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- Research Article
- 10.1016/j.ejpb.2025.114906
- Oct 1, 2025
- European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V
- Noelia Perez + 5 more
Mucus-penetrating archaeolipid nanocarriers delivering Thymus vulgaris essential oil and tobramycin: A multifunctional approach against Pseudomonas aeruginosa biofilms and inflammation.
- Research Article
- 10.3390/ijms26178607
- Sep 4, 2025
- International Journal of Molecular Sciences
- Victoria Rebeca Dana González Epelboim + 10 more
The membranes of halophilic archaea are a source of novel biomaterials, mainly of isoprenoid nature, with therapeutic properties practically unraveled. Here, we explored the antitumoral activity of neutral archaeolipids (NAs, such as bacterioruberin, astaxanthin, and dihydrosqualene) present in the total archaeolipids (TAs) (a fraction from the first step of lipid extraction by the modified Blight and Dyer technique) extracted from halophilic archaea Halorubrum tebenquichense, and formulated as TA-nanoarchaeosomes (TA: polar archaeolipids (PAs): Tween 80, 5:5:4 w:w:w, TA-nanoARC). The structure of 300.3 ± 84.2 nm TA-nanoARC of 0.59 ± 0.12 polydispersity index and −20 ± 3.7 mV ζ potential as determined by SAXS modelling, revealed that NA reduced the hydrophobic core and enlarged its hydrophilic section in comparison to TA-lacking bilayers (nanoARC), while preserving the width (~50 Å) and unilamellarity. Stable to storage and nebulization, TA-nanoARC was cytotoxic on A549 cells after 48 h, with an IC50 expressed as [bacterioruberin] of 0.15 μg/mL (~0.20 µM), comparable to or lower than the IC50 of docetaxel or cisplatin. Such cytotoxicity was exerted at a concentration harmless to macrophages (mTHP-1 cells). Besides, the conditioned medium from TA-nanoARC nebulized on A549 cells reduced the expression of the CD204/SRA-1, an M2 phenotype marker, and induced pro-inflammatory activity, comparable to or to a greater extent than that induced by lipopolysaccharide, including IL-6 and TNF-α, in mTHP-1 as a model of tumor-associated macrophages. The endocytosis of TA-nanoARC by A549 cells induced Lysotracker red fluorescence to fade and blur. This suggested the internalization of the highly viscous and ordered TA-nanoARC rich in NAs and subsequent lysosomal dysfunction (and not its antioxidant activity), as responsible for the selective damage on A549 cells. These are the first results showing that nebulized TA-nanoARC, lethal to A549 cells and modulating mTHP-1 cell phenotype, may act as antitumorals in the absence of cytotoxic drugs.
- Research Article
- 10.3390/ijms26010392
- Jan 4, 2025
- International journal of molecular sciences
- Sofia Giuliana Guerin Stabile + 10 more
The properties of two hybrid nanoarchaeosomes (hybrid nanoARCs) made of archaeolipids extracted from the halophilic archaea Halorubrum tebenquichense and combining the properties of archaeolipid bilayers with metallic nanoparticles are explored here. BS-nanoARC, consisting of a nanoARC loaded with yerba mate (Ilex paraguariensis) extract (YME)-biogenic silver nanoparticles (BSs), and [BS + BS-nanoARC], consistent of a BS-nanoARC core covered by an outer shell of BSs, were structurally characterized and their therapeutic activities screened. By employing 109 ± 5 µg gallic acid equivalents (GAEs) and 73.4 µg chlorogenic acid/ YME mg as a silver reductive agent, spherical, heterogeneously sized (~80 nm diameter), -27 mV ζ potential, 90% Ag0 and λmax 420 nm BSs were obtained. We further prepared ~100-200 nm diameter, -57 mV ζ potential BS-nanoARC and ~300 nm diameter, -37 mV ζ potential [BS + BS-nanoARCs]. Freshly prepared and nebulized BS-nanoARCs reduced the release of TNF-α, IL-6 and IL-8 by LPS-irritated THP-1-macrophages and were highly anti-planktonic against S. aureus (MIC90: 13 ± 0.8 µg Ag/mL). While the nanoARCs and BS-nanoARCs were innocuous, freshly prepared [BS + BS-nanoARCs] magnified the cytotoxicity of BSs (IC50 12 µg Ag/mL vs. IC50 ~36 µg Ag/mL) on A549 cells. Such cytotoxicity remained after 30 days in the dark at 4 °C, while that of BSs was lost. Freshly prepared BSs also lost activity upon nebulization, whereas freshly prepared [BS + BS-nanoARCs] did not. However, the cytotoxicity of the [BS + BS-nanoARCs] was also lost when nebulized after 30 days of storage. Despite the harmful effects of storage and mechanical stress on the structure of the more active [BS + BS-nanoARCs], hybrid nanoARCs are promising examples of nanomedicines combining the properties of archaeolipids with antimicrobial silver nanoparticles and anti-inflammatory polyphenols that could complement oncologic therapies, reducing the usage of classical antitumoral agents, corticosteroids, and, importantly, of antibiotics, as well as their waste.
