regulatory systems and to avoid recognition as foreign material.
Assuntos
Quadruplex G , Vírus da Hepatite B , Humanos , Genoma Humano , Genômica , Vírus da Hepatite B/genética , Paleontologia , Evolução BiológicaRESUMO
Cytosine-rich DNA regions can form four-stranded structures based on hemi-protonated C.C+ pairs, called i-motifs (iMs). Using CD, UV absorption, NMR spectroscopy, and DSC calorimetry, we show that model (CnT3)3Cn (Cn) sequences adopt iM under neutral or slightly alkaline conditions for n > 3. However, the iMs are formed with long-lasting kinetics under these conditions and melt with significant hysteresis. Sequences with n > 6 melt in two or more separate steps, indicating the presence of different iM species, the proportion of which is dependent on temperature and incubation time. At ambient temperature, kinetically favored iMs of low stability are formed, most likely consisting of short C.C+ blocks. These species act as kinetic traps and prevent the assembly of thermodynamically favored, fully C.C+ paired iMs. A higher temperature is necessary to unfold the kinetic forms and enable their substitution by a slowly developing thermodynamic structure. This complicated kinetic partitioning process considerably slows down iM folding, making it much slower than the timeframes of biological reactions and, therefore, unlikely to have any biological relevance. Our data suggest kinetically driven iM species as more likely to be biologically relevant than thermodynamically most stable iM forms.
Assuntos
DNA , Conformação de Ácido Nucleico , Cinética , Motivos de Nucleotídeos , DNA/genética , DNA/química , Concentração de Íons de HidrogênioRESUMO
Biomimetic enzymes have emerged as ideal alternatives to natural enzymes, and there is considerable interest in designing biomimetic enzymes with enhanced catalytic performance to address the low activity of the current biomimetic enzymes. In this study, we proposed a meaningful strategy for constructing an efficient peroxidase-mimicking catalyst, called HhG-MOF, by anchoring histidine (H) and dual hemin-G-quadruplex DNAzyme (double hemin covalently linked to 3' and 5' terminals of G-quadruplex DNA, short as hG) to a mesoporous metal-organic framework (MOF). This design aims to mimic the microenvironment of natural peroxidase. Remarkably, taking a terbium MOF as a typical model, the initial rate of the resulting catalyst was found to be 21.1 and 4.3 times higher than that of Hh-MOF and hG-MOF, respectively. The exceptional catalytic properties of HhG-MOF can be attributed to its strong affinity for substrates. Based on the inhibitory effect of thiocholine (TCh) produced by the reaction between acetylcholinesterase (AChE) and acetylthiocholine, a facile, cost-effective, and sensitive colorimetric method was designed based on HhG-MOF for the measurement of AChE, a marker of several neurological diseases, and its inhibitor. This allowed a linear response in the 0.002 to 1 U L-1 range, with a detection limit of 0.001 U L-1. Furthermore, the prepared sensor demonstrated great selectivity and performed well in real blood samples, suggesting that it holds promise for applications in the clinical field.
RESUMO
Algorithms have been widely used to predict G-quadruplexes (G4s)-prone sequences. However, an experimental validation of these predictions is generally required. We previously reported a high-throughput technique to evidence G4 formation in vitro called FRET-MC. This method, while convenient and reproducible, has one known weakness: its inability to pin point G4 motifs of low thermal stability. As such quadruplexes may still be biologically relevant if formed at physiological temperature, we wanted to develop an independent assay to overcome this limitation. To this aim, we introduced an isothermal version of the competition assay, called iso-FRET, based on a duplex-quadruplex competition and a well-characterized bis-quinolinium G4 ligand, PhenDC3. G4-forming competitors act as decoys for PhenDC3, lowering its ability to stabilize the G4-forming motif reporter oligonucleotide conjugated to a fluorescence quencher (37Q). The decrease in available G4 ligand concentration restores the ability of 37Q to hybridize to its FAM-labeled short complementary C-rich strand (F22), leading to a decrease in fluorescence signal. In contrast, when no G4-forming competitor is present, PhenDC3 remains available to stabilize the 37Q quadruplex, preventing the formation of the F22 + 37Q complex. Iso-FRET was first applied to a reference panel of 70 sequences, and then used to investigate 23 different viral sequences.
