ABSTRACT
Desert strains of the genus Chroococcidiopsis are among the most desiccation-resistant cyanobacteria capable of anhydrobiosis. The accumulation of two sugars, sucrose and trehalose, facilitates the entrance of anhydrobiotes into a reversible state of dormancy by stabilizing cellular components upon water removal. This study aimed to evaluate, at the atomistic level, the role of trehalose in desiccation resistance by using as a model system the 30S ribosomal subunit of the desert cyanobacterium Chroococcidiopsis sp. 029. Molecular dynamic simulations provided atomistic evidence regarding its protective role on the 30S molecular structure. Trehalose forms an enveloping shell around the ribosomal subunit and stabilizes the structures through a network of direct interactions. The simulation confirmed that trehalose actively interacts with the 30S ribosomal subunit and that, by replacing water molecules, it ensures ribosomal structural integrity during desiccation, thus enabling protein synthesis to be carried out upon rehydration.
Subject(s)
Cyanobacteria , Molecular Dynamics Simulation , Trehalose , Trehalose/metabolism , Trehalose/chemistry , Cyanobacteria/metabolism , Cyanobacteria/chemistry , Ribosome Subunits, Small, Bacterial/metabolism , Ribosome Subunits, Small, Bacterial/chemistry , Desiccation , Models, MolecularABSTRACT
Cyanobacteriochromes (CBCRs) are unique cyanobacteria-specific photoreceptors that share a distant relation with phytochromes. Most CBCRs contain conserved cysteine residues known as canonical Cys, while some CBCRs have additional cysteine residues called second Cys within the DXCF motif, leading to their classification as DXCF CBCRs. They typically undergo a process where they incorporate phycocyanobilin (PCB) and subsequently isomerize it to phycoviolobilin (PVB). Conversely, CBCRs with conserved Trp residues and without the second Cys are called extended red/green (XRG) CBCRs. Typical XRG CBCRs bind PCB without undergoing PCB-to-PVB isomerization, displaying red/green reversible photoconversion, and there are also atypical CBCRs that exhibit diverse photoconversions. We discovered novel XRG CBCRs with Cys residue instead of the conserved Trp residue. These novel XRG CBCRs exhibited the ability to isomerize PCB to PVB, displaying green/teal reversible photoconversion. Through sequence- and structure-based comparisons coupled with mutagenesis experiments, we identified three amino acid residues, including the Cys residue, crucial for facilitating PCB-to-PVB isomerization. This research expands our understanding of the diversity of XRG CBCRs, highlighting the remarkable molecular plasticity of CBCRs.
Subject(s)
Bacterial Proteins , Cyanobacteria , Phycobilins , Phycocyanin , Phycobilins/chemistry , Phycobilins/metabolism , Phycocyanin/chemistry , Phycocyanin/metabolism , Cyanobacteria/metabolism , Cyanobacteria/chemistry , Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Bacterial Proteins/genetics , Isomerism , Photoreceptors, Microbial/chemistry , Photoreceptors, Microbial/metabolism , Photoreceptors, Microbial/geneticsABSTRACT
In our continuing search for biologically active new chemical entities from marine organisms, we have isolated a new cyclic depsipeptide, PM170453 (1), from a cyanobacterium of the genus Lyngbya sp., collected in the Indo-Pacific Ocean. Structure elucidation of the isolated compound was determined by spectroscopic methods including MS, 1H, 13C and 2D-NMR. To solve the supply problem for 1 and progress pharmaceutical development, the total synthesis of 1 that involves a total of 20 chemical steps in a convergent process was carried out. Its in vitro cytotoxic activity against four human tumor cell lines, as well as the inhibition of the interaction between the programmed cell death protein 1 PD-1 and its ligand PD-L1 were also evaluated.