- Research Article
- 10.31857/s0026365624040075
- Dec 5, 2024
- Microbiology
- А S Balkin + 4 more
The complete genome sequence of a new strain of the haloarchaeaon Halorubrum distributum ICIS4 was revealed and analyzed. The strain was isolated from a culture of a carotenogenic microalga Dunaliella salina maintained in laboratory conditions for a long period of time. The genome (3.32 Mb) contained 3236 protein-coding genes. Of the 2817 groups of homologous genes, 11 were unique to this strain. In the genome, the genes were revealed, which were responsible for utilization of glycerol and starch and for synthesis of vitamins, pigments, and siderophores. These genes may be involved in formation and maintenance of the association with microalgae. A region similar to the HRPV9 virus and another circular contig similar to a phage of the haloarchaean Haloquadratum walsbyi were revealed in the genome assembly.
- Research Article
3
- 10.1016/j.syapm.2024.126553
- Sep 17, 2024
- Systematic and Applied Microbiology
- Luciana Albuquerque + 7 more
One hundred and sixty-three extreme halophiles were recovered from a single sample collected from an inland solar saltern in Rio Maior. Based on random amplified polymorphic DNA (RAPD) profiles and partial 16S rRNA gene sequencing 125 isolates were identified as members of the Archaea domain within the genus Halorubrum. Two strains, RMP-11T and RMP-47, showed 99.1 % sequence similarity with the species Halorubrum californiense based on phylogenetic analysis of the 16S rRNA gene sequence. However, phylogenetic analysis based on five housekeeping genes, atpB, EF-2, glnA, ppsA and rpoB’, showed Halorubrum coriense as the closest related species with 96.7 % similarity. The average nucleotide identity (ANI) of strains RMP-11T, RMP-47 and species Hrr. coriense were within the range of 90.0–90.5 %, supporting that strains RMP-11T and RMP-47 represent a novel species of the genus Halorubrum. These strains formed red-pigmented colonies that were able to grow in a temperature range of 25–50 °C. Polyhydroxyalkanoate (PHA) granules were detected in both strains. The polar lipid profile was identical to the neutrophilic species of the genus Halorubrum. The Rio Maior sample from which both strains were isolated was metagenome sequenced. We identified five metagenome-assembled genomes representing novel Halorubrum species but distinct from the species represented by strains RMP-11T and RMP-47. Based on phylogenetic, phylogenomic, comparative genomics, physiological and chemotaxonomic parameters, we describe a new species of the genus Halorubrum represented by strains RMP-11T (=CECT 30760T = DSM 115521T) and RMP-47 (=CECT 30761 = DSM 115541) for which we propose the name Halorubrum miltondacostae sp. nov.
- Research Article
6
- 10.1038/s41467-024-49962-y
- Jul 31, 2024
- Nature Communications
- Joshua N Hamm + 13 more
DPANN archaea are a diverse group of microorganisms characterised by small cells and reduced genomes. To date, all cultivated DPANN archaea are ectosymbionts that require direct cell contact with an archaeal host species for growth and survival. However, these interactions and their impact on the host species are poorly understood. Here, we show that a DPANN archaeon (Candidatus Nanohaloarchaeum antarcticus) engages in parasitic interactions with its host (Halorubrum lacusprofundi) that result in host cell lysis. During these interactions, the nanohaloarchaeon appears to enter, or be engulfed by, the host cell. Our results provide experimental evidence for a predatory-like lifestyle of an archaeon, suggesting that at least some DPANN archaea may have roles in controlling host populations and their ecology.
