Biology subjects

Angelidou, G.

Publications and source records attributed to Angelidou, G..

7 recordsLinked to original sources

bioRxiv2024

The SPFH complex HflK-HflC regulates aerobic respiration in bacteria

The bacterial HflK-HflC membrane complex is a member of the highly conserved SPFH protein family, which is found throughout all domains of life and includes eukaryotic stomatins, flotillins, and prohibitins. These proteins organize cell membranes and are involved in various processes. However, the exact physiological functions of most bacterial SPFH proteins remain unclear. Here, we report that the HflK-HflC complex in Escherichia coli is required for growth under high aeration. The absence of this complex causes an aerobic growth defect due to a reduced abundance of IspG, a crucial enzyme in the isoprenoid biosynthetic pathway. This reduction leads to lower levels of ubiquinone, reduced respiration, lower ATP levels, and misregulated expression of respiratory genes. The regulation of aerobic respiration by the HflK-HflC complex resembles the mitochondrial respiratory defects caused by prohibitin mutations in mammalian and yeast cells, suggesting a functional commonality between these bacterial and eukaryotic SPFH proteins.

microbiology↗

bioRxiv2024

Enhanced metabolic entanglement emerges during the evolution of an interkingdom microbial community

Metabolic interactions are common in microbial communities and are believed to be a key factor in the emergence of complex life forms. However, while different stages of mutualism can be observed in nature, the dynamics and mechanisms underlying the gradual erosion of independence of the initially autonomous organisms are not yet fully understood. In this study, we conducted the laboratory evolution of an engineered microbial community and were able to reproduce and molecularly track its stepwise progression towards enhanced partner entanglement. The evolution of the community both strengthened the existing metabolic interactions and led to the emergence of de novo interdependence between partners for nitrogen metabolism, which is a common feature of natural symbiotic interactions. Selection for enhanced metabolic entanglement repeatedly occurred indirectly, via pleiotropies and trade-offs within cellular regulatory networks. This indicates that indirect selection may be a common but overlooked mechanism that drives the evolution of mutualistic communities.

evolutionary biology↗

bioRxiv2024

Polyketide synthase-derived sphingolipids determine microbiota-mediated protection against pathogens in C. elegans

Protection against pathogens is a major function of the gut microbiota. Although bacterial natural products have emerged as crucial components of host-microbiota interactions, their exact role in microbiota-mediated protection is largely unexplored. We addressed this knowledge gap with the nematode Caenorhabditis elegans and its microbiota isolate Pseudomonas fluorescens MYb115 that is known to protect against Bacillus thuringiensis (Bt) infection. We find that MYb115-mediated protection depends on sphingolipids that are derived from an iterative type I polyketide synthase (PKS), thereby describing a noncanonical pathway of bacterial sphingolipid production. We provide evidence that MYb115-derived sphingolipids affect C. elegans tolerance to Bt infection by altering host sphingolipid metabolism. This work establishes sphingolipids as structural outputs of bacterial PKS and highlights the role of microbiota-derived sphingolipids in host protection against pathogens.

molecular biology↗

bioRxiv2024

MprF-mediated immune evasion is necessary for Lactiplantibacillus plantarum resilience in Drosophila gut during inflammation

BackgroundMultiple peptide resistance factor (MprF) confers resistance to cationic antimicrobial peptides (AMPs) in several pathogens, thereby enabling evasion of the host immune response. While MprF has been proven to be crucial for the virulence of various pathogens, its role in commensal gut bacteria remains uncharacterized. To close this knowledge gap, we used a common gut commensal of animals, Lactiplantibacillus plantarum, and its natural host, the fruit fly Drosophila melanogaster, as an experimental model to investigate the role of MprF in commensal-host interactions. ResultsThe L. plantarum {Delta}mprF mutant that we generated exhibited deficiency in the synthesis of lysyl-phosphatidylglycerol (Lys-PG), resulting in increased negative cell surface charge and increased susceptibility to AMPs. Susceptibility to AMPs had no effect on {Delta}mprF mutants ability to colonize guts of uninfected flies. However, we observed significantly reduced abundance of the {Delta}mprF mutant after infection-induced inflammation in the guts of wild-type flies but not flies lacking AMPs. These results demonstrate that host AMPs reduce the abundance of the {Delta}mprF mutant during infection. We found in addition that the {Delta}mprF mutant compared to wild-type L. plantarum induces a stronger intestinal immune response in flies due to the increased release of immunostimulatory peptidoglycan fragments, indicating an important role of MprF in promoting host tolerance to commensals. ConclusionOverall, our results demonstrate that MprF, besides its well-characterized role in pathogen immune evasion and virulence, is also an important resilience factor in maintaining stable microbiota-host interactions during intestinal inflammation.