Subject(s)
Antineoplastic Agents , Cyanobacteria , Depsipeptides , Depsipeptides/pharmacology , Depsipeptides/isolation & purification , Depsipeptides/chemistry , Depsipeptides/chemical synthesis , Humans , Cyanobacteria/chemistry , Cell Line, Tumor , Antineoplastic Agents/pharmacology , Antineoplastic Agents/isolation & purification , Antineoplastic Agents/chemistry , Antineoplastic Agents/chemical synthesis , Aquatic Organisms , B7-H1 Antigen/antagonists & inhibitors , Pacific Ocean , Peptides, Cyclic/pharmacology , Peptides, Cyclic/chemistry , Peptides, Cyclic/isolation & purificationABSTRACT
The physiological parameters such as growth, Chl a content, and photosynthetic performance of the experimental cyanobacterium Anabaenopsis circularis HKAR-22 were estimated to evaluate the cumulative effects of photosynthetically active radiation (PAR) and ultraviolet (UV) radiation. Maximum induction of UV-screening molecules, MAAs, was observed under the treatment condition of PAR + UV-A + UV-B (PAB) radiations. UV/VIS absorption spectroscopy and HPLC-PDA detection primarily confirmed the presence of MAA-shinorine (SN) having absorption maxima (λmax) at 332.3 nm and retention time (RT) of 1.47 min. For further validation of the presence of SN, HRMS, FTIR and NMR were utilized. UV-stress elevated the in vivo ROS scavenging and in vitro enzymatic antioxidant capabilities. SN exhibited substantial and concentration-dependent antioxidant capabilities which was determined utilizing 2,2-diphenyl-1-picryl-hydrazyl (DPPH), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate (ABTS), ferric reducing power (FRAP) and superoxide radical scavenging assay (SRSA). The density functional theory (DFT) method using B3LYP energy model and 6-311G++(d,p) basis set was implied to perform the quantum chemical calculation to systematically investigate the antioxidant nature of SN. The principal pathways involved in the antioxidant reactions along with the basic molecular descriptors affecting the antioxidant potentials of a compound were also studied. The results favor the potential of SN as an active ingredient to be used in cosmeceutical formulations.
Subject(s)
Antioxidants , Cyanobacteria , Density Functional Theory , Ultraviolet Rays , Antioxidants/chemistry , Cyanobacteria/chemistry , Cyanobacteria/metabolism , Amino Acids/chemistry , Amino Acids/metabolism , Cyclohexanones/chemistry , Photosynthesis , Reactive Oxygen Species/metabolism , Chlorophyll A/chemistry , Chlorophyll A/metabolism , Biphenyl Compounds/chemistry , Picrates/antagonists & inhibitors , Picrates/chemistry , Free Radical Scavengers/chemistry , Cyclohexylamines , Glycine/analogs & derivatives , Sulfonic Acids , BenzothiazolesABSTRACT
Microalgae are a source of a wide variety of commodities, including particularly valuable pigments. The typical pigments present in microalgae are the chlorophylls, carotenoids, and phycobiliproteins. However, other types of pigments, of the family of water-soluble polyphenols, usually encountered in terrestrial plants, have been recently reported in microalgae. Among such microalgal polyphenols, many flavonoids have a yellowish hue, and are used as natural textile dyes. Besides being used as natural colorants, for example in the food or cosmetic industry, microalgal pigments also possess many bioactive properties, making them functional as nutraceutical or pharmaceutical agents. Each type of pigment, with its own chemical structure, fulfills particular biological functions. Considering both eukaryotes and prokaryotes, some species within the four most promising microalgae groups (Cyanobacteria, Rhodophyta, Chlorophyta and Heterokontophyta) are distinguished by their high contents of specific added-value pigments. To further enhance microalgae pigment contents during autotrophic cultivation, a review is made of the main related strategies adopted during the last decade, including light adjustments (quantity and quality, and the duration of the photoperiod cycle), and regard to mineral medium characteristics (salinity, nutrients concentrations, presence of inductive chemicals). In contrast to what is usually observed for growth-related pigments, accumulation of non-photosynthetic pigments (polyphenols and secondary carotenoids) requires particularly stressful conditions. Finally, pigment enrichment is also made possible with two new cutting-edge technologies, via the application of metallic nanoparticles or magnetic fields.