- Research Article
- 10.1080/01490451.2024.2381008
- Jul 1, 2024
- Geomicrobiology Journal
- Salma Mukhtar + 3 more
Halophilic microorganisms play a crucial role in plant health and growth in salinity affected lands. The objective of this study was to evaluate the haloarchaeal diversity from the rhizosphere of halophytes and plant growth promoting abilities of these strains. The whole genome sequences of two haloarchaeal strains, Halorubrum lacusprofundi HL1RP11 and Halobacterium noricense NRS2HaP9, were analyzed, and genes related to plant growth promoting traits were identified. Phylogenetic analysis showed that archaeal strains of Halococcus, Halorubrum, Halobacterium and Natrinema were dominant in the rhizosphere of halophytes. More than 60% of the strains were positive for phosphate solubilization and IAA production. About 33% were siderophore producers. More than 40% of haloarchaeal strains showed the heavy metal resistance for Nickel, Cadmium, Chromium and Zinc at a concentration of 5 mM. Genes involved in plant growth promotion were identified through annotation. Gene clusters related to secondary metabolites including phenazine, siderophore production and terpene were also identified in this study. Our results suggested that these haloarchaeal strains can be used as an eco-friendly biofertilizer to improve growth and productivity in hypersaline environment.
- Research Article
3
- 10.3762/bjnano.15.46
- May 13, 2024
- Beilstein Journal of Nanotechnology
- Horacio Emanuel Jerez + 4 more
Sodium alendronate (ALN) is a very hydrosoluble and poorly permeable molecule used as an antiresorptive agent and with vascular anticalcifying capacity. Loaded into targeted nanovesicles, its anti-inflammatory activity may be amplified towards extra-osseous and noncalcified target cells, such as severely irritated vascular endothelium. Here cytotoxicity, mitochondrial membrane potential, ATP content, and membrane fluidity of human endothelial venous cells (HUVECs) were determined after endocytosis of ALN-loaded nanoarchaeosomes (nanoARC-Chol(ALN), made of polar lipids from Halorubrum tebenquichense: cholesterol 7:3 w/w, 166 ± 5 nm, 0.16 ± 0.02 PDI, -40.8 ± 5.4 mV potential, 84.7 ± 21 µg/mg ALN/total lipids, TL). The effect of nanoARC-Chol(ALN) was further assessed on severely inflamed HUVECs. To that aim, HUVECs were grown on a porous barrier on top of a basal compartment seeded either with macrophages or human foam cells. One lighter and one more pronounced inflammatory context was modelled by adding lipopolysaccharide (LPS) to the apical or the apical and basal compartments. The endocytosis of nanoARC-Chol(ALN), was observed to partly reduce the endothelial-mesenchymal transition of HUVECs. Besides, while 10 mg/mL dexamethasone, 7.6 mM free ALN and ALN-loaded liposomes failed, 50 μg/mL TL + 2.5 μg/mL ALN (i.e., nanoARC-Chol(ALN)) reduced the IL-6 and IL-8 levels by, respectively, 75% and 65% in the mild and by, respectively, 60% and 40% in the pronounced inflammation model. This is the first report showing that the endocytosis of nanoARC-Chol(ALN) by HUVECs magnifies the anti-inflammatory activity of ALN even under conditions of intense irritation, not only surpassing that of free ALN but also that of dexamethasone.
- Research Article
2
- 10.3390/microorganisms12010005
- Dec 19, 2023
- Microorganisms
- Dominik Lücking + 2 more
Even though viruses and plasmids are both drivers of horizontal gene transfer, they differ fundamentally in their mode of transfer. Virus genomes are enclosed in virus capsids and are not dependent on cell-to-cell contacts for their dissemination. In contrast, the transfer of plasmids most often requires physical contact between cells. However, plasmid pR1SE of Halorubrum lacusprofundi is disseminated between cells, independent of cell-cell contacts, in specialized membrane vesicles that contain plasmid proteins. In this study, we searched for pR1SE-like elements in public databases and a metagenomics dataset from Australian salt lakes and identified 40 additional pR1SE-like elements in hypersaline environments worldwide. Herein, these elements are named apHPVs (archaeal plasmids of haloarchaea potentially transferred in plasmid vesicles). They share two sets of closely related proteins with conserved synteny, strongly indicating an organization into different functional clusters. We find that apHPVs, besides transferring themselves, have the potential to transfer large fragments of DNA between host cells, including virus defense systems. Most interestingly, apHPVs likely play an important role in the evolution of viruses and plasmids in haloarchaea, as they appear to recombine with both of them. This further supports the idea that plasmids and viruses are not distinct but closely related mobile genetic elements.
