Activation Studies of the γ-Carbonic Anhydrases from the Antarctic Marine Bacteria Pseudoalteromonas haloplanktis and Colwellia psychrerythraea with Amino Acids and Amines

Bacterial γ-carbonic anhydrases

Carbonic anhydrases (CAs) are a ubiquitous family of zinc metalloenzymes that catalyze the reversible hydration of carbon dioxide to bicarbonate and protons, playing pivotal roles in a variety of biological processes including respiration, calcification, acid-base balance, and CO2 fixation. Recent studies have expanded the understanding of CAs, particularly the γ-class from diverse biological sources such as pathogenic bacteria, extremophiles, and halophiles, revealing their unique structural adaptations and functional mechanisms that enable operation under extreme environmental conditions. This chapter discusses the comprehensive catalytic mechanism and structural insights from X-ray crystallography studies, highlighting the molecular adaptations that confer stability and activity to these enzymes in harsh environments. It also explores the modulation mechanism of these enzymes, detailing how different modulators interact with the active site of γ-CAs. Comparative analyzes with other CA classes elucidate the evolutionary trajectories and functional diversifications of these enzymes. The synthesis of this knowledge not only sheds light on the fundamental aspects of CA biology but also opens new avenues for therapeutic and industrial applications, particularly in designing targeted inhibitors for pathogenic bacteria and developing biocatalysts for industrial processes under extreme conditions. The continuous advancement in structural biology promises further insights into this enzyme family, potentially leading to novel applications in medical and environmental biotechnology.

Comprehensive insights on environmental adaptation strategies in Antarctic bacteria and biotechnological applications of cold adapted molecules

Climate change and the induced environmental disturbances is one of the major threats that have a strong impact on bacterial communities in the Antarctic environment. To cope with the persistent extreme environment and inhospitable conditions, psychrophilic bacteria are thriving and displaying striking adaptive characteristics towards severe external factors including freezing temperature, sea ice, high radiation and salinity which indicates their potential in regulating climate change's environmental impacts. The review illustrates the different adaptation strategies of Antarctic microbes to changing climate factors at the structural, physiological and molecular level. Moreover, we discuss the recent developments in "omics" approaches to reveal polar "blackbox" of psychrophiles in order to gain a comprehensive picture of bacterial communities. The psychrophilic bacteria synthesize distinctive cold-adapted enzymes and molecules that have many more industrial applications than mesophilic ones in biotechnological industries. Hence, the review also emphasizes on the biotechnological potential of psychrophilic enzymes in different sectors and suggests the machine learning approach to study cold-adapted bacteria and engineering the industrially important enzymes for sustainable bioeconomy.

Amine- and Amino Acid-Based Compounds as Carbonic Anhydrase Activators

After being rather neglected as a research field in the past, carbonic anhydrase activators (CAAs) were undoubtedly demonstrated to be useful in diverse pharmaceutical and industrial applications. They also improved the knowledge of the requirements to selectively interact with a CA isoform over the others and confirmed the catalytic mechanism of this class of compounds. Amino acid and amine derivatives were the most explored in in vitro, in vivo and crystallographic studies as CAAs. Most of them were able to activate human or non-human CA isoforms in the nanomolar range, being proposed as therapeutic and industrial tools. Some isoforms are better activated by amino acids than amines derivatives and the stereochemistry may exert a role. Finally, non-human CAs have been very recently tested for activation studies, paving the way to innovative industrial and environmental applications.

Activation of the β-carbonic anhydrase from the protozoan pathogen Trichomonas vaginalis with amines and amino acids

We report the first activation study of the β-class carbonic anhydrase (CA, EC 4.2.1.1) encoded in the genome of the protozoan pathogen Trichomonas vaginalis, TvaCA1. Among 24 amino acid and amine activators investigated, derivatives incorporating a second carboxylic moiety, such as L-Asp, L- and D-Glu, were devoid of activating effects up to concentrations of 50 µM within the assay system, whereas the corresponding compounds with a CONH₂ moiety, i.e. L-Gln and L-Asn showed modest activating effects, with activation constants in the range of 26.9 − 32.5 µM. Moderate activation was observed with L- and D-DOPA, histamine, dopamine, serotonin, (2-Aminoethyl)pyridine/piperazine and morpholine (K_A‘s ranging between 8.3 and 14.5 µM), while the best activators were L-and D-Trp, L-and D-Tyr and 4-amino-Phe, which showed K_A‘s ranging between 3.0 and 5.1 µM. Understanding in detail the activation mechanism of β-CAs may be relevant for the design of enzyme activity modulators with potential clinical significance.