Subject(s)
Microalgae , Pigments, Biological , Microalgae/metabolism , Microalgae/chemistry , Pigments, Biological/chemistry , Carotenoids/chemistry , Carotenoids/metabolism , Carotenoids/analysis , Phycobiliproteins/chemistry , Phycobiliproteins/metabolism , Cyanobacteria/metabolism , Cyanobacteria/chemistry , Rhodophyta/chemistry , Rhodophyta/metabolism , Chlorophyta/chemistry , Chlorophyta/metabolism , Chlorophyll/analysis , Polyphenols/analysis , Polyphenols/chemistry , Polyphenols/metabolism , Culture Media/chemistryABSTRACT
Cyanobacteria were the first microorganisms that released oxygen into the atmosphere billions of years ago. To do it safely under intense sunlight, they developed strategies that prevent photooxidation in the photosynthetic membrane, by regulating the light-harvesting activity of their antenna complexes-the phycobilisomes-via the orange-carotenoid protein (OCP). This water-soluble protein interacts with the phycobilisomes and triggers nonphotochemical quenching (NPQ), a mechanism that safely dissipates overexcitation in the membrane. To date, the mechanism of action of OCP in performing NPQ is unknown. In this work, we performed ultrafast spectroscopy on a minimal NPQ system composed of the active domain of OCP bound to the phycobilisome core. The use of this system allowed us to disentangle the signal of the carotenoid from that of the bilins. Our results demonstrate that the binding to the phycobilisomes modifies the structure of the ketocarotenoid associated with OCP. We show that this molecular switch activates NPQ, by enabling excitation-energy transfer from the antenna pigments to the ketocarotenoid.
Subject(s)
Bacterial Proteins , Carotenoids , Cyanobacteria , Phycobilisomes , Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Carotenoids/chemistry , Carotenoids/metabolism , Cyanobacteria/metabolism , Cyanobacteria/chemistry , Phycobilisomes/chemistry , Phycobilisomes/metabolism , Bile Pigments/chemistry , Bile Pigments/metabolism , Photochemical ProcessesABSTRACT
Here, we report wajeepeptin (1), a new cyclic depsipeptide isolated from a marine Moorena sp. cyanobacterium. The structure was elucidated by a combination of spectroscopic analyses, X-ray diffraction analysis, and degradation reactions. Wajeepeptin (1) showed moderate cytotoxicity (IC50 = 3.7 µM against HeLa cells) and potent antitrypanosomal activity (IC50 = 0.73 ± 0.14 µM against Trypanosoma brucei rhodesiense).
Subject(s)
Cyanobacteria , Depsipeptides , Depsipeptides/pharmacology , Depsipeptides/chemistry , Depsipeptides/isolation & purification , Humans , Molecular Structure , HeLa Cells , Cyanobacteria/chemistry , Trypanosoma brucei rhodesiense/drug effects , Marine Biology , Trypanocidal Agents/pharmacology , Trypanocidal Agents/chemistry , Drug Screening Assays, Antitumor , Crystallography, X-Ray , Nuclear Magnetic Resonance, BiomolecularABSTRACT
Metals are important cofactors in the metabolic processes of cyanobacteria, including photosynthesis, cellular respiration, DNA replication, and the biosynthesis of primary and secondary metabolites. In adaptation to the marine environment, cyanobacteria use metallophores to acquire trace metals when necessary as well as to reduce potential toxicity from excessive metal concentrations. Leptochelins A-C were identified as structurally novel metallophores from three geographically dispersed cyanobacteria of the genus Leptothoe. Determination of the complex structures of these metabolites presented numerous challenges, but they were ultimately solved using integrated data from NMR, mass spectrometry and deductions from the biosynthetic gene cluster. The leptochelins are comprised of halogenated linear NRPS-PKS hybrid products with multiple heterocycles that have potential for hexadentate and tetradentate coordination with metal ions. The genomes of the three leptochelin producers were sequenced, and retrobiosynthetic analysis revealed one candidate biosynthetic gene cluster (BGC) consistent with the structure of leptochelin. The putative BGC is highly homologous in all three Leptothoe strains, and all possess genetic signatures associated with metallophores. Postcolumn infusion of metals using an LC-MS metabolomics workflow performed with leptochelins A and B revealed promiscuous binding of iron, copper, cobalt, and zinc, with greatest preference for copper. Iron depletion and copper toxicity experiments support the hypothesis that leptochelin metallophores may play key ecological roles in iron acquisition and in copper detoxification. In addition, the leptochelins possess significant cytotoxicity against several cancer cell lines.