microbiology↗

bioRxiv2023

Ketosynthase engineering enhances activity and shifts specificity towards non-native extender units in type I linear polyketide synthase

Engineering modular type I polyketide synthases (PKS) for the targeted incorporation of non-natural substrates to create variations in the polyketide backbone is a long-standing goal of PKS research. Thus far, most approaches focused on engineering the acyltransferase domain (AT) of PKS, whereas the effects of other ubiquitous domains such as the ketosynthase domain (KS) have received much less attention. In this work, we investigated the effects of thirteen active site substitutions in the module 3 KS (KS3) of the 6-deoxyerythronolide B synthase (DEBS) on incorporation of non-natural extender units in vitro. Using a truncated and a complete DEBS assembly line, we show that substitutions of F263 in KS3 invert specificity up to 1,250-fold towards incorporation of non-natural extender units in the terminal position. In contrast, substitutions of I444 in KS3 show up to 8-fold increased production of 6-deoxyerythonolide B (6-dEB) analogues with non-natural extender units at internal positions. The latter notably without compromising overall productivity of the assembly line. Our study further elucidates the underlying mechanisms for these different behaviors, highlighting the potential of KS engineering for the production of designer polyketides in the future.

biochemistry↗

bioRxiv2022

Pilotins are mobile T3SS components involved in assembly and substrate specificity of the bacterial type III secretion system

In animal pathogens, assembly of the type III secretion system injectisome requires the presence of so-called pilotins, small lipoproteins that assist the formation of the secretin ring in the outer membrane. Using a combination of functional assays, interaction studies, proteomics, and live-cell microscopy, we determined the contribution of the pilotin to the assembly, function, and substrate selectivity of the T3SS and identified potential new downstream roles of pilotin proteins. In absence of its pilotin SctG, Yersinia enterocolitica forms few, largely polar injectisome sorting platforms and needles. In line, most export apparatus subcomplexes are mobile in these strains, suggesting the absence of fully assembled injectisomes. Remarkably, while absence of the pilotin all but prevents export of early T3SS substrates, such as the needle subunits, it has little effect on secretion of late T3SS substrates, including the virulence effectors. We found that pilotins transiently interact with other injectisome components such as the secretin in the outer membrane, but mostly form transient mobile clusters in the bacterial membrane, which do not colocalize with assembled injectisomes. Together, these findings provide a new view on the role of pilotins during and after assembly of type III secretion injectisomes.

microbiology↗

bioRxiv2021

AdipoAtlas: A Reference Lipidome for Human White Adipose Tissue

Obesity, characterized by expansion and metabolic dysregulation of white adipose tissue (WAT), has reached pandemic proportions and acts as a primer for a wide range of metabolic disorders. Remodelling of WAT lipidome in obesity and associated comorbidities can explain disease etiology and provide valuable diagnostic and prognostic markers. To support understanding of WAT lipidome remodelling at the molecular level, we performed in-depth lipidomics profiling of human subcutaneous and visceral WAT of lean and obese individuals. Tissue-tailored preanalytical and analytical workflows allowed accurate identification and semi-absolute quantification of 1636 and 737 lipid molecular species, respectively, and summarized here in a form of human WAT reference lipidome. Deep lipidomic profiling allowed to identify main lipid (sub)classes undergoing depot/phenotype specific remodelling. Furthermore, previously unanticipated diversity of WAT ceramides was uncovered. AdipoAtlas reference lipidome will serve as a data-rich resource for the development of WAT-specific high-throughput methods and as a scaffold for systems medicine data integration.

biochemistry↗