Activation studies of the β-carbonic anhydrases from Malassezia restricta with amines and amino acids

The β-carbonic anhydrase (CA, EC 4.2.1.1) from the genome of the opportunistic pathogen Malassezia restricta (MreCA), which was recently cloned and characterised, herein has been investigated for enzymatic activation by a panel of amines and amino acids. Of the 24 compounds tested in this study, the most effective MreCA activators were L-adrenaline (KA of 15 nM), 2-aminoethyl-piperazine/morpholine (KAs of 0.25-0.33 µM), histamine, L-4-amino-phenylalanine, D-Phe, L-/D-DOPA, and L-/D-Trp (KAs of 0.32 - 0.90 µM). The least effective activators were L-/D-Tyr, L-Asp, L-/D-Glu, and L-His, with activation constants ranging between 4.04 and 12.8 µM. As MreCA is involved in dandruff and seborrhoeic dermatitis, these results are of interest to identify modulators of the activity of enzymes involved in the metabolic processes of such fungi.

Activation studies of the β-carbonic anhydrases from Escherichia coli with amino acids and amines

A β-carbonic anhydrase (CA, EC 4.2.1.1) from the widespread bacterium Escherichia coli (EcoCAβ), encoded by the CynT2 gene, has been investigated for its catalytic properties and enzymatic activation by a panel of amino acids and amines. EcoCAβ showed a significant catalytic activity for the hydration of CO2 to bicarbonate and a proton, with a kinetic constant kcat of 5.3 × 105 s- and a Michaelis-Menten constant KM of 12.9 mM. The most effective EcoCAβ activators were L- and D-DOPA, L-Tyr, 4-amino-Phe, serotonin and L-adrenaline, with KAs from 2.76 to 10.7 µM. L-His, 2-pyridyl-methylamine, L-Asn and L-Gln were relatively weak activators (KAs from 36.0 to 49.5 µM). D-His, L- and D-Phe, L- and D-Trp, D-Tyr, histamine, dopamine, 2-(aminoethyl)pyridine/piperazine/morpholine, L-Asp, L- and D-Glu have KAs from 11.3 to 23.7 µM. Endogenous CA activators may play a role in bacterial virulence and colonisation of the host.

Activation of α-, β-, γ- δ-, ζ- and η- class of carbonic anhydrases with amines and amino acids: a review

Eight genetically distinct carbonic anhydrase (EC 4.2.1.1) enzyme families (α-, β-, γ- δ-, ζ-, η-, θ- and ι-CAs) were described to date. On the other hand, 16 mammalian α-CA isoforms are known to be involved in many diseases such as glaucoma, edema, epilepsy, obesity, hypoxic tumors, neuropathic pain, arthritis, neurodegeneration, etc. Although CA inhibitors were investigated for the management of a variety of such disorders, the activators just started to be investigated in detail for their in vivo effects. This review summarizes the activation profiles of α-, β, γ-, δ-, ζ- and η- CAs from various organisms (animals, fungi, protozoan, bacteria and archaea) with the most investigated classes of activators, the amines and the amino acids.

Enzymes from Marine Polar Regions and Their Biotechnological Applications

The microorganisms that evolved at low temperatures express cold-adapted enzymes endowed with unique catalytic properties in comparison to their mesophilic homologues, i.e., higher catalytic efficiency, improved flexibility, and lower thermal stability. Cold environments are therefore an attractive research area for the discovery of enzymes to be used for investigational and industrial applications in which such properties are desirable. In this work, we will review the literature on cold-adapted enzymes specifically focusing on those discovered in the bioprospecting of polar marine environments, so far largely neglected because of their limited accessibility. We will discuss their existing or proposed biotechnological applications within the framework of the more general applications of cold-adapted enzymes.

The first activation study of the β-carbonic anhydrases from the pathogenic bacteria Brucella suis and Francisella tularensis with amines and amino acids

The activation of the β-class carbonic anhydrases (CAs, EC 4.2.1.1) from the bacteria Brucella suis and Francisella tularensis with amine and amino acids was investigated. BsuCA 1 was sensitive to activation with amino acids and amines, whereas FtuCA was not. The most effective BsuCA 1 activators were L-adrenaline and D-Tyr (K_As of 0.70–0.95 µM). L-His, L-/D-Phe, L-/D-DOPA, L-Trp, L-Tyr, 4-amino-L-Phe, dopamine, 2-pyridyl-methylamine, D-Glu and L-Gln showed activation constants in the range of 0.70–3.21 µM. FtuCA was sensitive to activation with L-Glu (K_A of 9.13 µM). Most of the investigated compounds showed a weak activating effect against FtuCA (K_As of 30.5–78.3 µM). Many of the investigated amino acid and amines are present in high concentrations in many tissues in vertebrates, and their role in the pathogenicity of the two bacteria is poorly understood. Our study may bring insights in processes connected with invasion and pathogenic effects of intracellular bacteria.