Carbonic Anhydrase Activity Research Articles

Silicon dioxide nanoparticles suppress copper toxicity in Mentha arvensis L. by adjusting ROS homeostasis and antioxidant defense system and improving essential oil production

Copper (Cu) is an essential micronutrient for plants; however, the excessive accumulation of Cu due to various anthropogenic activities generates progressive pollution of agricultural land and that causes a major constraint for crop production. Excess Cu (80 mg kg−1) in the soil diminished growth and biomass, photosynthetic efficiency and essential oil (EO) content in Mentha arvensis L., while amplifying the antioxidant enzyme's function and reactive oxygen species (ROS) production. Therefore, there is a pressing need to explore effective approaches to overcome Cu toxicity in M. arvensis plants. Thus, the present study unveils the potential of foliar supplementation of two distinct forms of silicon dioxide nanoparticles (SiO2 NPs) i.e., Aerosil 200F and Aerosil 300 to confer Cu stress tolerance attributes to M. arvensis. The experiment demonstrated that applied forms of SiO2 NPs (120 mg L−1), enhanced plants' growth and augmented the photosynthetic efficiency along with the activities of CA (carbonic anhydrase) and NR (nitrate reductase), however, the effects were more accentuated by Aerosil 200F application. Supplementation of SiO2 NPs also exhibited a beneficial effect on the antioxidant machinery of Cu-disturbed plants by raising the level of proline and total phenol as well as the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX) and glutathione reductase (GR), thereby lowering ROS and electrolytic leakage (EL). Interestingly, SiO2 NPs supplementation upscaled EO production in Cu-stressed plants with more pronounced effects received in the case of Aerosil 200F over Aerosil 300. We concluded that the nano form (Aerosil 200F) of SiO2 proved to be the best in improving the Cu-stress tolerance in plants.

1,5-Diaryl-1,2,4-triazole Ureas as New SLC-0111 Analogues Endowed with Dual Carbonic Anhydrase and VEGFR-2 Inhibitory Activities.

Presently, dual targeting by a single small molecule stands out as an effective cancer-fighting weapon. Carbonic anhydrase (CA) and vascular-endothelial growth factor (VEGF) are hypoxia-activatable genes that are implicated in tumorigenesis and progression of hypoxic tumors at different levels. Herein, we designed and synthesized 30 1,5-diaryl-1,2,4-triazole-tethered sulfonamides (11a-f, 12a-l, 13a-f, 15a-f) as novel SLC-0111 analogues with dual CA IX/XII and VEGFR-2 inhibitory activities. The 4-fluorophenyl SLC-0111 tail was replaced by substituted 1,5-diaryl-1,2,4-triazoles. Changing the sulfamoyl motif position provided regioisomers 11a-f and 12a-l. Elongation of the ureido linker yielded derivatives 15a-f. Inhibitory evaluations included a panel of hCAs (hCA I, II, IX, and XII) and screening against 60 cancer cell lines. Promising candidates were assessed for VEGFR-2 inhibition and selectivity and further evaluated on breast cancer cell lines (MCF-7 and T-47D) and the non-tumorigenic (MCF-10A) cells. Molecular docking studies explored the binding modes of the sulfonamides against hCA IX/XII and VEGFR-2 kinase.

Zinc is incorporated into the exoskeleton during post-ecdysial mineralization and inhibits exoskeletal calcification in the blue crab, Callinectes sapidus

