Biology subjects

Mariano, M.

Publications and source records attributed to Mariano, M..

3 recordsLinked to original sources

bioRxiv2023

Prodomain-driven enzyme dimerization, a potent pH-dependent autoinhibition mechanism to control Plasmodium Sub1 subtilisin-like activity prior to prime merozoite egress

Malaria symptoms are associated with the asexual multiplication of Plasmodium falciparum within human red blood cells (RBC) and fever peaks coincide with the egress of daughter merozoites following the rupture of the parasitophorous vacuole (PV) and the RBC membranes (RBC). Over the last two decades it has emerged that the release of competent merozoites is tightly regulated by a complex cascade of events, including the unusual multi- step activation mechanism of the pivotal subtilisin-like protease 1 (Sub1) that takes place in three different cellular compartments and remains poorly understood. Following an initial auto- maturation in the Endoplasmic Reticulum (ER) between its pro- and catalytic domains, the Sub1 prodomain (PD) undergo further cleavages by the parasite aspartic protease plasmepsin X (PmX) within acidic secretory organelles that ultimately lead to full Sub1 activation upon discharge into the parasitophorous vacuole (PV). Here we report the crystal structure of full- length P. falciparum Sub1 (PfS1FL) and demonstrate, through structural, biochemical and biophysical studies, that the atypical Plasmodium-specific Sub1 PD directly triggers the assembly of inactive enzyme homodimers at acidic pH, whereas Sub1 is primarily monomeric at neutral pH. Our results shed new light into the finely tuned Sub1 spatiotemporal activation during secretion, particularly the different compartmentalization of PmX processing and full Sub1 activation, and uncover a robust mechanism of pH-dependent subtilisin autoinhibition involved in the tight regulation of P. falciparum merozoites egress from host infected cells. SignificanceMalaria fever spikes are due to the rupture of infected erythrocytes, allowing the egress of Plasmodium sp. merozoites and further parasite propagation. This fleeting tightly regulated event involves a cascade of enzymes, culminating with the complex activation of the subtilisin- like protease 1, Sub1. Differently than other subtilisins, Sub1 activation strictly depends upon the processing by a parasite aspartic protease within acidic merozoite secretory organelles. However, Sub1 biological activity is requested in the pH neutral parasitophorous vacuole, to prime effectors involved in the rupture of the vacuole and erythrocytic membranes. Here we show that the unusual, parasite specific Sub1 prodomain is directly responsible for its acidic- dependent dimerization and autoinhibition, required for protein secretion, before its full activation at neutral pH in a monomeric form. pH-dependent Sub1 dimerization defines a novel, essential regulatory element involved in the finely tuned spatiotemporal activation of the egress of competent Plasmodium merozoites.

microbiology↗

bioRxiv2020

IDseq - An Open Source Cloud-based Pipeline and Analysis Service for Metagenomic Pathogen Detection and Monitoring

BackgroundMetagenomic next generation sequencing (mNGS) has enabled the rapid, unbiased detection and identification of microbes without pathogen-specific reagents, culturing, or a priori knowledge of the microbial landscape. mNGS data analysis requires a series of computationally intensive processing steps to accurately determine the microbial composition of a sample. Existing mNGS data analysis tools typically require bioinformatics expertise and access to local server-class hardware resources. For many research laboratories, this presents an obstacle, especially in resource limited environments. FindingsWe present IDseq, an open source cloud-based metagenomics pipeline and service for global pathogen detection and monitoring (https://idseq.net). The IDseq Portal accepts raw mNGS data, performs host and quality filtration steps, then executes an assembly-based alignment pipeline which results in the assignment of reads and contigs to taxonomic categories. The taxonomic relative abundances are reported and visualized in an easy-to-use web application to facilitate data interpretation and hypothesis generation. Furthermore, IDseq supports environmental background model generation and automatic internal spike-in control recognition, providing statistics which are critical for data interpretation. IDseq was designed with the specific intent of detecting novel pathogens. Here, we benchmark novel virus detection capability using both synthetically evolved viral sequences, and real-world samples, including IDseq analysis of a nasopharyngeal swab sample acquired and processed locally in Cambodia from a tourist from Wuhan, China, infected with the recently emergent SARS-CoV-2. ConclusionThe IDseq Portal reduces the barrier to entry for mNGS data analysis and enables bench scientists, clinicians, and bioinformaticians to gain insight from mNGS datasets for both known and novel pathogens.

bioinformatics↗

bioRxiv2019

B-1 cell-mediated modulation of M1-macrophage profile can ameliorate microbicidal functions and disrupt the evasion mechanisms of Encephalitozoon cuniculi

Here, we have investigated the possible effect of B-1 cells on the activity of peritoneal macrophages in E. cuniculi infection. In the presence of B-1 cells, peritoneal macrophages had an M1 profile with showed increased phagocytic capacity and index, associated with the intense microbicidal activity, increased proinflammatory cytokines production and a higher percentage of apoptotic death. The absence of B-1 cells was associated with a predominance of the M2 macrophages, indicating reduced phagocytic capacity and index, microbicidal activity, proinflammatory cytokine production, and apoptotic death, but equal death rate. In addition, in the M2 macrophages, spores of phagocytic E. cuniculi with polar tubular extrusion were observed, which is an important mechanism of evasion of the immune response. The results showed the importance of B-1 cells in the modulation of macrophage function against E. cuniculi infection, increasing microbicidal activity, and reducing the fungal mechanisms involved in the evasion of the immune response.\n\nHighlightsO_LIE. cuniculi phagocytosis and microbicidal activity by macrophages increases in the presence of B-1 cells\nC_LIO_LIM1 macrophage profiles were predominant in the presence of B-1 cells\nC_LIO_LIExtrusion of the polar tubule of E. cuniculi occur inside M2 macrophages in cultures without B-1 cells\nC_LIO_LIB-1 cells derived phagocytes (B-1CDP) identified with microbicidal activity against spores of E. cuniculi\nC_LI\n\nAuthor SummaryThe adaptive immune response plays a key role against Encephalitozoon cuniculi, an opportunistic fungus for T cells immunodeficient patients. The role of B cells and antibody play in natural resistance to Encephalitozoon cuniculi remains unresolved. Previously, we demonstrated that B-1 deficient mice (XID), an important component of innate immunity, were more susceptible to encephalitozoonosis, despite the increase in the number of CD4+ and CD8+ T lymphocytes. Here we observed that the absence of B-1 cells was associated with a larger population of M2 macrophages, an anti-inflammatory profile, which had lower microbicidal activity and phagocytic E. cuniculi spores were seen with the extrusion of the polar tubule, which is an important mechanism of evasion of the immune response. The results showed the importance of B-1 cells in the modulation of macrophage function against E. cuniculi infection, increasing microbicidal activity, and reducing the fungal mechanisms involved in the evasion of the immune response.

microbiology↗