Subject(s)
Cyanobacteria , Cyanobacteria/metabolism , Cyanobacteria/chemistry , Cyanobacteria/genetics , Humans , Multigene Family , Cell Line, Tumor , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Antineoplastic Agents/metabolismABSTRACT
Kavaratamide A (1), a new linear lipodepsipeptide possessing an unusual isopropyl-O-methylpyrrolinone moiety, was discovered from the tropical marine filamentous cyanobacterium Moorena bouillonii collected from Kavaratti, India. A comparative chemogeographic analysis of M. bouillonii collected from six different geographical regions led to the prioritized isolation of this metabolite from India as distinctive among our data sets. AI-based structure annotation tools, including SMART 2.1 and DeepSAT, accelerated the structure elucidation by providing useful structural clues, and the full planar structure was elucidated based on comprehensive HRMS, MS/MS fragmentation, and NMR data interpretation. Subsequently, the absolute configuration of 1 was determined using advanced Marfey's analysis, modified Mosher's ester derivatization, and chiral-phase HPLC. The structures of kavaratamides B (2) and C (3) are proposed based on a detailed analysis of their MS/MS fragmentations. The biological activity of kavaratamide A was also investigated and found to show moderate cytotoxicity to the D283-medullablastoma cell line.
Subject(s)
Cyanobacteria , Depsipeptides , Cyanobacteria/chemistry , Depsipeptides/chemistry , Depsipeptides/pharmacology , Depsipeptides/isolation & purification , Molecular Structure , India , Nuclear Magnetic Resonance, Biomolecular , Marine Biology , Humans , Drug Screening Assays, Antitumor , Chromatography, High Pressure LiquidABSTRACT
The mass proliferation of cyanobacteria, episodes known as blooms, is a concern worldwide. One of the most critical aspects during these blooms is the production of toxic secondary metabolites that are not limited to the four cyanotoxins recognized by the World Health Organization. These metabolites comprise a wide range of structurally diverse compounds that possess bioactive functions. Potential human and ecosystem health risks posed by these metabolites and co-produced mixtures remain largely unknown. We studied acute lethal and sublethal effects measured as impaired mobility on the freshwater microcrustaceans Thamnocephalus platyurus for metabolite mixtures from two cyanobacterial strains, a microcystin (MC) producer and a non-MC producer. Both cyanobacterial extracts, from the MC-producer and non-MC-producer, caused acute toxicity with LC50 (24 h) values of 0.50 and 2.55 mgdw_biomass/mL, respectively, and decreased locomotor activity. Evaluating the contribution of different cyanopeptides revealed that the Micropeptin-K139-dominated fraction from the MC-producer extract contributed significantly to mortality and locomotor impairment of the microcrustaceans, with potential mixture effect with other cyanopeptolins present in this fraction. In the non-MC-producer extract, compounds present in the apolar fraction contributed mainly to mortality, locomotor impairment, and morphological changes in the antennae of the microcrustacean. No lethal or sublethal effects were observed in the fractions dominated by other cyanopetides (Cyanopeptolin 959, Nostoginin BN741). Our findings contribute to the growing body of research indicating that cyanobacterial metabolites beyond traditional cyanotoxins cause detrimental effects. This underscores the importance of toxicological assessments of such compounds, also at sublethal levels.