Zinc is an essential but toxic metal with both natural and anthropogenic sources. Zinc has been reported to be present in crustacean exoskeleton, but it has remained unknown as to when zinc is incorporated into the shell during the molting cycle and the effects zinc has on exoskeleton properties. This study was conducted to identify a period during the molting cycle, in which zinc is incorporated into the exoskeleton of the blue crab, Callinectes sapidus, and to identify deleterious effects of zinc incorporation on the exoskeleton. It was hypothesized that zinc would be incorporated into the shell during the mineralization phase using calcium transporters, which would inhibit exoskeletal calcification. Post-ecdysial blue crabs were given two injections of zinc in the form of zinc chloride dissolved in Pantin's crustacean saline at the arthrodial membrane at three treatment levels: 0.0, 1.0 and 5.0 µg Zn/g wet weight. Exoskeletal and hemolymph samples were then analyzed for zinc, calcium, and magnesium content. Gill, muscle, and hepatopancreas samples were analyzed for zinc only. Epidermis samples were analyzed for carbonic anhydrase activity. The results showed that the injection dose of 1.0 µg Zn/g wet weight resulted in significant accumulation of zinc in the exoskeleton. There was no significant accumulation of exoskeletal zinc following 5.0 µg Zn/g wet weight injections. A significant reduction in exoskeletal calcium content in crabs treated with 1.0 or 5.0 µg Zn/g wet weight was also observed. The hypothetical model explaining zinc's incorporation into the exoskeleton and inhibition of exoskeletal calcification is proposed. Additionally, for the soft tissues examined, significant zinc accumulation was only observed in the hepatopancreas following zinc treatment. Our data points to the existence of crustacean zinc transporter. This study is the first to present evidence that zinc is deposited to the exoskeleton during post-ecdysial mineralization and inhibits exoskeletal calcification in a crustacean.

Piperazin incorporated Schiff Base derivatives: Assessment of in vitro biological activities, metabolic enzyme inhibition properties, and molecular docking calculations.

The cytotoxic activities of the compounds were determined by the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) method in human breast cancer (MCF-7), human cervical cancer (HeLa), and mouse fibroblast (L929) cell lines. The compounds MAAS-5 and four modified the supercoiled tertiary structure of pBR322 plasmid DNA. MAAS-5 showed the highest cytotoxic activity in HeLa, MCF-7, and L929 cells with IC50 values of 16.76 ± 3.22, 28.83 ± 5.61, and 2.18 ± 1.22 µM, respectively. MAAS-3 was found to have almost the lowest cytotoxic activities with the IC50 values of 93.17 ± 9.28, 181.07 ± 11.54, and 16.86 ± 6.42 µM in HeLa, MCF-7, and L929 cells respectively at 24 h. Moreover, the antiepileptic potentials of these compounds were investigated in this study. To this end, the effect of newly synthesized Schiff base derivatives on the enzyme activities of carbonic anhydrase I and II isozymes (human carbonic anhydrase [hCA] I and hCA II) was evaluated spectrophotometrically. The target compounds demonstrated high inhibitory activities compared with standard inhibitors with Ki values in the range of 4.54 ± 0.86-15.46 ± 8.65 nM for hCA I (Ki value for standard inhibitor = 12.08 ± 2.00 nM), 1.09 ± 0.32-29.94 ± 0.82 nM for hCA II (Ki value for standard inhibitor = 18.22 ± 4.90 nM). Finally, the activities of the compounds were compared with the Gaussian programme in the B3lyp, HF, M062X base sets with 6-31++G (d,p) levels. In addition, the activities of five compounds against various breast cancer proteins and hCA I and II were compared with molecular docking calculations. Also, absorption, distribution, metabolism, excretion, and toxicity analysis was performed to investigate the possibility of using five compounds as drug candidates.

Synthesis, Single Crystal XRD, In-Silico and In-Vitro Studies of Alkyl Substituted Acyl Thiourea as Carbonic Anhydrase Inhibitor

Carbonic anhydrases (CAs) representing the class of metalloenzymes are expressed widely and play a crucial role in various physiological and pathological processes. The Alkyl substituted Acyl Thiourea was synthesized and characterized by NMR spectroscopic technique. Single crystal X-ray diffraction was applied to determine the molecular and crystal structures. Synthesized compound crystallized in monoclinic system P 21/c space group. Intermolecular N–H···S hydrogen bonds and Intramolecular N–H···O hydrogen bond were found in crystal structure. H … H interactions have major contributions in crystal packing as depicted by Hirshfeld surface analysis. No large cavity was observed during void volume analysis in the crystal packing. Stabilization was dominated via the dispersion energy contributions in the synthesized compound. In Vitro analysis showed that synthesized compound inhibited the carbonic anhydrase activity to an appreciable extent. Quantum mechanical descriptors were calculated using DFT studies. In molecular docking, reactive parts of the synthesized molecule contributed in forming the hydrogen bond with receptor protein target. Finally, ADMET Analysis were performed to assess the drug-like behavior of synthesized compound. Carbonic Anhydrase enzyme inhibitor of pharmaceutical significance can be developed using the synthesized molecule ES-2 as a lead molecule.