- Research Article
7
- 10.1002/jobm.202300330
- Oct 17, 2023
- Journal of Basic Microbiology
- Fevziye Işıl Kesbiç + 1 more
Microorganisms that can survive in saline environments, known as halotolerant or halophilic organisms, have a wide range of current and potential uses in biotechnology. In this study, it was aimed to determine the carotenoids of halophilic archaea strains isolated from the brine samples taken from different points of Salt Lake (Turkey) and determine the antioxidant activities of their carotenoids. To identify the halophilic archaea strains, they were cultivated in MAM JCM 168 medium and subjected to antibiotic susceptibility, fatty acid, two-dimensional and three-dimensional imaging by scanning electron microscopy and atomic force microscopy, biochemical and phylogenetic assays. The findings show that five different halophilic archaea strains have been identified as Halorubrum lipolyticum, Halorubrum sodomense, Haloarcula salaria, Halorubrum chaoviator, and Haloarcula japonica with 98% and above similarity ratio. The main fatty acids of all haloarchaeal strains were octadecanoic acid (C18:0) and palmitic acid (C16:0). The major carotenoid of the species was determined as all-trans bacterioruberin, and different carotenoid types such as lycopene, β-carotene, and 2-isopentenyl-3,4-dehydrorodopin were found as well as bacterioruberin isomers. The antioxidant activities of carotenoids extracted from the species were analyzed by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging method and the extracts showed antioxidant activity statistically significantly higher than ascorbic acid and butylated hydroxytoluene as reference products (p < 0.05).
- Research Article
8
- 10.3390/microorganisms11092344
- Sep 19, 2023
- Microorganisms
- Mariana Delgado-Garcia + 6 more
Natural pigments from haloarchaea are of great interest; bacterioruberin is the major pigment, it shows higher antioxidant power when compared with β-carotene. However, characterization of bacterioruberin and its isomers along with its antioxidant and the matrix metallopeptidase 9 (MMP-9) inhibition activities in extracts from Natronoccoccus sp. TC6 and Halorubrum tebenquichense SU10 was not previously described, being the aim of this work. The carotenoids profile was performed by UV-Vis spectrophotometry, thin-layer chromatography, nuclear magnetic resonance spectroscopy, and high-resolution mass spectrometry (UPLC-ESI-MS/MS). Antioxidant capacity was determined for DPPH, ABTS, and FRAP. In addition, MMP-9 inhibition was studied using docking simulations. The carotenoid profile of studied strains was composed of bacterioruberin, some derivatives like mono, bis, and tris anhydrobacterioruberin, and also some bacterioruberin cis isomers. The carotenoid pools showed antioxidant capacity for DPPH > ABTS > FRAP; Natronococcus sp. TC6 carotenoid pool was better for ABTS and DPPH, while Halorubrum tebenquichense SU10 carotenoid pool was better for FRAP. Additionally, docking and molecular dynamics suggest that bacterioruberin inhibits MMP-9 through hydrophobic interactions near the catalytic site. Bacterioruberin shows the higher binding energy of −8.3 (kcal/mol). The carotenoids profile of both strains was elucidated, their antioxidant activity and singular participation of each carotenoid on MMP-9 in silico inhibition were evaluated.
