RESUMO
Colorectal cancer (CRC) remains a significant global health concern, necessitating continuous investigation into its etiology and potential risk factors. Recent research has shed light on the potential role of pKs-positive Escherichia coli (pKs + E. coli) and colibactin in the development and progression of CRC. Therefore, this review aimed to provide an updated analysis of the prevalence and implications of pKs + E. coli in colorectal cancer. We conducted a literature review search in major scientific databases to identify relevant studies exploring the association between pKs + E. coli and CRC. The search strategy included studies published up to the present date, and articles were carefully selected based on predefined inclusion criteria. Thus, the present study encompasses scientific evidence from clinical and epidemiological studies supporting the presence of pKs + E. coli in CRC patients, demonstrating a consistent and significant association in multiple studies. Furthermore, we highlighted the potential mechanisms by which colibactin may promote tumorigenesis and cancer progression within the colorectal mucosa, including the production of genotoxic virulence factors. Additionally, we explored current diagnostic methods for detecting pKs + E. coli in clinical settings, emphasizing the importance of accurate identification. Moreover, we discussed future strategies that could utilize the presence of this strain as a biomarker for CRC diagnosis and treatment. In conclusion, this review consolidated existing evidence on the prevalence and implications of pKs + E. coli in colorectal cancer. The findings underscore the importance of further research to elucidate the precise mechanisms linking this strain to CRC pathogenesis and to explore its potential as a therapeutic target or diagnostic marker. Ultimately, a better understanding of the role of pKs + E. coli in CRC may pave the way for innovative strategies in CRC management and patient care.
Assuntos
Neoplasias Colorretais , Escherichia coli , Policetídeos , Humanos , Prevalência , Peptídeos , Neoplasias Colorretais/epidemiologiaRESUMO
Bioassay-guided investigation of the EtOAc-soluble extract of a culture of the marine-derived fungus Peroneutypa sp. M16 led to the isolation of seven new polyketide- and terpenoid-derived metabolites (1, 2, 4-8), along with known polyketides (3, 9-13). Structures of compounds 1, 2, and 4-8 were established by analysis of spectroscopic data. Absolute configurations of compounds 1, 2, 4, 6, 7, and 8 were determined by the comparison of experimental ECD spectra with calculated CD data. Compound 5 exhibited moderate antiplasmodial activity against both chloroquine-sensitive and -resistant strains of Plasmodium falciparum.
Assuntos
Policetídeos , Xylariales , Policetídeos/química , Terpenos/química , Estrutura Molecular , Extratos VegetaisRESUMO
As part of our continuing efforts to discover new bioactive compounds from endophytic fungal sources, we have investigated the extract of the Paraphaeosphaeria sporulosa F03 strain. The study led to the isolation of four new 3-methyl-isoquinoline alkaloids (1: â-â4: ) and four known polyketides (5: â-â8: ). The structures of compounds 1: â-â4: were elucidated by 1D and 2D NMR experiments and HRMS analysis. The absolute configuration of 4: was determined by comparison of its experimental electronic circular dichroism spectrum with calculated data. Compounds 1: â-â4: exhibited antifungal activity with minimal inhibitory concentration values ranging from 6.25â-â50 µg/mL against six Candida species but they did not present any cytotoxic activity against the human tumor cell lines A549 (lung), MCF-7 (breast), and HepG2 (hepatocellular). In addition, compound 4: exhibited antiplasmodial activity in the low micromolar range (IC50 = 4 µM).
Assuntos
Alcaloides , Antimaláricos , Eriocaulaceae , Policetídeos , Antifúngicos/farmacologia , Antimaláricos/farmacologia , Ascomicetos , Endófitos/química , Humanos , Isoquinolinas/química , Isoquinolinas/farmacologia , Estrutura Molecular , Extratos Vegetais , Policetídeos/química , Policetídeos/farmacologiaRESUMO
BACKGROUND: The N-terminal domain of Tetracenomycin aromatase/cyclase (TcmN), an enzyme derived from Streptomyces glaucescens, is involved in polyketide cyclization, aromatization, and folding. Polyketides are a diverse class of secondary metabolites produced by certain groups of bacteria, fungi, and plants with various pharmaceutical applications. Examples include antibiotics, such as tetracycline, and anticancer drugs, such as doxorubicin. Because TcmN is a promising enzyme for in vitro production of polyketides, it is important to identify conditions that enhance its thermal resistance and optimize its function. METHODS: TcmN unfolding, stability, and dynamics were evaluated by fluorescence spectroscopy, circular dichroism, nuclear magnetic resonance 15N relaxation experiments, and microsecond molecular dynamics (MD) simulations. RESULTS: TcmN thermal resistance was enhanced at low protein and high salt concentrations, was pH-dependent, and denaturation was irreversible. Conformational dynamics on the µs-ms timescale were detected for residues in the substrate-binding cavity, and two predominant conformers representing opened and closed cavity states were observed in the MD simulations. CONCLUSION: Based on the results, a mechanism was proposed in which the thermodynamics and kinetics of the TcmN conformational equilibrium modulate enzyme function by favoring ligand binding and avoiding aggregation. GENERAL SIGNIFICANCE: Understanding the principles underlying TcmN stability and dynamics may help in designing mutants with optimal properties for biotechnological applications.