The diuretic effect of ethyl acetate fractions of Artocarpus altilis, Artocarpus champeden, and Artocarpus heterophyllus leaves in normotensive Wistar rats

BackgroundArtocarpus altilis, A. Champeden, and Artocarpus heterophylus are popular species in Indonesia, and are commonly used as traditional medicine. ObjectiveThis study aims to evaluate the diuretic effects of the ethyl acetate fraction of these three species on normotensive Wistar rats. MethodsThe ethyl acetate fraction was prepared by a liquid–liquid extraction method. To evaluate diuretic effects, the sixty rats were divided into normal (distilled water), negative (4.5% NaCl), positive control (furosemide 5 mg/kg), and the testing groups. The testing groups were orally given the ethyl acetate fraction of A. altilis, Artocarpus champeden, and A. heterophylus at three dose levels of 25, 50, and 100 mg/kg. All animals were orally given 4.5% NaCl at a dose of 2 mL/200 g except the normal group; then the animals were given drugs according to group doses. Urine volume and electrolyte levels produced by the testing groups were compared to those of the control group. The concentration and ratio of ions were calculated to determine the natriuretic and carbonic anhydrase activities. Results: The ethyl acetate fractions of the three Artocarpus species at 100 mg/kg dose were more active than the standard furosemide (p < 0.05) to increase urinary excretion. Furthermore, at doses of 50 and 100 mg/kg, the fraction significantly increased the excretion of Na+, K+, and Cl- ions more than the standard (p < 0.05). The testing groups showed good natriuretic and carbonic anhydrase activities. ConclusionsThe ethyl acetate fraction of A. altilis, A. champeden, and A. heterophylus leaves performed good diuretic and natriuretic activities. Therefore, the fractions can be considered as potential natural diuretic medicines.

Transport-related enzymes and osmo-ionic regulation in a euryhaline freshwater shrimp after transfer to saline media

To understand the response of freshwater organisms to rising environmental salinity, it is essential to investigate their osmo-ionic regulatory physiology. Our laboratory experiment investigated the transfer of Palaemon argentinus (Nobili, 1901) from 2‰ (control condition) to concentrated salinity (15 and 25‰) for short- (6 h), medium- (48 h), and long-term (&gt;504 h) acclimation periods. We measured relevant parameters in the shrimp’s haemolymph, the time course of the response of branchial V–H+–ATPase (VHA), Na+, K+–ATPase (NKA), carbonic anhydrase (CA) activity, and muscle water content. Upon prolonged acclimation to 15‰ (hyper-regulating condition), shrimp reached a new steady state of haemolymph osmolality by tightly adjusting ion concentrations to levels higher than the external medium. While NKA and CA activities recovered their pre-transfer levels, the downregulation of VHA suggests other functions rather than ion uptake after prolonged acclimation to 15‰. The activity of the three transport-related enzymes remained almost unchanged at the highest salinity (isosmotic condition), leading to increasing osmotic pressure and ion concentration after prolonged acclimation to 25‰. Although the freshwater shrimp studied here retains a certain degree of tolerance to high salinity, a common trait in palaemonid shrimps, our results highlight that 25‰ represents a significant hypertonic challenge for this species.

The vital effects of Bacillus subtilis during carbon isotope fractionation in the process of carbonate precipitation

