Juan Hilario Cafiero

Bio: Juan Hilario Cafiero is an academic researcher from National University of La Plata. The author has contributed to research in topics: Proteome & Sinorhizobium meliloti. The author has an hindex of 2, co-authored 5 publications receiving 20 citations.

A Bordetella pertussis MgtC homolog plays a role in the intracellular survival.

Abstract: Bordetella pertussis, the causative agent of whooping cough, has the capability to survive inside the host cells This process requires efficient adaptation of the pathogen to the intracellular environment and the associated stress Among the proteins produced by the intracellular B pertussis we identified a protein (BP0414) that shares homology with MgtC, a protein which was previously shown to be involved in the intracellular survival of other pathogens To explore if BP0414 plays a role in B pertussis intracellular survival a mutant strain defective in the production of this protein was constructed Using standard in vitro growth conditions we found that BP0414 is required for B pertussis growth under low magnesium availability or low pH, two environmental conditions that this pathogen might face within the host cell Intracellular survival studies showed that MgtC is indeed involved in B pertussis viability inside the macrophages The use of bafilomycin A1, which inhibits phagosome acidification, abolished the survival defect of the mgtC deficient mutant strain suggesting that in intracellular B pertussis the role of MgtC protein is mainly related to the bacterial adaptation to the acidic conditions found inside the of phagosomes Overall, this work provides an insight into the importance of MgtC in B pertussis pathogenesis and its contribution to bacterial survival within immune cells

The phylogeny of the genus Azohydromonas supports its transfer to the family Comamonadaceae.

Abstract: The genus Azohydromonas encompasses five validly described species belonging to the betaproteobacterial class. Recognized for their potential biotechnological uses, they were first described as belonging to the genus Alcaligenes. The phylogeny of the 16S rRNA gene of the original strains as well as newly described species led to a description of these strains within a new bacterial genus, Azohydromonas. However, the phylogenetic position of this genus remains described as part of the family Alcaligenaceae, even those some authors have placed it within the order Burkholderiales. To unravel the precise position of the genus Azohydromonas, a wide phylogenomic analysis was performed. The results of 16S rRNA gene phylogeny, as well as those obtained by the multilocus analysis of homologous proteins and overall genome relatedness indices, support the reclassification of Azohydromonas in the Rubrivivax-Ideonella lineage of the family Comamonadaceae, so the transfer of this genus is proposed.

Comparative Proteomic Analysis Revealing ActJ-Regulated Proteins in Sinorhizobium meliloti.

Abstract: To adapt to different environmental conditions, Sinorhizobium meliloti relies on finely tuned regulatory networks, most of which are unexplored to date. We recently demonstrated that deletion of the two-component system ActJK renders an acid-vulnerable phenotype in S. meliloti and negatively impacts bacteroid development and nodule occupancy as well. To fully understand the role of ActJ in acid tolerance, S. meliloti wild-type and S. meliloti ΔactJ proteomes were compared in the presence or absence of acid stress by nanoflow ultrahigh-performance liquid chromatography coupled to mass spectrometry. The analysis demonstrated that proteins involved in the synthesis of exopolysaccharides (EPSs) were notably enriched in ΔactJ cells in acid pH. Total EPS quantification further revealed that although EPS production was augmented at pH 5.6 in both the ΔactJ and the parental strain, the lack of ActJ significantly enhanced this difference. Moreover, several efflux pumps were found to be downregulated in the ΔactJ strain. Promoter fusion assays suggested that ActJ positively modulated its own expression in an acid medium but not at under neutral conditions. The results presented here identify several ActJ-regulated genes in S. meliloti, highlighting key components associated with ActJK regulation that will contribute to a better understanding of rhizobia adaptation to acid stress.