- Research Article
6
- 10.3389/fmicb.2023.1274068
- Sep 18, 2023
- Frontiers in Microbiology
- Coraline Mercier + 4 more
Halophilic archaea (haloarchaea) are known to exhibit multiple chromosomes, with one main chromosome and one or several smaller secondary chromosomes or megaplasmids. Halorubrum lacusprofundi, a model organism for studying cold adaptation, exhibits one secondary chromosome and one megaplasmid that include a large arsenal of virus defense mechanisms. We isolated a virus (Halorubrum tailed virus DL1, HRTV-DL1) infecting Hrr. lacusprofundi, and present an in-depth characterization of the virus and its interactions with Hrr. lacusprofundi. While studying virus-host interactions between Hrr. lacusprofundi and HRTV-DL1, we uncover that the strain in use (ACAM34_UNSW) lost the entire megaplasmid and about 38% of the secondary chromosome. The loss included the majority of virus defense mechanisms, making the strain sensitive to HRTV-DL1 infection, while the type strain (ACAM34_DSMZ) appears to prevent virus replication. Comparing infection of the type strain ACAM34_DSMZ with infection of the laboratory derived strain ACAM34_UNSW allowed us to identify host responses to virus infection that were only activated in ACAM34_UNSW upon the loss of virus defense mechanisms. We identify one of two S-layer proteins as primary receptor for HRTV-DL1 and conclude that the presence of two different S-layer proteins in one strain provides a strong advantage in the arms race with viruses. Additionally, we identify archaeal homologs to eukaryotic proteins potentially being involved in the defense against virus infection.
- Research Article
- 10.51753/flsrt.1299840
- Aug 30, 2023
- Frontiers in Life Sciences and Related Technologies
- Simge Emli̇k + 1 more
Humankind has been curious about the sky and beyond since its existence. Since the most primitive times, researchers have been trying to find answers to this curiosity. In recent years, a relatively new discipline, astrobiology, has emerged to answers to frequently asked questions. Astrobiology is an interdisciplinary field that tries to explain beyond the sky, and extraterrestrial life, where life origin came from, evolution, and the big bang. Extremophiles draw attention as the only creatures that will enlighten us in understanding extraterrestrial conditions and the mechanisms of creatures living in these conditions. This review examines the recent discoveries and the principal advances concerning both bacteria (Chroococcidiopsis sp., Colwellia psychrerythraea, Planococcus halocryophilus) and archaea (Halorubrum lacusprofundi and Halobacterium salinarum NRC-1) species which have potentials to examine in astrobiology as model organisms. Obtaining findings from different studies open new perspectives and strategies for several unresolved questions in astrobiology.
- Research Article
11
- 10.3390/v15071469
- Jun 28, 2023
- Viruses
- L Johanna Gebhard + 4 more
N-glycosylation is a post-translational modification of proteins that occurs across all three domains of life. In Archaea, N-glycosylation is crucial for cell stability and motility, but importantly also has significant implications for virus–host interactions. While some archaeal viruses present glycosylated proteins or interact with glycosylated host proteins, the direct influence of N-glycosylation on archaeal virus–host interactions remains to be elucidated. In this study, we generated an N-glycosylation-deficient mutant of Halorubrum lacusprofundi, a halophilic archaeon commonly used to study cold adaptation, and examined the impact of compromised N-glycosylation on the infection dynamics of two very diverse viruses. While compromised N-glycosylation had no influence on the life cycle of the head-tailed virus HRTV-DL1, we observed a significant effect on membrane-containing virus HFPV-1. Both intracellular genome numbers and extracellular virus particle numbers of HFPV-1 were increased in the mutant strain, which we attribute to instability of the surface-layer which builds the protein envelope of the cell. When testing the impact of compromised N-glycosylation on the life cycle of plasmid vesicles, specialized membrane vesicles that transfer a plasmid between host cells, we determined that plasmid vesicle stability is strongly dependent on the host glycosylation machinery. Our study thus provides important insight into the role of N-glycosylation in virus–host interactions in Archaea, while pointing to how this influence strongly differs amongst various viruses and virus-like elements.
- Research Article
7
- 10.1111/1462-2920.16451
- Jun 22, 2023
- Environmental Microbiology
- Lorenzo Carré + 3 more
Halophilic archaea thriving in hypersaline environments, such as salt lakes, offer models for putative life in extraterrestrial brines such as those found on Mars. However, little is known about the effect of the chaotropic salts that could be found in such brines, such as MgCl2 , CaCl2 and (per)chlorate salts, on complex biological samples like cell lysates which could be expected to be more representative of biomarkers left behind putative extraterrestrial life forms. We used intrinsic fluorescence to study the salt dependence of proteomes extracted from five halophilic strains: Haloarcula marismortui, Halobacterium salinarum, Haloferax mediterranei, Halorubrum sodomense and Haloferax volcanii. These strains were isolated from Earth environments with different salt compositions. Among the five strains that were analysed, H. mediterranei stood out as a results of its high dependency on NaCl for its proteome stabilization. Interestingly, the results showed contrasting denaturation responses of the proteomes to chaotropic salts. In particular, the proteomes of strains that are most dependent or tolerant on MgCl2 for growth exhibited higher tolerance towards chaotropic salts that are abundant in terrestrial and Martian brines. These experiments bridge together global protein properties and environmental adaptation and help guide the search for protein-like biomarkers in extraterrestrial briny environments.