Assuntos
Proteínas de Bactérias/metabolismo , Complexos Multienzimáticos/metabolismo , Policetídeos/metabolismo , Streptomyces/enzimologia , Proteínas de Bactérias/química , Sítios de Ligação , Modelos Moleculares , Estrutura Molecular , Complexos Multienzimáticos/química , Policetídeos/química , Agregados ProteicosRESUMO
In recent years, the fermented milk product kefir has been intensively studied because of its health benefits. Here, we evaluated the microbial consortia of two kefir samples, from Escarcega, Campeche, and Campeche (México). We considered a functional comparison between both samples, including fungal and bacterial inhibition; second, we applied shotgun metagenomics to assess the structure and functional diversity of the communities of microorganisms. These two samples exhibited antagonisms against bacterial and fungal pathogens. Bioactive polyketides and nonribosomal peptides were identified by LC-HRMS analysis. We also observed a high bacterial diversity and an abundance of Actinobacteria in both kefir samples, and a greater abundance of Saccharomyces species in kefir of Escarcega than in the Campeche kefir. When the prophage compositions were evaluated, the Campeche sample showed a higher diversity of prophage sequences. In Escarcega, we observed a prevalence of prophage families that infect Enterobacteria and Lactobacillus. The sequences associated with secondary metabolites, such as plipastatin, fengycin, and bacillaene, and also bacteriocins like helveticin and zoocin, were also found in different proportions, with greater diversity in the Escarcega sample. The analyses described in this work open the opportunity to understand the microbial diversity in kefir samples from two distant localities.
Assuntos
Anti-Infecciosos/metabolismo , Anti-Infecciosos/farmacologia , Bactérias/efeitos dos fármacos , Fungos/efeitos dos fármacos , Kefir/microbiologia , Metagenoma , Animais , Bactérias/classificação , Biodiversidade , Produtos Fermentados do Leite/microbiologia , DNA Bacteriano , DNA Fúngico , Fermentação , Microbiologia de Alimentos , Fungos/classificação , Metagenômica/métodos , México , Microbiota , Leite/microbiologia , Peptídeos/farmacologia , Policetídeos/farmacologia , Prófagos/genética , Metabolismo SecundárioRESUMO
A fast PCR-assisted impedimetric biosensor was developed for the selective detection of the clbN gene from the polyketide synthase (pks) genomic island in real Escherichia coli samples. This genomic island is responsible for the production of colibactin, a harmful genotoxin that has been associated with colorectal cancer. The experimental protocol consisted of immobilizing the designated forward primer onto an Au electrode surface to create the sensing probe, followed by PCR temperature cycling in blank, positive, and negative DNA controls. Target DNA identification was possible by monitoring changes in the system's charge transfer resistance values (Rct) before and after PCR treatment through electrochemical impedance spectroscopy (EIS) analysis. Custom-made, flexible gold electrodes were fabricated using chemical etching optical lithography. A PCR cycle study determined the optimum conditions to be at 6 cycles providing fast results while maintaining a good sensitivity. EIS data for the DNA recognition process demonstrated the successful distinction between target interaction resulting in an increase in resistance to charge transfer (Rct) percentage change of 176% for the positive DNA control vs. 21% and 20% for the negative and non-DNA-containing controls, respectively. Results showed effective fabrication of a fast, PCR-based electrochemical biosensor for the detection of pks genomic island with a calculated limit of detection of 17 ng/µL.
Assuntos
Técnicas Biossensoriais/métodos , Espectroscopia Dielétrica/métodos , Escherichia coli/genética , Genoma Bacteriano , Peptídeos/genética , Policetídeo Sintases/genética , Reação em Cadeia da Polimerase/métodos , Limite de Detecção , PolicetídeosRESUMO
Plocabulin is a novel microtubule (MT) destabilizer agent with potent antineoplastic activity. This compound binds to the maytansine site at the longitudinal interface between tubulin dimers and exerts a hinge-like effect that disrupts normal microtubule assembly. Plocabulin has emerged as a valuable model for the rational design of novel MT destabilizers because of its unique structural and mechanistic features. To make progress on this matter, detailed molecular-level understanding of the ligand-protein interactions responsible for plocabulin association and the conformation and energetic effects arising from plocabulin binding on the longitudinal interaction between tubulin dimers must be provided. In this work, fully atomistic MD simulations and MM/GBSA binding free-energy calculations were used to examine the association of plocabulin to one or two tubulin dimers in longitudinal arrangement. Our results revealed that plocabulin binding is favored by the addition of a second tubulin dimer and that this ligand promotes the assembly of curved tetrameric arrangements with strengthened longitudinal interdimeric interactions compared to ligand-free systems. The applicability of these findings to the rational discovery of novel MT destabilizers was tested using MD and MM/GBSA calculations as filtering tools to narrow the results of virtual screening among an FDA-approved drug database. Our results confirmed that tight-binding ligands do not necessarily exert the expected conformational and energetic effects on longitudinal tubulin-tubulin interactions, which is a matter to consider in future design strategies.
Assuntos
Policetídeos , Tubulina (Proteína) , Microtúbulos , PironasRESUMO
Alpiniamide A is a linear polyketide produced by Streptomyces endophytic bacteria. Despite its relatively simple chemical structure suggestive of a linear assembly line biosynthetic construction involving a hybrid polyketide synthase-nonribosomal peptide synthetase enzymatic protein machine, we report an unexpected nonlinear synthesis of this bacterial natural product. Using a combination of genomics, heterologous expression, mutagenesis, isotope-labeling, and chain terminator experiments, we propose that alpiniamide A is assembled in two halves and then ligated into the mature molecule. We show that each polyketide half is constructed using orthogonal biosynthetic strategies, employing either cis- or trans-acyl transferase mechanisms, thus prompting an alternative proposal for the operation of this PKS-NRPS.