Protein glutathionylation is defined as a reversible, ubiquitous post-translational modification, resulting in the formation of mixed disulfides between glutathione and proteins’ cysteine residues. Glutathionylation has been implicated in several cellular mechanisms ranging from protection from oxidative stress to the control of cellular homeostasis and the cell cycle. A significant body of research has examined the multifaceted effects of this post-translational modification under physiological conditions in eukaryotes, with a particular focus on its impact on the development of various diseases in humans. In contrast, the role of glutathionylation in prokaryotic organisms remains to be extensively investigated. However, there has been a recent increase in the number of studies investigating this issue, providing details about the role of glutathione and other related thiols as post-translational modifiers of selected bacterial proteins. It can be concluded that in addition to the classical role of such thiols in protecting against cysteine oxidation and consequent protein inactivation, many more specialized roles of glutathionylation in bacterial pathogenicity, virulence, interspecies competition and survival, and control of gene expression are emerging, and new ones may emerge in the future. In this short review, we aim to summarize the current state-of-the-art in this field of research.

Protein glutathionylation is a reversible post-translational modification that involves the attachment of glutathione to cysteine residues. It plays a role in the regulation of several cellular processes and protection against oxidative damage. Glutathionylation (GS-ylation) modulates protein function, inhibits or enhances enzymatic activity, maintains redox homeostasis, and shields several proteins from irreversible oxidative stress. Aberrant GS-ylation patterns are thus implicated in various diseases, particularly those associated with oxidative stress and inflammation, such as cardiovascular diseases, neurodegenerative disorders, cancer, and many others. Research in the recent years has highlighted the potential to manipulate protein GS-ylation for therapeutic purposes with strategies that imply both its enhancement and inhibition according to different cases. Moreover, it has become increasingly evident that monitoring the GS-ylation status of selected proteins offers diagnostic potential in different diseases. In this review, we try to summarize recent research in the field with a focus on our current understanding of the molecular mechanisms related to aberrant protein GS-ylation.

Recent pandemic events have raised the attention of the public on the interactions between human and environment, with particular regard to the more and more feasible transmission to humans of micro-organisms hosted by wild-type species, due to the increasing interspecies contacts originating from human’s activities. Bats, due to their being flying mammals and their increasing promiscuity with humans, have been recognized as hosts frequently capable of transmitting disease-causing microorganisms. Therefore, it is of considerable interest and importance to have a picture as clear as possible of the microorganisms that are hosted by bats. Here we focus on our current knowledge on bats microbiota. We review the most recent literature on this subject, also in view of the bat’s body compartments, their dietary preferences and their habitat. Several pathogenic bacteria, including many carrying multidrug resistance, are indeed common guests of these small mammals, underlining the importance of preserving their habitat, not only to protect them from anthropogenic activities, but also to minimize the spreading of infectious diseases.

Nucleostemin (NS; a product of the GNL3 gene) is a nucleolar–nucleoplasm shuttling GTPase whose levels are high in stem cells and rapidly decrease upon differentiation. NS levels are also high in several solid and hematological neoplasms, including acute myeloid leukaemia (AML). While a role in telomere maintenance, response to stress stimuli and favoring DNA repair has been proposed in solid cancers, little or no information is available as to the role of nucleostemin in AML. Here, we investigate this issue via a proteomics approach. We use as a model system the OCI-AML 3 cell line harboring a heterozygous mutation at the NPM1 gene, which is the most frequent driver mutation in AML (approximately 30% of total AML cases). We show that NS is highly expressed in this cell line, and, contrary to what has previously been shown in other cancers, that its presence is dispensable for cell growth and viability. However, proteomics analysis of the OCI-AML 3 cell line before and after nucleostemin (NS) silencing showed several effects on different biological functions, as highlighted by ingenuity pathway analysis (IPA). In particular, we report an effect of down-regulating DNA repair through homologous recombination, and we confirmed a higher DNA damage rate in OCI-AML 3 cells when NS is depleted, which considerably increases upon stress induced by the topoisomerase II inhibitor etoposide. The data used are available via ProteomeXchange with the identifier PXD034012.

Coronavirus disease 2019 (COVID-19) is characterized by a broad spectrum of clinical symptoms. After acute infection, some subjects develop a post-COVID-19 syndrome known as long-COVID. This study aims to recognize the molecular and functional mechanisms that occur in COVID-19 and long-COVID patients and identify useful biomarkers for the management of patients with COVID-19 and long-COVID. Here, we profiled the response to COVID-19 by performing a proteomic analysis of lymphocytes isolated from patients. We identified significant changes in proteins involved in iron metabolism using different biochemical analyses, considering ceruloplasmin (Cp), transferrin (Tf), hemopexin (HPX), lipocalin 2 (LCN2), and superoxide dismutase 1 (SOD1). Moreover, our results show an activation of 5-lipoxygenase (5-LOX) in COVID-19 and in long-COVID possibly through an iron-dependent post-translational mechanism. Furthermore, this work defines leukotriene B4 (LTB4) and lipocalin 2 (LCN2) as possible markers of COVID-19 and long-COVID and suggests novel opportunities for prevention and treatment.