Subject(s)
Cyanobacteria , Microcystins , Water Pollutants, Chemical , Microcystins/toxicity , Animals , Cyanobacteria/chemistry , Water Pollutants, Chemical/toxicity , Fresh Water/chemistry , Behavior, Animal/drug effects , Anostraca/drug effects , Lethal Dose 50ABSTRACT
Natural toxins, such as mycotoxins and cyanotoxins, can contaminate food and feed, leading to toxicity in humans and animals. This study focused on using nine magnetic nanostructured agents to remove the main types of toxins. Initially, the efficacy of these materials was evaluated in water solutions, revealing that composites with sizes below 3 mm, containing magnetite, activated carbon, esterified pectin, and sodium alginate, removed up to 90% of mycotoxins and cyanotoxins with an adsorption of 873 ng/g. The application of the nanostructures was then assessed in beer, milk, Distillers Dried Grains with Solubles and water contaminated with cyanobacteria. The presence of matrix slightly decreases the adsorption capacity for some toxins. The maximum toxin removal capacity was calculated with cyanotoxins, composites achieved a removal of up to 0.12 mg/g, while nanocomposites (15 µm) reached 36.6 mg/g. Therefore, these findings point out the potential for using nanotechnology in addressing natural toxins contamination.
Subject(s)
Food Contamination , Mycotoxins , Nanostructures , Food Contamination/analysis , Food Contamination/prevention & control , Mycotoxins/chemistry , Mycotoxins/analysis , Adsorption , Nanostructures/chemistry , Animals , Food Chain , Beer/analysis , Milk/chemistry , Bacterial Toxins/chemistry , Cyanobacteria/chemistry , Microcystins/chemistry , Microcystins/analysisABSTRACT
Ongoing research on cyanotoxins, driven by the socioeconomic impact of harmful algal blooms, emphasizes the critical necessity of elucidating the toxicological profiles of algal cell extracts and pure toxins. This study comprehensively compares Raphidiopsis raciborskii dissolved extract (RDE) and cylindrospermopsin (CYN) based on Daphnia magna assays. Both RDE and CYN target vital organs and disrupt reproduction, development, and digestion, thereby causing acute and chronic toxicity. Disturbances in locomotion, reduced behavioral activity, and weakened swimming capability in D. magna have also been reported for both RDE and CYN, indicating the insufficiency of conventional toxicity evaluation parameters for distinguishing between the toxic effects of algal extracts and pure cyanotoxins. Additionally, chemical profiling revealed the presence of highly active tryptophan-, humic acid-, and fulvic acid-like fluorescence compounds in the RDE, along with the active constituents of CYN, within a 15-day period, demonstrating the chemical complexity and dynamics of the RDE. Transcriptomics was used to further elucidate the distinct molecular mechanisms of RDE and CYN. They act diversely in terms of cytotoxicity, involving oxidative stress and response, protein content, and energy metabolism, and demonstrate distinct modes of action in neurofunctions. In essence, this study underscores the distinct toxicity mechanisms of RDE and CYN and emphasizes the necessity for context- and objective-specific toxicity assessments, advocating nuanced approaches to evaluate the ecological and health implications of cyanotoxins, thereby contributing to the precision of environmental risk assessments.
Subject(s)
Alkaloids , Bacterial Toxins , Cyanobacteria Toxins , Cyanobacteria , Daphnia , Animals , Bacterial Toxins/toxicity , Daphnia/drug effects , Alkaloids/toxicity , Cyanobacteria/chemistry , Uracil/analogs & derivatives , Uracil/toxicity , Cell Extracts/chemistry , Cell Extracts/pharmacology , Harmful Algal BloomABSTRACT
Cyanobacterial phycocyanin pigment is widely utilized for its properties in various industries, including food, cosmetics, and pharmaceuticals. Despite its potential, challenges exist, such as extraction methods impacting yield, stability, and purity. This study investigates the impact of the number of freeze-thaw (FT) cycles on the extraction of phycocyanin from the wet biomass of four cyanobacteria species (Arthrospira platensis, Chlorogloeopsis fritschii, Phormidium sp., and Synechocystis sp.), along with the impact of five extraction solutions (Tris-HCl buffer, phosphate buffer, CaCl2, deionized water, and tap water) at various pH values. Synechocystis sp. exhibited the highest phycocyanin content among the studied species. For A. platensis, Tris-HCl buffer yielded maximum phycocyanin concentration from the first FT cycle, while phosphate buffer provided satisfactory results from the second cycle. Similarly, Tris-HCl buffer showed promising results for C. fritschii (68.5% of the maximum from the first cycle), with the highest concentration (~12% w/w) achieved during the seventh cycle, using phosphate buffer. Phormidium sp. yielded the maximum pigment concentration from the first cycle using tap water. Among species-specific optimal extraction solutions, Tris-HCl buffer demonstrated sufficient extraction efficacy for all species, from the first cycle. This study represents an initial step toward establishing a universal extraction method for phycocyanin from diverse cyanobacteria species.
