Publications by authors named "Daniela Megrian"
Article Synopsis
- - The study focuses on Corynebacteriales, which have a unique outer membrane structure made of mycolic acids, and explores the mysterious 'S-layer' that enhances this membrane.
- - Researchers isolated the PS2 S-layer and used advanced 3D cryoEM techniques to reveal its structure, consisting of hexameric core units and trimeric lattice arrangements that contribute to a semipermeable membrane.
- - The findings provide insights into S-layer functions and evolution within Corynebacteriales, suggesting potential for developing bioengineered materials that utilize these membrane properties.
Article Synopsis
- MoeA (or gephyrin in higher organisms) is important for making a special molecule needed in chemical reactions, and it has another role in helping cluster receptors in brain cells.
- Scientists discovered that a copy of MoeA called Glp helps bacteria divide and that it has changed over time.
- The study showed that MoeA evolved through three big changes: it was first taken from bacteria by early eukaryotes, then had a new protein added to it, and finally learned to help organize receptors in nerve cells.
Article Synopsis
- The order Corynebacteriales contains important bacteria, including the pathogenic Mycobacterium tuberculosis and the industrially significant Corynebacterium glutamicum, both possessing complex cell walls and unique growth modes.
- Research on C. glutamicum uncovered two new members of the divisome—Glp and its receptor GlpR—highlighting their critical roles in the cell cycle alongside known proteins FtsZ and Wag31.
- The findings suggest a sophisticated protein network for regulating cell division and shape in Corynebacteriales, similar to systems found in more complex organisms, which may provide new targets for developing anti-mycobacterial treatments.
Article Synopsis
- - Actinobacteria have a unique enzyme called OdhA that combines two functions (oxidative decarboxylation and succinyl transfer) in one protein, differing from many organisms that use three separate enzymes for the 2-oxoglutarate dehydrogenase complex.
- - High-resolution structural studies (cryo-EM and crystallography) reveal that OdhA forms an 800-kDa homohexamer with a distinct three-blade propeller shape, crucial for its function.
- - The study further explores how OdhA's acyltransferase and dehydrogenase domains interact and maintain their structure, while also detailing how the signalling protein OdhI regulates the function of this complex
Article Synopsis
- Klebsiella pneumoniae (Kp) is a significant opportunistic pathogen contributing to antimicrobial resistance, making effective treatments crucial.
- Researchers have developed a new strategy for isolating anti-K phages by using capsule-deficient Kp mutants, which allows these phages to infect a broader range of Kp strains.
- This approach shows promise for overcoming limitations related to Kp's highly diverse capsules and could enhance the effectiveness of phage therapy, particularly in treating Kp infections in complex environments like the gut.
FtsEX-independent control of RipA-mediated cell separation in .
Proc Natl Acad Sci U S A
December 2022
Article Synopsis
- * RipA is a key enzyme for separating bacterial cells, and understanding its function is crucial for addressing the virulence of certain human pathogens.
- * Research on a homologue of RipA, Cg1735, shows that it is kept in an inactive state until activated by the Cg1604 protein, revealing new insights into the mechanisms of cell division and PG hydrolysis.
The division and cell wall (dcw) gene cluster in Bacteria comprises 17 genes encoding key steps in peptidoglycan synthesis and cytokinesis. To understand the origin and evolution of this cluster, we analysed its presence in over 1,000 bacterial genomes. We show that the dcw gene cluster is strikingly conserved in both gene content and gene order across all Bacteria and has undergone only a few rearrangements in some phyla, potentially linked to cell envelope specificities, but not directly to cell shape.
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- Archaea, like bacteria, divide through binary fission using FtsZ, but they lack some bacterial divisome components, only having SepF-like proteins to tether FtsZ to the membrane.
- Researchers studied the archaeon Methanobrevibacter smithii and found that SepF not only co-localizes with FtsZ during division but also helps organize the division plane and binds to membranes, inducing filament bundling.
- Structural analyses and evolutionary studies suggest that the interaction between SepF and FtsZ might have origins tracing back to the Last Universal Common Ancestor, offering new insights into cell division mechanisms in archaea and the evolutionary relationship between prokaryotic domains.
Article Synopsis
- The study investigates the evolutionary transition from Gram-positive bacteria (one membrane) to Gram-negative bacteria (two membranes) and proposes that a diderm ancestor likely existed.
- By analyzing 1,639 genomes of uncultured Firmicutes, the researchers identify a new diderm clade called Limnochordia, reinforcing the idea of independent transitions to monoderm forms.
- The findings indicate that most diderm bacteria share a common origin and that the widespread presence of diderm types suggests multi-layered cellular structures emerged early in bacterial evolution, while monoderms likely evolved through significant losses of outer membranes.
Article Synopsis
- The transition from single-membrane (monoderm) to double-membrane (diderm) cell envelopes in bacteria is a significant and unresolved question in evolutionary biology, with debates over which form is ancestral.
- Recent findings in atypical Firmicutes challenge the simple classification of bacteria into Gram-positive and Gram-negative categories, providing insights into cell envelope diversity.
- Phylogenomic analyses suggest that diderm structures may be ancestral, and that monoderm forms arose independently multiple times; research on Veillonella parvula, a diderm Firmicute, presents new opportunities to study this evolutionary transition.
Article Synopsis
- * Research using mice showed that obesity and undernourishment altered disease outcomes, with obese mice experiencing increased suffering from the infection, despite not significantly affecting the virus's replication in their blood early on.
- * The study on Mayaro virus highlighted that both obese and undernourished mice were less efficient in transmitting the virus to mosquitoes and had reduced viral fitness, indicating that nutrition plays a significant role in the dynamics of viral outbreaks.
Article Synopsis
- Chikungunya virus (CHIKV) is a mosquito-borne virus causing chikungunya fever, which can result in severe joint pain and some fatalities; recent outbreaks have been linked to the virus adapting to its mosquito hosts and poor control of these vectors.
- Researchers have developed live attenuated vaccine candidates for CHIKV using a genomic design that reduces virus mutation and maintains a reduced ability to cause disease in both mosquitoes and mammals, showing strong safety and immune response after just one dose.
- The vaccine candidates were capable of being transmitted by mosquito bites, leading to asymptomatic infections, and the extensive genomic modifications significantly lower the risk of the virus reverting back to its harmful form, making them promising options for vaccination against chikung