Molecular Microbiology

doi: 10.1111/mmi.15100pmid: N/A

Ramirez, Marcel I.

doi: 10.1111/mmi.15310pmid: 39582152

Sabatke, Bruna; Rossi, Izadora Volpato; Sana, Abel; Bonato, Leticia Bassani; Ramirez, Marcel I.

doi: 10.1111/mmi.15168pmid: 37758682

The study of host–pathogen interactions has increased considerably in recent decades. This intercellular communication has been mediated by extracellular vesicles (EVs) that play an important role during the interaction. EVs are particles of lipid bilayer and described in different types of cells, eukaryotic or prokaryotic. Depending on their biogenesis they are described as exosomes (derived from multivesicular bodies) and microvesicles (derived from the plasma membrane). The EVs carry biomolecules, including nucleic acids, lipids, and proteins that can be released or internalized by other cells in different pathways (endocytosis, macropinocytosis, phagocytosis, or membrane fusion) in the process described as uptake. The balance between biogenesis and uptake of EVs could modify physiological and pathophysiological processes of the cell. This review is focusing on the dynamic roles of release and capture of EVs during host–pathogen interaction. We also do a critical analysis of methodologies for obtaining and analyzing EVs. Finally, we draw attention to critical points to be considered in EV biogenesis and uptake studies.

Veiga, Flavia Franco; Marcomini, Emilli Karine; Salvador, Alana; Chiavelli, Lucas Ulisses Rovigatti; Barros, Isabella Letícia Esteves; Castro, Lidiane Vizioli; Lucca, Diego Luis; Ochikubo, Larissa Miwa Kikuchi; Baesso, Mauro Luciano; Pomini, Armando Mateus; Svidzinski, Terezinha Inez Estivalet; Negri, Melyssa

Salassa, Betiana Nebaí; Cueto, Juan Agustín; Vanrell, María Cristina; López, María Belén; Descoteaux, Albert; Labriola, Carlos Alberto; Romano, Patricia Silvia

doi: 10.1111/mmi.15217pmid: 38193389

Trypanosoma cruzi, the etiological agent of Chagas disease is a protozoan parasite that infects phagocytic and non‐phagocytic mammalian cells. At early stages of infection, trypomastigotes, the infective forms of this parasite, localize in a vesicular compartment called the T. cruzi parasitophorous vacuole until the exit of parasites to the host cell cytoplasm where continue their infective cycle. Rab proteins participate in the membrane traffic's molecular machinery, functioning as central regulators of vesicle recognition and transport. In previous work, we demonstrated that endocytic Rabs are key factors of the T. cruzi infection process in non‐phagocytic cells, regulating the formation and the maturation of the vacuole. In this work, we identified and characterized other molecular components of the vesicular transport pathways and their participation in the T. cruzi infection. We found that Rab9a and Rab32, two regulators of the endocytic and autophagic pathways, were actively recruited to the T. cruzi vacuoles and favored the late stages of the infective process. The recruitment was specific and dependent on T. cruzi protein synthesis. Interestingly, Rab32 association depends on the presence of Rab9a in the vacuolar membrane, while the inhibition of the cysteine‐protease cruzipain, a T. cruzi virulence factor, significantly decreases both Rab9a and Rab32 association with the vacuole. In summary, this work showed for the first time that specific molecules produced and secreted by the parasite can subvert intracellular components of host cells to benefit the infection. These new data shed light on the complex map of interactions between T. cruzi and the host cell and introduce concepts that can be useful in finding new forms of intervention against this parasite in the future.

Pandey, Meenakshi; Sarkar, Shilpa; Ghosh, Sudip K.

doi: 10.1111/mmi.15266pmid: 38654540

Entamoeba histolytica causes invasive amoebiasis, an important neglected tropical disease with a significant global health impact. The pathogenicity and survival of E. histolytica and its reptilian equivalent, Entamoeba invadens, relies on its ability to exhibit efficient motility, evade host immune responses, and exploit host resources, all of which are governed by the actin cytoskeleton remodeling. Our study demonstrates the early origin and the regulatory role of TALE homeobox protein EiHbox1 in actin‐related cellular processes. Several genes involved in different biological pathways, including actin dynamics are differentially expressed in EiHbox1 silenced cells. EiHbox1 silenced parasites showed disrupted F‐actin organization and loss of cellular polarity. EiHbox1's presence in the anterior region of migrating cells further suggests its involvement in maintaining cellular polarity. Loss of polarized morphology of EiHbox1 silenced parasites leads to altered motility from fast, directionally persistent, and highly chemotactic to slow, random, and less chemotactic, which subsequently leads to defective aggregation during encystation. EiHbox1 knockdown also resulted in a significant reduction in phagocytic capacity and poor capping response. These findings highlight the importance of EiHbox1 of E. invadens in governing cellular processes crucial for their survival, pathogenicity, and evasion of the host immune system.