- Research Article
6
- 10.3390/microorganisms11051271
- May 12, 2023
- Microorganisms
- Thomas P Thompson + 2 more
Quorum Sensing (QS) is a well-studied intercellular communication mechanism in bacteria, regulating collective behaviors such as biofilm formation, virulence, and antibiotic resistance. However, cell-cell signaling in haloarchaea remains largely unexplored. The coexistence of bacteria and archaea in various environments, coupled with the known cell-cell signaling mechanisms in both prokaryotic and eukaryotic microorganisms and the presence of cell-cell signaling mechanisms in both prokaryotic and eukaryotic microorganisms, suggests a possibility for haloarchaea to possess analogous cell-cell signaling or QS systems. Recently, N-acylhomoserine lactone (AHL)-like compounds were identified in haloarchaea; yet, their precise role-for example, persister cell formation-remains ambiguous. This study investigated the capacity of crude supernatant extract from the haloarchaeon Halorubrum saccharovorum CSM52 to stimulate bacterial AHL-dependent QS phenotypes using bioreporter strains. Our findings reveal that these crude extracts induced several AHL-dependent bioreporters and modulated pyocyanin and pyoverdine production in Pseudomonas aeruginosa. Importantly, our study suggests cross-domain communication between archaea and bacterial pathogens, providing evidence for archaea potentially influencing bacterial virulence. Using Thin Layer Chromatography overlay assays, lactonolysis, and colorimetric quantification, the bioactive compound was inferred to be a chemically modified AHL-like compound or a diketopiperazine-like molecule, potentially involved in biofilm formation in H. saccharovorum CSM52. This study offers new insights into putative QS mechanisms in haloarchaea and their potential role in interspecies communication and coordination, thereby enriching our understanding of microbial interactions in diverse environments.
- Research Article
7
- 10.3389/fmicb.2023.1095621
- Mar 31, 2023
- Frontiers in microbiology
- L Johanna Gebhard + 2 more
Halorubrum lacusprofundi is a cold-adapted halophilic archaeon isolated from Deep Lake, Antarctica. Hrr. lacusprofundi is commonly used to study adaptation to cold environments and thereby a potential source for biotechnological products. Additionally, in contrast to other haloarchaeal model organisms, Hrr. lacusprofundi is also susceptible to a range of different viruses and virus-like elements, making it a great model to study virus-host interactions in a cold-adapted organism. A genetic system has previously been reported for Hrr. lacusprofundi; however, it does not allow in-frame deletions and multiple gene knockouts. Here, we report the successful generation of uracil auxotrophic (pyrE2) mutants of two strains of Hrr. lacusprofundi. Subsequently, we attempted to generate knockout mutants using the auxotrophic marker for selection. However, surprisingly, only the combination of the auxotrophic marker and antibiotic selection allowed the timely and clean in-frame deletion of a target gene. Finally, we show that vectors established for the model organism Haloferax volcanii are deployable for genetic manipulation of Hrr. lacusprofundi, allowing the use of the portfolio of genetic tools available for H. volcanii in Hrr. lacusprofundi.
- Research Article
3
- 10.3390/microorganisms11030607
- Feb 28, 2023
- Microorganisms
- Sagorika Nag + 7 more
Ultraviolet (UV) radiation responses of extremophilic and archaeal microorganisms are of interest from evolutionary, physiological, and astrobiological perspectives. Previous studies determined that the halophilic archaeon, Halobacterium sp. NRC-1, which survives in multiple extremes, is highly tolerant of UV radiation. Here, Halobacterium sp. NRC-1 UV tolerance was compared to taxonomically diverse Haloarchaea isolated from high-elevation salt flats, surface warm and cold hypersaline lakes, and subsurface Permian halite deposits. Haloterrigena/Natrinema spp. from subsurface halite deposits were the least tolerant after exposure to photoreactivating light. This finding was attributed to deviation of amino acid residues in key positions in the DNA photolyase enzyme or to the complete absence of the photolyase gene. Several Halobacterium, Halorubrum and Salarchaeum species from surface environments exposed to high solar irradiance were found to be the most UV tolerant, and Halorubrum lacusprofundi from lake sediment was of intermediate character. These results indicate that high UV tolerance is not a uniform character trait of Haloarchaea and is likely reflective of UV exposure experienced in their environment. This is the first report correlating natural UV tolerance to photolyase gene functionality among Haloarchaea and provides insights into their survival in ancient halite deposits and potentially on the surface of Mars.