Assuntos
Transferência Ressonante de Energia de Fluorescência , Quadruplex G , LigantesRESUMO
The Caenorhabditis elegans model has greatly contributed to the understanding of the role of G-quadruplexes in genomic instability. The GGCTTA repeats of the C. elegans telomeres resemble the GGGTTA repeats of the human telomeres. However, the comparison of telomeric sequences (Homo sapiens, Tetrahymena, Oxytricha, Bombyx mori and Giardia) revealed that small changes in these repeats can drastically change the topology of the folded G-quadruplex. In the present work we determined the structure adopted by the C. elegans telomeric sequence d[GG(CTTAGG)3]. The investigated C. elegans telomeric sequence is shown to fold into an intramolecular two G-tetrads basket type G-quadruplex structure that includes a C-T base pair in the diagonal loop. This work sheds light on the telomeric structure of the widely used C. elegans animal model.
Assuntos
Caenorhabditis elegans , Quadruplex G , Telômero , Animais , Humanos , Pareamento de Bases , Caenorhabditis elegans/genética , Telômero/químicaRESUMO
G-quadruplexes (G4s) are four-stranded nucleic acid structures formed by the stacking of G-tetrads. Here we investigated their formation and function during HIV-1 infection. Using bioinformatics and biophysics analyses we first searched for evolutionary conserved G4-forming sequences in HIV-1 genome. We identified 10 G4s with conservation rates higher than those of HIV-1 regulatory sequences such as RRE and TAR. We then used porphyrin-based G4-binders to probe the formation of the G4s during infection of human cells by native HIV-1. The G4-binders efficiently inhibited HIV-1 infectivity, which is attributed to the formation of G4 structures during HIV-1 replication. Using a qRT-PCR approach, we showed that the formation of viral G4s occurs during the first 2 h post-infection and their stabilization by the G4-binders prevents initiation of reverse transcription. We also used a G4-RNA pull-down approach, based on a G4-specific biotinylated probe, to allow the direct detection and identification of viral G4-RNA in infected cells. Most of the detected G4-RNAs contain crucial regulatory elements such as the PPT and cPPT sequences as well as the U3 region. Hence, these G4s would function in the early stages of infection when the viral RNA genome is being processed for the reverse transcription step.
Assuntos
Quadruplex G , HIV-1 , Humanos , RNA/química , HIV-1/genética , Sequências Reguladoras de Ácido Nucleico , Sequência ConservadaRESUMO
Parasitic helminths infecting humans are highly prevalent infecting â¼2 billion people worldwide, causing inflammatory responses, malnutrition and anemia that are the primary cause of morbidity. In addition, helminth infections of cattle have a significant economic impact on livestock production, milk yield and fertility. The etiological agents of helminth infections are mainly Nematodes (roundworms) and Platyhelminths (flatworms). G-quadruplexes (G4) are unusual nucleic acid structures formed by G-rich sequences that can be recognized by specific G4 ligands. Here we used the G4Hunter Web Tool to identify and compare potential G4 sequences (PQS) in the nuclear and mitochondrial genomes of various helminths to identify G4 ligand targets. PQS are nonrandomly distributed in these genomes and often located in the proximity of genes. Unexpectedly, a Nematode, Ascaris lumbricoides, was found to be highly enriched in stable PQS. This species can tolerate high-stability G4 structures, which are not counter selected at all, in stark contrast to most other species. We experimentally confirmed G4 formation for sequences found in four different parasitic helminths. Small molecules able to selectively recognize G4 were found to bind to Schistosoma mansoni G4 motifs. Two of these ligands demonstrated potent activity both against larval and adult stages of this parasite.
Assuntos
Quadruplex G , Nematoides , Parasitos/genética , Platelmintos , Animais , Bovinos , Genoma , Helmintos/genética , Humanos , Ligantes , Nematoides/genética , Platelmintos/genéticaRESUMO
Guanine-rich DNA and RNA sequences can fold into noncanonical nucleic acid structures called G-quadruplexes (G4s). Since the discovery that these structures may act as scaffolds for the binding of specific ligands, G4s aroused the attention of a growing number of scientists. The versatile roles of G4 structures in viral replication, transcription, and translation suggest direct applications in therapy or diagnostics. G4-interacting molecules (proteins or small molecules) may also affect the balance between latent and lytic phases, and increasing evidence reveals that G4s are implicated in generally suppressing viral processes, such as replication, transcription, translation, or reverse transcription. In this review, we focus on the discovery of G4s in viruses and the role of G4 ligands in the antiviral drug discovery process. After assessing the role of viral G4s, we argue that host G4s participate in immune modulation, viral tumorigenesis, cellular pathways involved in virus maturation, and DNA integration of viral genomes, which can be potentially employed for antiviral therapeutics. Furthermore, we scrutinize the impediments and shortcomings in the process of studying G4 ligands and drug discovery. Finally, some unanswered questions regarding viral G4s are highlighted for prospective future projects. SIGNIFICANCE STATEMENT: G-quadruplexes (G4s) are noncanonical nucleic acid structures that have gained increasing recognition during the last few decades. First identified as relevant targets in oncology, their importance in virology is now increasingly clear. A number of G-quadruplex ligands are known: viral transcription and replication are the main targets of these ligands. Both viral and cellular G4s may be targeted; this review embraces the different aspects of G-quadruplexes in both host and viral contexts.