The carbon isotope composition (δ13C) of biogenic carbonates has been a valuable tool for reconstructing paleoenvironments worldwide. However, the vital effects of microbes during carbon isotope fractionation (CIF) in the process of microbial induced carbonate precipitation (MICP) have not been fully revealed. In this study, calcium carbonate (CaCO3) biomineralization experiments have been performed using the Bacillus subtilis strain 168 under the standing condition. In addition, corresponding shaking experiments and inorganic experiments were also carried out, respectively. We have quantified the temporal change of δ13C values of the carbonate minerals and dissolved inorganic carbon (DIC) as well as the cellular density, Ca2+ and HCO3− concentrations, and the carbonic anhydrase (CA) activity. X-ray diffraction analysis has shown that the precipitates produced by strain 168 were calcite, while no mineral has been formed in abiotic experiments. The values of δ13CCaCO3 fluctuated around −5.2‰ in Bio-standing experiments, whereas δ13CCaCO3 in Ino-standing experiments ranged from −14.1‰ to −13.1‰. The carbon isotope offset (Δ13CCaCO3–DIC) values increased from +0.8‰ to +7.6‰ with incubation and these in Ino-standing experiments increased from −2.3‰ to −0.2‰. These results indicate that bacteria participated in CIF and atmospheric CO2 is the dominant source of carbon in the carbonate minerals. An increase in pH and hydration of CO2 catalyzed by CA played synergetic roles in increasing the saturation index (SI) and accelerating the precipitation rate (R). The values of Δ13CCaCO3-DIC were found to be closely negatively correlated with SI (r = −0.86, P < 0.0001, n = 21), while no clear relationship in inorganic experiments. Moreover, the Δ13CCaCO3-DIC values increased synchronously with the LogR (r = 0.97, P < 0.0001, n = 21), while a negative correlation emerged in inorganic experiments (r = −0.93, P = 0.02, n = 5). Thus, a large CIF could be attributed to the vital effects of bacteria. The shaking condition can affect the CIF during MICP by increasing bacterial activity. These findings emphasize the importance of evaluating vital effects by bacteria during CIF to accurately reconstruct paleoenvironments and highlight the potential of biogenic carbonate minerals for CO2 sequestration.

Mechanistic and structural insights into the bifunctional enzyme PaaY from Acinetobacter baumannii

PaaY is a thioesterase that enables toxic metabolites to be degraded through the bacterial phenylacetic acid (PA) pathway. The Acinetobacter baumannii gene FQU82_01591 encodes PaaY, which we demonstrate to possess γ-carbonic anhydrase activity in addition to thioesterase activity. The crystal structure of AbPaaY in complex with bicarbonate reveals a homotrimer with a canonical γ-carbonic anhydrase active site. Thioesterase activity assays demonstrate a preference for lauroyl-CoA as a substrate. The AbPaaY trimer structure shows a unique domain-swapped C-termini, which increases the stability of the enzyme invitro and decreases its susceptibility to proteolysis invivo. The domain-swapped C-termini impact thioesterase substrate specificity and enzyme efficacy without affecting carbonic anhydrase activity. AbPaaY knockout reduced the growth of Acinetobacter in media containing PA, decreased biofilm formation, and impaired hydrogen peroxide resistance. Collectively, AbPaaY is a bifunctional enzyme that plays a key role in the metabolism,growth, and stress response mechanisms of A.baumannii.

PLBD: protein-ligand binding database ofthermodynamic andkinetic intrinsic parameters.

We introduce a protein-ligand binding database (PLBD) that presents thermodynamic and kinetic data of reversible protein interactions with small molecule compounds. The manually curated binding data are linked to protein-ligand crystal structures, enabling structure-thermodynamics correlations to be determined. The database contains over 5500 binding datasets of 556 sulfonamide compound interactions with the 12 catalytically active human carbonic anhydrase isozymes defined by fluorescent thermal shift assay, isothermal titration calorimetry, inhibition of enzymatic activity and surface plasmon resonance. In the PLBD, the intrinsic thermodynamic parameters of interactions are provided, which account for the binding-linked protonation reactions. In addition to the protein-ligand binding affinities, the database provides calorimetrically measured binding enthalpies, providing additional mechanistic understanding. The PLBD can be applied to investigations of protein-ligand recognition and could be integrated into small molecule drug design. Database URL https://plbd.org/.

Effects of Phosphorylation on the Activity, Inhibition and Stability of Carbonic Anhydrases.

Carbonic anhydrases (CAs) are a metalloenzyme family that have important roles in cellular processes including pH homeostasis and have been implicated in multiple pathological conditions. Small molecule inhibitors have been developed to target carbonic anhydrases, but the effects of post-translational modifications (PTMs) on the activity and inhibition profiles of these enzymes remain unclear. Here, we investigate the effects of phosphorylation, the most prevalent carbonic anhydrase PTM, on the activities and drug-binding affinities of human CAI and CAII, two heavily modified active isozymes. Using serine to glutamic acid (S > E) mutations to mimic the effect of phosphorylation, we demonstrate that phosphomimics at a single site can significantly increase or decrease the catalytic efficiencies of CAs, depending on both the position of the modification and the CA isoform. We also show that the S > E mutation at Ser50 of hCAII decreases the binding affinities of hCAII with well-characterized sulphonamide inhibitors including by over 800-fold for acetazolamide. Our findings suggest that CA phosphorylation may serve as a regulatory mechanism for enzymatic activity, and affect the binding affinity and specificity of small, drug and drug-like molecules. This work should motivate future studies examining the PTM-modification forms of CAs and their distributions, which should provide insights into CA physiopathological functions and facilitate the development of 'modform-specific' carbonic anhydrase inhibitors.