- Research Article
6
- 10.3390/ijms232415620
- Dec 9, 2022
- International Journal of Molecular Sciences
- Victoria J Laye + 3 more
The polyextremophilic β-galactosidase enzyme of the haloarchaeon Halorubrum lacusprofundi functions in extremely cold and hypersaline conditions. To better understand the basis of polyextremophilic activity, the enzyme was studied using steady-state kinetics and molecular dynamics at temperatures ranging from 10 °C to 50 °C and salt concentrations from 1 M to 4 M KCl. Kinetic analysis showed that while catalytic efficiency (kcat/Km) improves with increasing temperature and salinity, Km is reduced with decreasing temperatures and increasing salinity, consistent with improved substrate binding at low temperatures. In contrast, kcat was similar from 2–4 M KCl across the temperature range, with the calculated enthalpic and entropic components indicating a threshold of 2 M KCl to lower the activation barrier for catalysis. With molecular dynamics simulations, the increase in per-residue root-mean-square fluctuation (RMSF) was observed with higher temperature and salinity, with trends like those seen with the catalytic efficiency, consistent with the enzyme’s function being related to its flexibility. Domain A had the smallest change in flexibility across the conditions tested, suggesting the adaptation to extreme conditions occurs via regions distant to the active site and surface accessible residues. Increased flexibility was most apparent in the distal active sites, indicating their importance in conferring salinity and temperature-dependent effects.
- Research Article
5
- 10.3390/pharmaceutics14122637
- Nov 29, 2022
- Pharmaceutics
- María Julia Altube + 4 more
This study aimed to determine the damage mechanisms caused by naturally targeted nanoarchaeosomes made of diether lipids from Halorubrum tebenquichense loaded with curcumin (CUR, nATC), which mediated photodynamic therapy (PDT) on A549 cells and on THP-1-macrophages, two cell types found in airway cancers. The effect of nATC- PDT on vessels modeled with a chicken embryo chorioallantoic membrane (CAM), after dropping the formulations on its surface covered with mucins, was also determined. nATCs are known to efficiently trap CUR for at least six months, constituting easy-to-prepare, stable formulations suitable for nebulization. CUR instead, is easily released from carriers such as liposomes made of ordinary phospholipids and cholesterol after a few weeks. Irradiated at 9 J/cm2, nATC (made of archaeolipids: Tween 80: CUR at 1:0.4:0.04 w:w, size 180 ± 40 nm, ζ potential −24 mV, 150 μg CUR/15 mg lipids/mL) was phototoxic (3.7 ± 0.5 μM IC50), on A549 cells after 24 h. The irradiation reduced mitochondrial membrane potential (ΔΨm), ATP levels and lysosomal functionalism, and caused early apoptotic death and late necrosis of A549 cells upon 24 h. nATC induced higher extra and intracellular reactive oxygen species (ROS) than free CUR. nATC-PDT impaired the migration of A549 cells in a wound healing assay, reduced the expression of CD204 in THP-1 macrophages, and induced the highest levels of IL-6 and IL-8, suggesting a switch of macrophage phenotype from pro-tumoral M2 to antitumoral M1. Moreover, nATC reduced the matrix metalloproteinases (MMP), −2 and −9 secretion, by A549 cells with independence of irradiation. Finally, remarkably, upon irradiation at 9 J/cm2 on the superficial vasculature of a CAM covered with mucins, nATC caused the vessels to collapse after 8 h, with no harm on non-irradiated zones. Overall, these results suggest that nebulized nATC blue light-mediated PDT may be selectively deleterious on superficial tumors submerged under a thick mucin layer.