Assuntos
Quadruplex G , Antivirais/farmacologia , Humanos , Ligantes , Estudos ProspectivosRESUMO
DNA quadruplex structures provide an additional layer of regulatory control in genome maintenance and gene expression and are widely used in nanotechnology. We report the discovery of an unprecedented tetrastranded structure formed from a native G-rich DNA sequence originating from the telomeric region of Caenorhabditis elegans. The structure is defined by multiple properties that distinguish it from all other known DNA quadruplexes. Most notably, the formation of a stable so-called KNa-quadruplex (KNaQ) requires concurrent coordination of K+ and Na+ ions at two distinct binding sites. This structure provides novel insight into G-rich DNA folding under ionic conditions relevant to eukaryotic cell physiology and the structural evolution of telomeric DNA. It highlights the differences between the structural organization of human and nematode telomeric DNA, which should be considered when using C. elegans as a model in telomere biology, particularly in drug screening applications. Additionally, the absence/presence of KNaQ motifs in the host/parasite introduces an intriguing possibility of exploiting the KNaQ fold as a plausible antiparasitic drug target. The structure's unique shape and ion dependency and the possibility of controlling its folding by using low-molecular-weight ligands can be used for the design or discovery of novel recognition DNA elements and sensors.
Assuntos
Quadruplex G , Animais , Humanos , Caenorhabditis elegans/genética , DNA/química , Sequência de Bases , Cátions , Telômero/genéticaRESUMO
Chimeric peptide-DNAzyme (CPDzyme) is a novel artificial peroxidase that relies on the covalent assembly of DNA, peptides, and an enzyme cofactor in a single scaffold. An accurate control of the assembly of these different partners allows for the design of the CPDzyme prototype G4-Hemin-KHRRH, found to be >2000-fold more active (in terms of conversion number kcat) than the corresponding but non-covalent G4/Hemin complex and, more importantly, >1.5-fold more active than the corresponding native peroxidase (horseradish peroxidase) when considering a single catalytic center. This unique performance originates in a series of gradual improvements, thanks to an accurate selection and arrangement of the different components of the CPDzyme, in order to benefit from synergistic interactions between them. The optimized prototype G4-Hemin-KHRRH is efficient and robust as it can be used under a wide range of non-physiologically relevant conditions [organic solvents, high temperature (95 °C), and in a wide range of pH (from 2 to 10)], thus compensating for the shortcomings of the natural enzymes. Our approach thus opens broad prospects for the design of ever more efficient artificial enzymes.
Assuntos
DNA Catalítico , Quadruplex G , Peroxidase do Rábano Silvestre/metabolismo , Hemina , Peroxidase/metabolismo , Peroxidases , DNA Catalítico/metabolismo , PeptídeosRESUMO
BACKGROUND: Once integrated in the genome of infected cells, HIV-1 provirus is transcribed by the cellular transcription machinery. This process is regulated by both viral and cellular factors, which are necessary for an efficient viral replication as well as for the setting up of viral latency, leading to a repressed transcription of the integrated provirus. RESULTS: In this study, we examined the role of two parameters in HIV-1 LTR promoter activity. We identified DNA topoisomerase1 (TOP1) to be a potent repressor of this promoter and linked this repression to its catalytic domain. Additionally, we confirmed the folding of a Guanine quadruplex (G4) structure in the HIV-1 promoter and its repressive effect. We demonstrated a direct interaction between TOP1 and this G4 structure, providing evidence of a functional relationship between the two repressive elements. Mutations abolishing G4 folding affected TOP1/G4 interaction and hindered G4-dependent inhibition of TOP1 catalytic activity in vitro. As a result, HIV-1 promoter activity was reactivated in a native chromatin environment. Lastly, we noticed an enrichment of predicted G4 sequences in the promoter of TOP1-repressed cellular genes. CONCLUSIONS: Our results demonstrate the formation of a TOP1/G4 complex on the HIV-1 LTR promoter and its repressive effect on the promoter activity. They reveal the existence of a new mechanism of TOP1/G4-dependent transcriptional repression conserved between viral and human genes. This mechanism contrasts with the known property of TOP1 as global transcriptional activator and offers new perspectives for anti-cancer and anti-viral strategies.