Subject(s)
Biomass , Cyanobacteria , Phycocyanin , Solvents , Phycocyanin/isolation & purification , Phycocyanin/chemistry , Cyanobacteria/chemistry , Solvents/chemistry , Freezing , Hydrogen-Ion ConcentrationABSTRACT
The rise in cyanobacterial blooms due to eutrophication and climate change has increased cyanotoxin presence in water. Most current water treatment plants do not effectively remove these toxins, posing a potential risk to public health. This study introduces a water treatment approach using nanostructured beads containing magnetic nanoparticles (MNPs) for easy removal from liquid suspension, coated with different adsorbent materials to eliminate cyanotoxins. Thirteen particle types were produced using activated carbon, CMK-3 mesoporous carbon, graphene, chitosan, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidised cellulose nanofibers (TOCNF), esterified pectin, and calcined lignin as an adsorbent component. The particles' effectiveness for detoxification of microcystin-LR (MC-LR), cylindrospermopsin (CYN), and anatoxin-A (ATX-A) was assessed in an aqueous solution. Two particle compositions presented the best adsorption characteristics for the most common cyanotoxins. In the conditions tested, mesoporous carbon nanostructured particles, P1-CMK3, provide good removal of MC-LR and Merck-activated carbon nanostructured particles, P9-MAC, can remove ATX-A and CYN with high and fair efficacy, respectively. Additionally, in vitro toxicity of water treated with each particle type was evaluated in cultured cell lines, revealing no alteration of viability in human renal, neuronal, hepatic, and intestinal cells. Although further research is needed to fully characterise this new water treatment approach, it appears to be a safe, practical, and effective method for eliminating cyanotoxins from water.
Subject(s)
Bacterial Toxins , Cyanobacteria Toxins , Marine Toxins , Microcystins , Water Purification , Cyanobacteria Toxins/chemistry , Humans , Microcystins/toxicity , Microcystins/chemistry , Microcystins/isolation & purification , Marine Toxins/toxicity , Marine Toxins/chemistry , Marine Toxins/isolation & purification , Water Purification/methods , Adsorption , Bacterial Toxins/toxicity , Bacterial Toxins/chemistry , Bacterial Toxins/isolation & purification , Alkaloids/chemistry , Alkaloids/toxicity , Magnetite Nanoparticles/chemistry , Magnetite Nanoparticles/toxicity , Tropanes/chemistry , Tropanes/toxicity , Tropanes/isolation & purification , Nanostructures/chemistry , Nanostructures/toxicity , Uracil/analogs & derivatives , Uracil/chemistry , Uracil/toxicity , Cyanobacteria/chemistry , Cell Survival/drug effects , Water Pollutants, Chemical/toxicity , Water Pollutants, Chemical/chemistryABSTRACT
Current small-molecule-based SARS-CoV-2 treatments have limited global accessibility and pose the risk of inducing viral resistance. Therefore, a marine algae and cyanobacteria extract library was screened for natural products that could inhibit two well-defined and validated COVID-19 drug targets, disruption of the spike protein/ACE-2 interaction and the main protease (Mpro) of SARS-CoV-2. Following initial screening of 86 extracts, we performed an untargeted metabolomic analysis of 16 cyanobacterial extracts. This approach led to the isolation of an unusual saturated fatty acid, jobosic acid (2,5-dimethyltetradecanoic acid, 1). We confirmed that 1 demonstrated selective inhibitory activity toward both viral targets while retaining some activity against the spike-RBD/ACE-2 interaction of the SARS-CoV-2 omicron variant. To initially explore its structure-activity relationship (SAR), the methyl and benzyl ester derivatives of 1 were semisynthetically accessed and demonstrated acute loss of bioactivity in both SARS-CoV-2 biochemical assays. Our efforts have provided copious amounts of a fatty acid natural product that warrants further investigation in terms of SAR, unambiguous determination of its absolute configuration, and understanding of its specific mechanisms of action and binding site toward new therapeutic avenues for SARS-CoV-2 drug development.