Gaviraghi, Alessandro; Barletta, Ana Beatriz F.; Silva, Thiago Luiz Alves E.; Oliveira, Matheus P.; Sorgine, Marcos H. F.; Oliveira, Marcus F.

doi: 10.1111/mmi.15269pmid: 38720451

Aedes aegypti females are natural vectors of important arboviruses such as dengue, zika, and yellow fever. Mosquitoes activate innate immune response signaling pathways upon infection, as a resistance mechanism to fight pathogens and limit their propagation. Despite the beneficial effects of immune activation for insect vectors, phenotypic costs ultimately affect their fitness. However, the underlying mechanisms that mediate these fitness costs remain poorly understood. Given the high energy required to mount a proper immune response, we hypothesized that systemic activation of innate immunity would impair flight muscle mitochondrial function, compromising tissue energy demand and flight activity. Here, we investigated the dynamic effects of activation of innate immunity by intra‐thoracic zymosan injection on A. aegypti flight muscle mitochondrial metabolism. Zymosan injection significantly increased defensin A expression in fat bodies in a time‐dependent manner that compromised flight activity. Although oxidant levels in flight muscle were hardly altered, ATP‐linked respiratory rates driven by mitochondrial pyruvate+proline oxidation were significantly reduced at 24 h upon zymosan injection. Oxidative phosphorylation coupling was preserved regardless of innate immune response activation along 24 h. Importantly, rotenone‐sensitive respiration and complex I‐III activity were specifically reduced 24 h upon zymosan injection. Also, loss of complex I activity compromised ATP‐linked and maximal respiratory rates mediated by mitochondrial proline oxidation. Finally, the magnitude of innate immune response activation negatively correlated with respiratory rates, regardless of the metabolic states. Collectively, we demonstrate that activation of innate immunity is strongly associated with reduced flight muscle complex I activity with direct consequences to mitochondrial proline oxidation and flight activity. Remarkably, our results indicate a trade‐off between dispersal and immunity exists in an insect vector, underscoring the potential consequences of disrupted flight muscle mitochondrial energy metabolism to arbovirus transmission.

Silva, Michel Augusto; Izidoro, Mario Augusto; Aricó, Mirella; Juliano, Luiz; Schenkman, Sergio

doi: 10.1111/mmi.15279pmid: 38814666

Trypanosoma cruzi, a flagellated protozoan, is the causative agent of Chagas disease. The parasite has developed various mechanisms to get through its intricate life cycle and adapt to different evolutionary phases. T. cruzi proliferates in the insect vector's digestive tract as an epimastigote form, encountering fluctuating nutrient availability and oxidative stress caused by the digestion of red blood cells from the mammalian host blood meal. To unravel how the parasite's metabolism adapts to these changing conditions, we conducted an analysis of the chemical species present in epimastigote forms. This involved comparing cultured parasites with those subjected to nutritional deficiency or oxidative stress using untargeted metabolomics. We looked at 21 samples: seven biological copies of parasites that were actively growing, seven samples that were put in a medium without nutrients for 3 h, and seven samples that were treated with glucose oxidase for 30 min to make H2O2 continuously. Importantly, in all conditions, parasite viability was maintained when the samples were collected. Upon nutrient removal, we observed a substantial decrease in amino acids and carbohydrate metabolites, accompanied by the accumulation of fatty acids and steroids, with the predominance of inositol and sphingolipid metabolism, along with a simultaneous decrease in the levels of H2O2. In the presence of H2O2, a significant rise in components of the pentose pathway and specific amino acids such as methionine and serine occurred, along with pathways related to an increase in antioxidant species metabolism such as ribulose 5‐phosphate and glyceric acid. Conversely, fatty acid and steroid levels decrease. We found no common increase in metabolites or lipids. In contrast, eight species (succinic acid, glutamic acid, valine, 2‐hydroxyisocaproic acid, alanine, indolelactic acid, proline, and lanosterol) were consumed under both stresses. These findings underscore the rapid and distinct enrichment responses in amino acids, lipids, and carbohydrates required to cope with each different environmental condition. We concluded that T. cruzi presents a flexible metabolism that rapidly adapts to variable changes in the environment.

Santos Courrol, Daniella; Santos, Cassia Moreira; Chura‐Chambi, Rosa Maria; Morganti, Lígia; Avelar, Kátia Eliane Santos; Moraes Maia, Fernanda; Rodrigues‐da‐Silva, Rodrigo Nunes; Wunder, Elsio Augusto; Barbosa, Angela Silva

doi: 10.1111/mmi.15327pmid:

Fernández, Pilar; Porrini, Lucía; Pereyra, Julián Ignacio; Albanesi, Daniela; Mansilla, María Cecilia

doi: 10.1111/mmi.15320pmid: 39344851

Two‐component systems (TCSs) are vital signal transduction pathways ubiquitous among bacteria, facilitating their responses to diverse environmental stimuli. In Bacillus subtilis, the DesK histidine kinase thermosensor, together with the response regulator DesR, constitute a TCS dedicated to membrane lipid homeostasis maintenance. This TCS orchestrates the transcriptional regulation of the des gene, encoding the sole desaturase in these bacteria, Δ5‐Des. Additionally, B. subtilis possesses a paralog TCS, YvfT/YvfU, with unknown target gene(s). In this work, we show that YvfT/YvfU controls the expression of the yvfRS operon that codes for an ABC transporter. Interestingly, we found that this regulation also involves the action of DesK/DesR. Notably, opposite to des, yvfRS transcription is induced at 37°C and not at 25°C. Our in vivo and in vitro experiments demonstrate that both YvfU and DesR directly bind to the operon promoter region, with DesR exerting its control over yvfRS expression in its unphosphorylated state. Our study uncovers an intriguing case of cross‐regulation where two homologous TCSs interact closely to finely tune gene expression in response to environmental cues. These findings shed light on the complexity of bacterial signal transduction systems and their critical role in bacterial adaptability.