Changes in Java grass (Cymbopogon winterianus) physiology, essential oil production, and active constituents as influenced by catechol and some plant growth regulators applied through steaming technique.

A study was done to find out how steam-applied chemical and plant growth regulators affected plant growth and determine the most effective PGRs and chemical for maximizing java grass oil yield and quality attributes. A chemical viz. catechol and PGRs, viz. indole acetic acid (IAA), kinetin (Kn), 6-benzyl amino purine (BAP), salicylic acid (SA), and triacontanol (TRIA), ethrel, were applied to the plants at a concentration of 5 × 10−6 M at 90 days after transplantation (DAT) through an innovative technique of steaming using an electric steamer five times after a week interval. To prevent the plants from being harmed, we operated the steam jet at a certain distance from them. All the parameters were evaluated at 150 DAT. The results showed that among all these PGRs, IAA proved the best for growth, yield, and other parameters. In comparison to the control, the EO production more than doubled. Our study indicated that IAA enhanced the fresh and dry weight by 30.7% and 42.9%, total chlorophyll and carotenoids contents by 44.1% and 47.1%, nitrate reductase and carbonic anhydrase activity by 18.0% and 28.1%, respectively, over the control. Compared with control, IAA treatment increased the content and yield of essential oil by 96.8% and 155.7%, and the active constituents of EO, i.e., citronellol, citronellal, and geranial content, by 47.4%, 90.9%, and 43.9%, respectively. As a result, IAA used in this technique was very effective in increasing EO production while causing no harm to the plant.

Phenylboronic acid‐functionalized glycogens as dynamic nano‐frameworks for conjugation and activation of carbonic anhydrase

AbstractBiocatalysis is playing an increasingly important role for chemical, pharmaceutical, and food industries, owing to its high efficiency, selectivity and environment‐friendliness. However, it remains challenging to improve the catalytic activity of enzymes since the most frequently used strategies are costly and time‐consuming. In the current study, a new type of glycogen‐based dynamic nano‐frameworks is prepared as additives for the direct activation of carbonic anhydrase (bovine erythrocytes [bCA]). The boronic acid functionalization of the branched glycogen structures can provide NB coordination with bCA, leading to the conjugation and stabilization of the target enzyme. As a result, the glycogen with a 10% substitution degree (Gly‐PBA10) showed a higher activation effect for bCA than that of glycogen with a 20% substitution degree (Gly‐PBA20). Furthermore, the mechanism for interactions between the dynamic frameworks and bCA has been studied through combined techniques of dynamic light scattering, circular dichroism spectroscopy, and isothermal titration calorimetry. The results suggested different protein binding modes and stabilization abilities for the protein secondary structures from these two types of functionalized dynamic frameworks. This study provided new insights into the protein‐polymer interactions that can be beneficial for various biochemical applications.

Foliar application of pyraclostrobin alleviates oxidative stress and improves carbon assimilation in soybean

Abstract Due to its protein and oil content, soybean is an important crop in developing countries like India to combat energy-protein malnutrition. In a field study, soybean plants- foliar treated with pyraclostrobin- were evaluated for carbon fixation efficiency and antioxidant levels response. Pyraclostrobin (F500) was sprayed over soybean leaves on the tenth and twentieth day after the emergence (DAE) of seedlings at concentrations ranging from 0.05% to 1%. Parameters associated with carbon fixation, like photosystem II efficiency, gas exchange parameters, carbonic anhydrase activity, and biomass accumulation, were quantified on the 45th DAE. Antioxidant level and activity of antioxidant enzymes were also analyzed at the same stage. The amount of antioxidants like ascorbate (ASA) and the activity of antioxidant enzymes (i.e., guaiacol peroxidase, ascorbic acid peroxidase, superoxide dismutase, and catalase) decreased after pyraclostrobin application indicating alleviation of oxidative stress in treated plants as compared to control. A significant increase in the rate of photosynthesis was also recorded in the treated plants. Limiting factors of net photosynthesis like chlorophyll content, carbonic anhydrase activity, stomatal conductance, inter-cellular CO2 concentration, and transpiration rate improved after 0.1% F500 treatment. Mitigation of oxidative stress by pyraclostrobin improves the primary metabolism (fixation) in soybean, resulting in enhanced biomass accumulation.