Assuntos
HIV-1 , Humanos , HIV-1/genética , Guanina , Fatores de Transcrição/genética , Cromatina , Repetição Terminal Longa de HIV/genética , Transcrição GênicaRESUMO
Genomic sequences susceptible to form G-quadruplexes (G4s) are always flanked by other nucleotides, but G4 formation in vitro is generally studied with short synthetic DNA or RNA oligonucleotides, for which bases adjacent to the G4 core are often omitted. Herein, we systematically studied the effects of flanking nucleotides on structural polymorphism of 371 different oligodeoxynucleotides that adopt intramolecular G4 structures. We found out that the addition of nucleotides favors the formation of a parallel fold, defined as the 'flanking effect' in this work. This 'flanking effect' was more pronounced when nucleotides were added at the 5'-end, and depended on loop arrangement. NMR experiments and molecular dynamics simulations revealed that flanking sequences at the 5'-end abolish a strong syn-specific hydrogen bond commonly found in non-parallel conformations, thus favoring a parallel topology. These analyses pave a new way for more accurate prediction of DNA G4 folding in a physiological context.
Assuntos
Quadruplex G , Nucleotídeos/genética , Oligonucleotídeos/genética , Polimorfismo Genético/genética , Dicroísmo Circular , DNA/genética , DNA/ultraestrutura , Ligação de Hidrogênio , Simulação de Dinâmica Molecular , Conformação de Ácido Nucleico , Nucleotídeos/química , Oligonucleotídeos/química , RNA/genética , RNA/ultraestruturaRESUMO
The multidomain non-structural protein 3 (Nsp3) is the largest protein encoded by coronavirus (CoV) genomes and several regions of this protein are essential for viral replication. Of note, SARS-CoV Nsp3 contains a SARS-Unique Domain (SUD), which can bind Guanine-rich non-canonical nucleic acid structures called G-quadruplexes (G4) and is essential for SARS-CoV replication. We show herein that the SARS-CoV-2 Nsp3 protein also contains a SUD domain that interacts with G4s. Indeed, interactions between SUD proteins and both DNA and RNA G4s were evidenced by G4 pull-down, Surface Plasmon Resonance and Homogenous Time Resolved Fluorescence. These interactions can be disrupted by mutations that prevent oligonucleotides from folding into G4 structures and, interestingly, by molecules known as specific ligands of these G4s. Structural models for these interactions are proposed and reveal significant differences with the crystallographic and modeled 3D structures of the SARS-CoV SUD-NM/G4 interaction. Altogether, our results pave the way for further studies on the role of SUD/G4 interactions during SARS-CoV-2 replication and the use of inhibitors of these interactions as potential antiviral compounds.
Assuntos
COVID-19/virologia , Proteases Semelhantes à Papaína de Coronavírus/metabolismo , Quadruplex G , Domínios e Motivos de Interação entre Proteínas , SARS-CoV-2 , Sequência de Aminoácidos , Proteases Semelhantes à Papaína de Coronavírus/química , Humanos , Ligantes , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Análise Espectral , Relação Estrutura-Atividade , Replicação ViralRESUMO
Mechanisms of transcriptional control in malaria parasites are still not fully understood. The positioning patterns of G-quadruplex (G4) DNA motifs in the parasite's AT-rich genome, especially within the var gene family which encodes virulence factors, and in the vicinity of recombination hotspots, points towards a possible regulatory role of G4 in gene expression and genome stability. Here, we carried out the most comprehensive genome-wide survey, to date, of G4s in the Plasmodium falciparum genome using G4Hunter, which identifies G4 forming sequences (G4FS) considering their G-richness and G-skewness. We show an enrichment of G4FS in nucleosome-depleted regions and in the first exon of var genes, a pattern that is conserved within the closely related Laverania Plasmodium parasites. Under G4-stabilizing conditions, i.e., following treatment with pyridostatin (a high affinity G4 ligand), we show that a bona fide G4 found in the non-coding strand of var promoters modulates reporter gene expression. Furthermore, transcriptional profiling of pyridostatin-treated parasites, shows large scale perturbations, with deregulation affecting for instance the ApiAP2 family of transcription factors and genes involved in ribosome biogenesis. Overall, our study highlights G4s as important DNA secondary structures with a role in Plasmodium gene expression regulation, sub-telomeric recombination and var gene biology.