Glutathione transferases are enzymes involved in the detoxification against xenobiotics and noxious compounds. These enzymes catalyse a variety of reactions on many physiological and xenobiotic compounds using glutathione as a co-substrate. Moreover, many compounds are inhibitors of such enzymes. A wide array of biosensors based on glutathione transferases have been developed for analysing a variety of noxious compounds, as well as several biosensors devoted to the detection and quantification of glutathione and of glutathione transferases themselves. Here, we review the state of the art in this active field of research, highlighting the possible applications of such devices.

Xi class glutathione transferases (GSTs) are a recently identified group, within this large superfamily of enzymes, specifically endowed with glutathione-dependent reductase activity on glutathionyl-hydroquinone. Enzymes belonging to this group are widely distributed in bacteria, fungi, and plants but not in higher eukaryotes. Xi class GSTs are also frequently found in archaea and here we focus on the enzyme produced by the extreme haloalkaliphilic archaeon Natrialba magadii (NmGHR). We investigated its function and stability and determined its 3D structure in the apo form by X-ray crystallography. NmGHR displays the same fold of its mesophilic counterparts, is enriched in negatively charged residues, which are evenly distributed along the surface of the protein, and is characterized by a peculiar distribution of hydrophobic residues. A distinctive feature of haloalkaliphilic archaea is their preference for γ-glutamyl-cysteine over glutathione as a reducing thiol. Indeed we found that the N. magadii genome lacks a gene coding for glutathione synthase. Analysis of NmGHR structure suggests that the thiol binding site (G-site) of the enzyme is well suited for hosting γ-glutamyl-cysteine.

Glutathione transferase classical GSH conjugation activity plays a critical role in cellular detoxification against xenobiotics and noxious compounds as well as against oxidative stress. However, this feature is also exploited by cancer cells to acquire drug resistance and improve their survival. As a result, various members of the family were found overexpressed in a number of different cancers. Moreover several GST polymorphisms, ranging from null phenotypes to point mutations, were detected in members of the family and found to correlate with the onset of neuro-degenerative diseases. In the last decades, a great deal of research aimed at clarifying the role played by GSTs in drug resistance, at developing inhibitors to counteract this activity but also at exploiting GSTs for prodrugs specific activation in cancer cells. Here we summarize some of the most important achievements reached in this lively area of research.

Bats are natural reservoir hosts and sources of infection of several microorganisms, many of which cause severe human diseases. Because of contact between bats and other animals, including humans, the possibility exists for additional interspecies transmissions and resulting disease outbreaks. The purpose of this article is to supply an overview on the main pathogens isolated from bats that have the potential to cause disease in humans.

Programmed cell death is a process known to have a crucial role in many aspects of eukaryotes physiology and is clearly essential to their life. As a consequence, the underlying molecular mechanisms have been extensively studied in eukaryotes and we now know that different signalling pathways leading to functionally and morphologically different forms of death exist in these organisms. Similarly, mono-cellular organism can activate signalling pathways leading to death of a number of cells within a colony. The reason why a single-cell organism would activate a program leading to its death is apparently counterintuitive and probably for this reason cell death in prokaryotes has received a lot less attention in the past years. However, as summarized in this review there are many reasons leading to prokaryotic cell death, for the benefit of the colony. Indeed, single-celled organism can greatly benefit from multicellular organization. Within this forms of organization, regulation of death becomes an important issue, contributing to important processes such as: stress response, development, genetic transformation, and biofilm formation.

Blastoschizomyces capitatus is an uncommon, opportunistic pathogenic fungus, which causes invasive and disseminated infections. This microorganism is normally present in both environmental and normal human flora. Within a host, B. capitatus is able to grow in both unicellular yeast and multicellular filamentous growth forms. In this study, we obtained in vitro morphological conversion of B. capitatus from yeast-to-mycelial phase to investigate the presence and expression of glutathione transferase (GST) enzymes in both cell forms. A protein with GST activity using the model substrate 1-chloro-2,4-dinitrobenzene was detected in both morphologies and identified by tandem mass spectrometry as a eukaryotic elongation factor 1Bγ (eEF1Bγ) protein, a member of the GST superfamily. No significant difference in GST-specific activity and kinetic constants were observed between mycelial and yeast forms, indicating that eEF1Bγ protein did not show differential expression between the two phases.

Glutathione transferases (GSTs) are protection enzymes capable of conjugating glutathione (GSH) to toxic compounds. During evolution an important catalytic cysteine residue involved in GSH activation was replaced by serine or, more recently, by tyrosine. The utility of these replacements represents an enigma because they yield no improvements in the affinity toward GSH or in its reactivity. Here we show that these changes better protect the cell from nitric oxide (NO) insults. In fact the dinitrosyl.diglutathionyl.iron complex (DNDGIC), which is formed spontaneously when NO enters the cell, is highly toxic when free in solution but completely harmless when bound to GSTs. By examining 42 different GSTs we discovered that only the more recently evolved Tyr-based GSTs display enough affinity for DNDGIC (K-D < 10(-9) M) to sequester the complex efficiently. Ser-based GSTs and Cys-based GSTs show affinities 10(2)-10(4) times lower, not sufficient for this purpose. The NO sensitivity of bacteria that express only Cys-based GSTs could be related to the low or null affinity of their GSTs for DNDGIC. GSTs with the highest affinity (Tyr-based GSTs) are also over-represented in the perinuclear region of mammalian cells, possibly for nucleus protection. On the basis of these results we propose that GST evolution in higher organisms could be linked to the defense against NO.