SERRATIA MARCESCENS STRAIN FA-4 ENHANCES ZINC CONTENT IN RICE GRAINS BY ACTIVATING THE ZINC TRANSLOCATING ENZYMES

Zinc deficiency in cereal crops is a significant issue for human health. Rice, being a staple food crop, could cause severe zinc deficiency. The use of zinc-solubilizing bacteria (ZSB) is an ecological tactic to raise bioavailable zinc in the soil that may alleviate yield loss and, subsequently, enhance the nutritional value of rice. In the presented study, treating rice plants with plant growth-promoting rhizobacteria S. marcescens FA-4 along with the recommended dose of chemical Zn and half dose of chemical Zn ensued under pot and field conditions at the COMSATS University, Islamabad, Pakistan. The obtained data indicated an augmentation in rice growth, yield, and grain zinc content in response to the S. marcescens FA-4 inoculation with and without the chemical Zn application. The S. marcescens FA-4 significantly enhanced the grain zinc content (21.4–27.7 mg kg-1) under the pot and (18.7–30.1 mg kg-1) under field conditions, with 1.5 to twofold rise in superoxide dismutase (SOD) and carbonic anhydrase (CA) activity in rice compared with the control. The rice plants treated with zinc solubilizing bacteria, followed by zinc treatments gave higher grain yields of 23.4–34.1 g pot-1 and 3.2–3.6 t ha−1 in rice cultivars, Basmati 385 and Super Basmati. The S. marcescens FA-4 with a half dose of chemical Zn also increased the zinc translocation index (1.4 to 1.7) toward grains. Consistency in the performance of zinc solubilizing bacteria occurred in the pot and field conditions. Hence, a conclusion that the use of zinc solubilizing strains is an efficient approach to enhance the zinc content of rice grains and combat the problem of zinc deficiency in humans.

Hybrids of carbonic anhydrase and cyclooxygenase inhibitors attenuate cardiac hypoxic inflammatory injuries

Cardiac inflammation is easily accompanied by hypoxia, while hypoxia-induced injury and microenvironmental variations limit the efficacy of common anti-inflammatory drugs. In order to effectively attenuate myocardial injury caused by hypoxic and inflammatory injury, we designed and synthesized a kind of anti-inflammatory compounds by coupling cyclooxygenase (COX) and carbonic anhydrase (CA) inhibitors, and evaluated the activity and their mechanism in vitro and in vivo. It was found that these compounds were structurally stable and had two enzymatic inhibition activities. By inhibiting the activity of overexpressed CA under hypoxia, the acidic microenvironment can be regulated to inhibit the hypoxic injury, in which the pH-dependent primary drug resistance can be overcome to improve the anti-inflammatory effect of the COX inhibitor. Consequently, this study provides a new strategy for the treatment of cardiac inflammation accompanied by hypoxia.

Carbonic Anhydrase-Embedded Hydrogen-Bonded Organic Frameworks Coating for Facilitated Offshore CO2 Fixation.

Exhausted emission of carbon dioxide (CO2 ) from ships or offshore platforms has become one of the major contributors to global carbon emissions. Enzymes such as carbonic anhydrase (CA) have been widely used for CO2 mineralization because of their high catalytic rate. However, CA in seawater is easy to inactivate and difficult to reuse. Immobilization would be a feasible solution to address the stability issue, which, however, may cause an increase of internal diffusion resistance and reduced catalytic activity. In this regard, design of high-performance biocatalysts for acquiring high catalytic activity and stability of CA is highly desirable. Herein, a monolithic catalyst of Filler-CA@Lys-HOF-1 (FCLH) was prepared by chemical sorption of CA on the surface of the Filler followed by the coating of Lys-HOF-1. The highest catalytic activity of FCLH was obtained by regulating the amount of HOF-1 monomer added. Due to the protection of Lys-HOF-1, the FCLH showed good tolerance against acidity and salinity, which could retain about 80.2 % of the original activity after 9 h incubation in simulated seawater. The catalytic activity of FCLH could retain 85.4 % of the initial activity after 10 cycles. Hopefully, our study can provide a promising biocatalyst for CO2 mineralization, which may drive down carbon emissions when used for CO2 capture and conversion on offshore platforms.