Assuntos
Quadruplex G , Malária/genética , Motivos de Nucleotídeos/genética , Plasmodium falciparum/genética , Aminoquinolinas/farmacologia , Animais , Regulação da Expressão Gênica/efeitos dos fármacos , Genoma/efeitos dos fármacos , Humanos , Malária/tratamento farmacológico , Malária/parasitologia , Ácidos Picolínicos/farmacologia , Plasmodium falciparum/patogenicidade , Regiões Promotoras Genéticas/genética , Ribossomos/efeitos dos fármacos , Ribossomos/genéticaRESUMO
G-quadruplex/hemin (G4/hemin) DNAzymes are biosensing systems, but their application remains limited by an overall low activity and a rather high level of unwarranted background reactions. Here, these issues were addressed through the rational design of F3T-azaC-hemin, a G4-based construct in which the hemin is covalently linked to the G4 core and its binding site flanked with a nucleotide activator, here d(T-azaC). This design led to a G4-DNAzyme whose performances have been ca. 150-fold increased compared to the parent G4-based system. The utility of F3T-azaC-hemin was demonstrated here through the ultrasensitive chemiluminescent detection of miRNA-221. The limit of detection (LOD) has been decreased to the femtomolar range, making it a new and highly efficient molecular tool in the biosensing technology field.
Assuntos
Técnicas Biossensoriais , DNA Catalítico , Quadruplex G , Catálise , DNA Catalítico/química , Hemina/química , Peróxido de Hidrogênio/químicaRESUMO
A high catalytic efficiency associated with a robust chemical structure are among the ultimate goals when developing new biocatalytic systems for biosensing applications. To get ever closer to these goals, we report here on a combination of metal-organic framework (MOF)-based nanozymes and a G-quadruplex (G4)-based catalytic system known as G4-DNAzyme. This approach aims at combining the advantages of both partners (chiefly, the robustness of the former and the modularity of the latter). To this end, we used MIL-53(Fe) MOF and linked it covalently to a G4-forming sequence (F3TC), itself covalently linked to its cofactor hemin. The resulting complex (referred to as MIL-53(Fe)/G4-hemin) exhibited exquisite peroxidase-mimicking oxidation activity and an excellent robustness (being stored in water for weeks). These properties were exploited to devise a new biosensing system based on a cascade of reactions catalyzed by the nanozyme (ABTS oxidation) and an enzyme, the alkaline phosphatase (or ALP, ascorbic acid 2-phosphate dephosphorylation). The product of the latter poisoning the former, we thus designed a biosensor for ALP (a marker of bone diseases and cancers), with a very low limit of detection (LOD, 0.02 U L-1), which is operative in human plasma samples.
Assuntos
Técnicas Biossensoriais , DNA Catalítico , Quadruplex G , Estruturas Metalorgânicas , Técnicas Biossensoriais/métodos , DNA Catalítico/química , Hemina/química , Humanos , Estruturas Metalorgânicas/químicaRESUMO
The long-standing history of platinum coordination complexes in nucleic acid recognition attests to the unique suitability of such species for therapeutic applications. Here, we report the synthetic exploration and development of a family of di-imine ligands, and their platinum(II) complexes, elaborated on a 3-(2-pyridyl)-[1,2,4]triazolo[4,3-a]pyridine platform which, in its unsubstituted form, has recently been shown to display exceptional capabilities for guanine quadruplex (G4) targeting. The identification of facile, high-yielding synthetic methods for the derivatization of this platform for the incorporation of additional sites of interactions with guanine quadruplex loops and grooves, along with the optimization of platinum(II) complexation methods, are discussed. Gratifyingly, preliminary biophysical screening of this novel family of binders validates all but one family members as robust G4 binders and highlights enhanced selectivity for quadruplex versus duplex DNA compared to the parent compound. These results bear promise for practical developments based on this platform.