Subject(s)
Antiviral Agents , Metabolomics , SARS-CoV-2 , SARS-CoV-2/drug effects , Antiviral Agents/pharmacology , Antiviral Agents/chemistry , Antiviral Agents/isolation & purification , Humans , Cyanobacteria/chemistry , Structure-Activity Relationship , Fatty Acids/chemistry , Fatty Acids/pharmacology , COVID-19 , Molecular Structure , Coronavirus 3C Proteases/antagonists & inhibitors , Coronavirus 3C Proteases/metabolismABSTRACT
Cyanobacteria bloom is the term used to describe an abnormal and rapid growth of cyanobacteria in aquatic ecosystems such as lakes, rivers, and oceans as a consequence of anthropic factors, ecosystem degradation, or climate change. Cyanobacteria belonging to the genera Microcystis, Anabaena, Planktothrix, and Nostoc produce and release toxins called microcystins (MCs) into the water. MCs can have severe effects on human and animal health following their ingestion and inhalation. The MC structure is composed of a constant region (composed of five amino acid residues) and a variable region (composed of two amino acid residues). When the MC variable region is composed of arginine and leucine, it is named MC-LR. The most-common methods used to detect the presence of MC-LR in water are chromatographic-based methods (HPLC, LC/MS, GC/MS) and immunological-based methods (ELISA). In this work, we developed a new competitive Förster resonance energy transfer (FRET) assay to detect the presence of traces of MC-LR in water. Monoclonal antibody anti-MC-LR and MC-LR conjugated with bovine serum albumin (BSA) were labeled with the near-infrared fluorophores CF568 and CF647, respectively. Steady-state fluorescence measurements were performed to investigate the energy transfer process between anti-MC-LR 568 and MC-LR BSA 647 upon their interaction. Since the presence of unlabeled MC-LR competes with the labeled one, a lower efficiency of FRET process can be observed in the presence of an increasing amount of unlabeled MC-LR. The limit of detection (LoD) of the FRET assay is found to be 0.245 nM (0.245 µg/L). This value is lower than the provisional limit established by the World Health Organization (WHO) for quantifying the presence of MC-LR in drinking water.
Subject(s)
Drinking Water , Fluorescence Resonance Energy Transfer , Marine Toxins , Microcystins , Microcystins/analysis , Microcystins/immunology , Fluorescence Resonance Energy Transfer/methods , Drinking Water/analysis , Drinking Water/chemistry , Marine Toxins/analysis , Cyanobacteria/chemistry , Humans , Animals , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/chemistryABSTRACT
Far-red cyanobacteriochromes (CBCRs) are bilin-based photosensory proteins that promise to be novel optical agents in optogenetics and deep tissue imaging. Recent structural studies of a far-red CBCR 2551g3 have revealed a unique all-Z,syn chromophore conformation in the far-red-absorbing Pfr state. Understanding the photoswitching mechanism through bilin photoisomerization is important for developing novel biomedical applications. Here, we employ femtosecond spectroscopy and site-directed mutagenesis to systematically characterize the dynamics of wild-type 2551g3 and four critical mutants in the 15Z Pfr state. We captured local relaxations in several picoseconds and isomerization dynamics in hundreds of picoseconds. Most mutants exhibited faster local relaxation, while their twisting dynamics and photoproducts depend on specific protein-chromophore interactions around the D-ring and C-ring. These results collectively reveal a unique dynamic pattern of excited-state evolution arising from a relatively rigid protein environment, thereby elucidating the molecular mechanism of Pfr-state photoisomerization in far-red CBCRs.