Heterozostera nigricaulis from the south-East Pacific coast of Chile: First insights into its physiology and growth

A short stretch (27°S and 30°S) along the coast of Chile is habitat for the seagrass Heterozostera nigricaulis. The seagrass is classified as endangered and grows only clonally, but there are no data on its physiology and growth. However, this information is important to gain insights into its acclimation potential and how disturbances may affect them. We therefore studied H. nigricaulis at 27° and 30°S, and determined their growth and physiology among seasons and depths over one year. Biomass was higher at 27° than at 30°S, and was always higher in summer than in autumn and winter. Increased photosynthesis supported growth in summer, and in winter carbonic anhydrase activity was in place to maintain these evergreen meadows. Our results suggest that these seagrass meadows are adapted to local conditions, which, together with their asexual reproduction, could make them more vulnerable to disturbance. Therefore, our results serve as a basis for future studies on seagrass growth dynamics, and are important for protection and management plans.

Collateral Changes in Cell Physiology Associated with ADC-7 β-Lactamase Expression in Acinetobacter baumannii.

The ADC (AmpC) β-lactamase is universally present in the Acinetobacter baumannii chromosome, suggesting it may have a yet-to-be-identified cellular function. Using peptidoglycan composition analysis, we show that overexpressing the ADC-7 β-lactamase in A. baumannii drives changes consistent with altered l,d-transpeptidase activity. Based on this, we tested whether cells overexpressing ADC-7 would exhibit new vulnerabilities. As proof of principle, a screen of transposon insertions revealed that an insertion in the distal 3' end of canB, encoding carbonic anhydrase, resulted in a significant loss of viability when the adc-7 gene was overexpressed. A canB deletion mutant exhibited a more pronounced loss of viability than the transposon insertion, and this became amplified when cells overexpressed ADC-7. Interestingly, overexpression of the OXA-23 or TEM-1 β-lactamases also led to a pronounced loss of viability in cells with reduced carbonic anhydrase activity. In addition, we demonstrate that reduced CanB activity led to increased sensitivity to peptidoglycan synthesis inhibitors and to the carbonic anhydrase inhibitor ethoxzolamide. Furthermore, this strain exhibited a synergistic interaction with the peptidoglycan inhibitor fosfomycin and ethoxzolamide. Our results highlight the impact of ADC-7 overexpression on cell physiology and reveal that the essential carbonic anhydrase CanB may represent a novel target for antimicrobial agents that would exhibit increased potency against β-lactamase-overexpressing A. baumannii. IMPORTANCE Acinetobacter baumannii has become resistant to all classes of antibiotics, with β-lactam resistance responsible for the majority of treatment failures. New classes of antimicrobials are needed to treat this high-priority pathogen. This study had uncovered a new genetic vulnerability in β-lactamase-expressing A. baumannii, where reduced carbonic anhydrase activity becomes lethal. Inhibitors of carbonic anhydrase could represent a new method for treating A. baumannii infections.

Leveraging the concretes calcification with carbonic anhydrase produced by Alcaligenes faecalis GA(B) (Mn847724.1)

Concrete is an integrated substance that is composed of cement, water, and aggregates. The aim of this study was to biocalcify concretes with bacterial carbonic anhydrase (CA). To achieve this, a soil sample taken from a construction site in Minna Nigeria, was serially diluted and plated on nutrient agar with CaCO3 added. After 7, 14 and 28 days of curing by water immersion, the compressive strength of the concrete was determined and the effects of CA on the concretes were investigated. Alcaligenes faecalis was identified as the isolate with the better ability for CA production. The CA has a mean activity of 0.0351 U/ml, an increase in substrate concentration on CA activity from 1 to 7 mM, an optimum temperature of 50 °C and pH of 8.5. Concretes calcified with CA from A. faecalis gained a strength of 48.29 % after 28 days of curing by water immersion. The results demonstrated that CA has an enormous potential in concrete biocalcification.