Biology subjects

Moura, I.

Publications and source records attributed to Moura, I..

5 recordsLinked to original sources

bioRxiv2024

Shifting Routes: Plant Specific Insert trafficking and function in Arabidopsis seedlings under abiotic stress

Due to plants inability to escape adverse conditions, they must adapt and adjust their endomembrane system through protein sorting and distribution. Cardosins A and B are key models for studying intracellular trafficking. They are aspartic proteinases in thistle flowers that mediate different vacuolar pathways despite sharing high sequence similarity, and both are responsive to stress conditions. The Plant Specific Insert (PSI) is a 100 amino acid domain found in these proteins. It is known that stress can impact protein sorting, shifting it from the conventional pathway (ER-Golgi) to a Golgi-independent route. In this work we assessed changes in the expression and localization of PSI from Cardosin B (PSI B) in Arabidopsis plants overexpressing PSI B-mCherry submitted to different abiotic stress conditions (saline, hydric, oxidative, metals). Aside from potential PSI B localization changes, we focused on characterizing the homozygous line, alongside assessing several biometric parameters and biochemical endpoints. The results revealed that the PSI B line responded differently depending on the stress conditions. Biometric and biochemical analyses emphasized the roles of PSI B in enhancing plant fitness and supporting adaptation to abiotic stress. Besides, confocal microscopy allowed us to find PSI B accumulation in Endoplasmic Reticulum-derived vesicles (ER bodies), indicating a shift from the common PSI B-mediated route. These findings underscore the role of PSI B in enhancing plant fitness and adaptation to abiotic stress through altered protein trafficking. HighlightPSI B has an active role in enhancing plant fitness, revealing its value in adaptation and tolerance to abiotic stress by adjusting its localization and trafficking under challenging environments.

plant biology↗

bioRxiv2024

Effect of pH on the thermostability and redox properties of cytochrome c552 from Wolinella succinogenes

Cytochrome c552 from Wolinella succinogenes is one of the few examples of a low reduction potential class I c-type cytochrome with a mixture of high/low spin state populations observed in its visible spectrum. Analysis of its structural model suggests that the heme is Met/His coordinated and highly solvent-exposed. This supports the hypothesis that it is the solvent accessibility of the propionate groups that controls the reduction potential of small c-type cytochromes. The visible spectra obtained at different pH values reveal the presence of a protonable group with a pKa of 7.3, which also influences the reduction potential of this small cytochrome c552 (Em0 of 97 {+/-} 5 mV, pH 7.0) and can be either an H2O/OH- group distantly coordinating the heme iron, or one of the propionate groups. The thermostability of cytochrome c552 has been studied by circular dichroism and differential scanning calorimetry, indicating a highly stable protein at pH 5-7 (90 {degrees}C to 77 {degrees}C).

biochemistry↗

bioRxiv2022

MiGut: a scalable in vitro platform for simulating the human gut microbiome - development, validation, and simulation of antibiotic induced dysbiosis

In vitro models of the human colon have been used extensively in developing understanding of the human gut microbiome and how internal and external factors affect the residing bacterial populations. Such models can be highly predictive of in vivo effects of antibiotics, and indeed more so than animal models. The complexity required by current in vitro models to closely mimic the physiology of the colon poses practical limits on their scalability. MiGut allows considerable expansion of model runs, increasing the capacity to test reproducibility or parameters under investigation. The MiGut platform has been assessed against a well-studied triple-stage chemostat model in a demanding nine-week study, with exposure to multiple antibiotics inducing a state of dysbiosis in the microbiome. A good correlation is found, both between individual MiGut models and against the triple-stage chemostat. Together with high-throughput molecular techniques for sample analysis, it is now conceivable that tens of in vitro models could be run simultaneously, allowing complex microbiome-xenobiotic interactions to be explored in far greater detail. MiGut is a unique platform whereby multiple colonic models can be run simultaneously with minimal added resource and complexity to support our understanding of the cause-effect relationships that govern the gut microbiome. This model system expands the capacity to generate clinically relevant data that can optimize interventions which target the gut microbiome directly or indirectly.

microbiology↗

bioRxiv2021

Insights into the regulatory mechanisms of Clostridioides difficile biofilm formation

Mucosal biofilms play an important role in intestinal health; however, the mucosal bacterial community has been implicated in persistent infections. Clostridioides difficile is an important nosocomial pathogen, with an unacceptable high rate of recurrence following antibiotic treatment. As C. difficile is a known biofilm producer, a property which may contribute to this suboptimal therapeutic response, we have investigated the transcriptional changes and regulatory pathways during the transition from planktonic to biofilm mode of growth. Widespread metabolic reprogramming during biofilm formation was detected, characterised by an increased usage of glycine metabolic pathways to yield key metabolites, which are used for energy production and synthesis of short chain fatty acids. We detected the expression of 107 small non-coding RNAs that appear to, in some part, regulate these pathways; however, 25 of these small RNAs were specifically expressed during biofilm formation, indicating they may play a role in regulating biofilm-specific genes. Similar to Bacillus subtilis, biofilm formation is a multi-regulatory process and SinR negatively regulates biofilm formation independently of other known mechanisms. This comprehensive analysis furthers our understanding of biofilm formation in C. difficile, identifies potential targets for anti-virulence factors, and provides evidence of the link between metabolism and virulence traits.

microbiology↗

bioRxiv2021

Pilot study: Trehalose-induced remodelling of the human microbiota affects Clostridioides difficile infection outcome in an in vitro colonic model

Within the human intestinal tract, dietary, microbial- and host-derived compounds are used as signals by many pathogenic organisms, including Clostridioides difficile. Trehalose has been reported to enhance virulence of certain C. difficile ribotypes; however, such variants are widespread and not correlated with clinical outcomes for patients suffering from C. difficile infection (CDI). Here, we make preliminary observations to how to trehalose supplementation affects the microbiota in an in vitro model and show that trehalose can reduce the outgrowth of C. difficile, preventing simulated CDI. Three clinically reflective human gut models simulated the effects of sugar (trehalose or glucose) or saline ingestion on the microbiota. Models were instilled with sugar or saline and further exposed to C. difficile spores. The recovery of the microbiota following antibiotic treatment and CDI induction was monitored in each model. The human microbiota remodeled to utilise the bioavailable trehalose. Clindamycin induction caused simulated CDI in models supplemented with either glucose or saline; however, trehalose supplementation did not result in CDI, although limited spore germination did occur. The absence of CDI in trehalose model was associated with enhanced abundances of Finegoldia, Faecalibacterium and Oscillospira, and reduced abundances of Klebsiella and Clostridium spp., compared with the other models. Functional analysis of the microbiota in the trehalose model revealed differences in the metabolic pathways, such as amino acid metabolism, which could be attributed to prevention of CDI. Our data show that trehalose supplementation remodelled the microbiota, which prevented simulated CDI, potentially due to enhanced recovery of nutritionally competitive microbiota against C. difficile.

microbiology↗