Subject(s)
Bacterial Proteins , Isomerism , Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Cyanobacteria/metabolism , Cyanobacteria/chemistry , Mutagenesis, Site-Directed , Photoreceptors, Microbial/chemistry , Photoreceptors, Microbial/metabolism , Bile Pigments/chemistry , Bile Pigments/metabolismABSTRACT
Exploring the chemical diversity present in cyanobacterial mats increasingly frequent in fresh and marine waters is imperative for both evaluating risks associated with these diverse biofilms and their potential for biodiscovery. During a project aimed at the study of the (eco)toxicity of benthic cyanobacteria blooming in some lakes of the West of Ireland, three previously undescribed ahp-cyclodepsipeptides micropeptin LOF941 (1), micropeptin LOF925 (2) and micropeptin LOF953 (3) were isolated from the Microcoleus autumnalis-dominated benthic cyanobacterial biofilm collected from the shore of Lough O'Flynn, Co. Roscommon, Ireland. Their structures remain consistent in their amino acid sequence with the presence of an unusual methionine, and differ by their exocyclic side chains. The planar structures of the previously undescribed micropeptins were elucidated by 1D and 2D NMR and HRESIMS analyses, and their 3D configurations assessed by ROESY NMR and Marfey's analyses. The three isolated compounds showed no cytotoxic effects and all three compounds were shown to exhibit antioxidant properties, with 1 showing the highest bioactivity. Additionally, several micropeptin analogues are proposed from the methanolic fraction of the biofilm extract by UHPLC-HRESIMS/MS analysis and molecular networking. Notably, the known cyanotoxins anatoxin-a and dihydroanatoxin-a were annotated in the molecular network therefore raising issues about the toxicity of this cyanobacterial mat.
Subject(s)
Antioxidants , Cyanobacteria , Depsipeptides , Cyanobacteria/chemistry , Antioxidants/chemistry , Antioxidants/pharmacology , Antioxidants/isolation & purification , Ireland , Depsipeptides/chemistry , Depsipeptides/isolation & purification , Depsipeptides/pharmacology , Biofilms/drug effects , Molecular Structure , HumansABSTRACT
Biocrust inoculation and microbially induced carbonate precipitation (MICP) are tools used in restoring degraded arid lands. It remains unclear whether the ecological functions of the two tools persist when these methods are combined and subjected to freeze-thaw (FT) cycles. We hypothesized a synergetic interaction between MICP treatment and biocrust under FT cycles, which would allow both components to retain their ecological functions. We grew cyanobacterial (Nostoc commune) biocrusts on bare soil and on MICP (Sporosarcina pasteurii)-treated soil, subjecting them to repeated FT cycles simulating the Mongolian climate. Generalized linear modeling revealed that FT cycling did not affect physical structure or related functions but could increase the productivity and reduce the nutrient condition of the crust. The results confirm the high tolerance of MICP-treated soil and biocrust to FT cycling. MICP treatment + biocrust maintained higher total carbohydrate content under FT stress. Our study indicates that biocrust on biomineralized soil has a robust enough structure to endure FT cycling during spring and autumn and to promote restoration of degraded lands.
Subject(s)
Cyanobacteria , Freezing , Soil Microbiology , Soil , Soil/chemistry , Cyanobacteria/metabolism , Cyanobacteria/chemistry , Carbonates/chemistry , Carbonates/metabolism , Ecosystem , Sporosarcina/metabolism , Sporosarcina/growth & developmentABSTRACT
Jamaicamide B was isolated from the cyanobacterium Moorea producens in Jamaica and shows neurotoxicity. This unique mixed peptide-polyketide structure contains a pyrrolinone ring, a ß-methoxy enone, an (E)-olefin, an undetermined stereocenter at C9, an (E)-chloroolefin, and a terminal alkyne. We report herein the first total synthesis and structural confirmation of the marine natural product (9R)-jamaicamide B.