Synthesis and Study of 5[(Phenylsulfonyl)Amino]1,3,4 Thiadiazole 2 Sulfonamide as Potential Anti Pertussis Drug Using Chromatography and Spectroscopy Techniques

Abstract: Pertussis is a respiratory transmitted disease affecting approximately 23% of the worlds’ population. It is causes by Bordetella Pertussis [1-23]. The emergence of Multiple-Drug-Resistant (MDR) Pertussis has focused the attention of the scientific community thought the world on the urgent need for new anti–Pertussis drugs. In pursuit of this goal, our research efforts are directed toward the discovery of new chemical entities that are effective as anti–Pertussis drugs. During recent years, there have been intense investigations of different classes of 1,3,4-thiadiazole-2-sulfonamide compounds and derivatives such as 5-[(Phenylsulfonyl)amino]-1,3,4-thiadiazole-2-sulfonamide many of which are known to possess interesting pharmaceutical, biological, biochemical and biomedical properties suchlike anti–microbial, anti– Pertussis and anti–inflammatory activities. It should be noted that the purity of the synthesized compound was confirmed by High Performance Liquid Chromatography (HPLC) and also Thin–Layer Chromatography (TLC). Furthermore, the molecular and chemical structure of compound was characterized by 1HNMR, 13CNMR, Attenuated Total Reflectance Fourier Transform Infrared (ATR–FTIR), FT–Raman and HR Mass spectra.

Bordetella pertussis modulates human macrophage defense gene expression

Abstract: Bordetella pertussis, the etiological agent of whooping cough, still causes outbreaks. We recently found evidence that B. pertussis can survive and even replicate inside human macrophages, indicating that this host cell might serve as a niche for persistence. In this work, we examined the interaction of B. pertussis with a human monocyte cell line (THP-1) that differentiates into macrophages in culture in order to investigate the host cell response to the infection and the mechanisms that promote that intracellular survival. To that end, we investigated the expression profile of a selected number of genes involved in cellular bactericidal activity and the inflammatory response during the early and late phases of infection. The bactericidal and inflammatory response of infected macrophages was progressively downregulated, while the number of THP-1 cells heavily loaded with live bacteria increased over time postinfection. Two of the main toxins of B. pertussis, pertussis toxin (Ptx) and adenylate cyclase (CyaA), were found to be involved in manipulating the host cell response. Therefore, failure to express either toxin proved detrimental to the development of intracellular infections by those bacteria. Taken together, these results support the relevance of host defense gene manipulation to the outcome of the interaction between B. pertussis and macrophages.

Limitation of phosphate assimilation maintains cytoplasmic magnesium homeostasis.

Abstract: Phosphorus (P) is an essential component of core biological molecules. In bacteria, P is acquired mainly as inorganic orthophosphate (Pi) and assimilated into adenosine triphosphate (ATP) in the cytoplasm. Although P is essential, excess cytosolic Pi hinders growth. We now report that bacteria limit Pi uptake to avoid disruption of Mg2+-dependent processes that result, in part, from Mg2+ chelation by ATP. We establish that the MgtC protein inhibits uptake of the ATP precursor Pi when Salmonella enterica serovar Typhimurium experiences cytoplasmic Mg2+ starvation. This response prevents ATP accumulation and overproduction of ribosomal RNA that together ultimately hinder bacterial growth and result in loss of viability. Even when cytoplasmic Mg2+ is not limiting, excessive Pi uptake increases ATP synthesis, depletes free cytoplasmic Mg2+, inhibits protein synthesis, and hinders growth. Our results provide a framework to understand the molecular basis for Pi toxicity. Furthermore, they suggest a regulatory logic that governs P assimilation based on its intimate connection to cytoplasmic Mg2+ homeostasis.

Pathogenicity and virulence of Bordetella pertussis and its adaptation to its strictly human host.

Abstract: The highly contagious whooping cough agent Bordetella pertussis has evolved as a humanrestricted pathogen from a progenitor which also gave rise to Bordetella parapertussis and Bordetella bronchiseptica. While the latter colonizes a broad range of mammals and is able to survive in the environment, B. pertussis has lost its ability to survive outside its host through massive genome decay. Instead, it has become a highly successful human pathogen by the acquisition of tightly regulated virulence factors and evolutionary adaptation of its metabolism to its particular niche. By the deployment of an arsenal of highly sophisticated virulence factors it overcomes many of the innate immune defenses. It also interferes with vaccine-induced adaptive immunity by various mechanisms. Here, we review data from in vitro, human and animal models to illustrate the mechanisms of adaptation to the human respiratory tract and provide evidence of ongoing evolutionary adaptation as a highly successful human pathogen.