Escherichia coli remains one of the most frequent causes of several common bacterial infections in humans and animals. E. coli is the prominent cause of enteritis, urinary tract infection, septicaemia and other clinical infections, such as neonatal meningitis. E. coli is also prominently associated with diarrhoea in pet and farm animals. The therapeutic treatment of E. coli infections is threatened by the emergence of antimicrobial resistance. The prevalence of multidrug-resistant E. coli strains is increasing worldwide principally due to the spread of mobile genetic elements, such as plasmids. The rise of multidrug-resistant strains of E. coli also occurs in Europe. Therefore, the spread of resistance in E. coli is an increasing public health concern in European countries. This paper summarizes the current status of E. coli strains clinically relevant in European countries. Furthermore, therapeutic interventions and strategies to prevent and control infections are presented and discussed. The article also provides an overview of the current knowledge concerning promising alternative therapies against E. coli diseases.

The p53 family apparently derives from a common ancient ancestor that dates back over a billion years, whose function was protecting the germ line from DNA damage. p63 and p73 would maintain this function through evolution while acquiring novel roles in controlling proliferation and differentiation of various tissues. p53 on the other hand would appear in early vertebrates to protect somatic cells from DNA damage with similar mechanism used by its siblings to protect germ line cells [1]. For the predominant role played by p53 mutations in cancer this was the first family member to be identified and soon became one of the most studied genes. Its siblings were identified almost 20 years later and interestingly enough their ancestral function as guardians of the germ-line was one of the last to be identified. In this review we shortly summarize the current knowledge on the structure and function of p63 and p73.

Since the initial description of apoptosis, a number of different forms of cell death have been described. In this review we will focus on classic caspase-dependent apoptosis and its variations that contribute to diseases. Over fifty years of research have clarified molecular mechanisms involved in apoptotic signaling as well and shown that alterations of these pathways lead to human diseases. Indeed both reduced and increased apoptosis can result in pathology. More recently these findings have led to the development of therapeutic approaches based on regulation of apoptosis, some of which are in clinical trials or have entered medical practice.

Glutathione transferases (GSTs) have been widely studied in Gram-negative bacteria and the structure and function of several representatives have been elucidated. Conversely, limited information is available about the occurrence, classification and functional features of GSTs both in Gram-positive bacteria and in Archaea. An analysis of 305 fully-sequenced Gram-positive genomes highlights the presence of 49 putative GST genes in the genera of both Firmicutes and Actinobacteria phyla. We also performed an analysis on 81 complete genomes of the Archaea domain. Eleven hits were found in the Halobacteriaceae family of the Euryarchaeota phylum and only one in the Crenarchaeota phylum. A comparison of the identified sequences with well-characterized GSTs belonging to both Gram-negative and eukaryotic GSTs sheds light on their putative function and the evolutionary relationships within the large GST superfamily. This analysis suggests that the identified sequences mainly cluster in the new Xi class, while Beta class GSTs, widely distributed in Gram-negative bacteria, are under-represented in Gram-positive bacteria and absent in Archaea.

Since their discovery, bacterial glutathione (GSH)transferases have been characterized in terms of their ability to catalyse a variety of different reactions on a large set of toxic molecules of xenobiotic or endobiotic origin. Furthermore the contribution of different residues in the GSH-binding site to GSH activation has been extensively investigated. Little is known, however, about the contribution to catalysis and overall stability of single residues shaping the hydrophobic co-substrate binding site (H-site). Here we tackle this problem by site-directed mutagenesis of residues facing the H-site in the bacterial beta class GSH transferase from Proteus mirabilis. We investigate the behaviour of these mutants under a variety of conditions and analyse their activity against several co-substrates, representative of the different reactions catalyzed by bacterial GSH transferases. Our work shows that mutations at the H-site can be used to modulate activity at the level of the different catalytic mechanisms operating on the chosen substrates, each mutation showing a different fingerprint. This work paves the way for future studies aimed at improving the catalytic properties of beta class GSH transferases against selected substrates for bioremediation purposes.

Bacterial glutathione transferases (GSTs) are part of a superfamily of enzymes that play a key role in cellular detoxification. GSTs are widely distributed in prokaryotes and are grouped into several classes. Bacterial GSTs are implicated in a variety of distinct processes such as the biodegradation of xenobiotics, protection against chemical and oxidative stresses and antimicrobial drug resistance. In addition to their role in detoxification, bacterial GSTs are also involved in a variety of distinct metabolic processes such as the biotransformation of dichloromethane, the degradation of lignin and atrazine, and the reductive dechlorination of pentachlorophenol. This review article summarizes the current status of knowledge regarding the functional and structural properties of bacterial GSTs.