Biology subjects

Lidbury, I.

Publications and source records attributed to Lidbury, I..

3 recordsLinked to original sources

bioRxiv2026

Outer membrane 'PusCD' complexes coordinate phospho(inositol)lipid utilisation in plant Bacteroidota

Gram-negative bacteria belonging to the phylum Bacteroidota are prominent and ecologically important members of host-associated microbiomes. A feature of Bacteroidota species is the presence of diverse outer membrane TonB-dependent transporter and cognate surface exposed lipoprotein (TBDT-SLP) complexes. Many 'SusCD-like' TBDT-SLPs coordinate complex carbohydrate capture from the environment. Here, we show the model soil Bacteroidota species Flavobacterium johnsoniae synthesises two TBDT-SLP complexes (named PusCD1 and PusCD2) that are essential for growth on phosphatidylinositol, a member of an abundant lipid class within plant plasma membranes, as a phosphorus source. Structural characterisation of ligand-bound PusCD1 complex from F. johnsoniae membranes reveals a new binding mechanism for organophosphorus and broadens the known functional repertoire of this class of transporters. Diverse PusCD-like complexes are widespread among plant associated Bacteroidota, pointing to a major, previously unrecognised route for the recycling of organophosphorus compounds in the rhizosphere, with potential implications for engineering microbial-mediated phosphorus recovery from organic waste streams.

microbiology↗

bioRxiv2026

Towards a comprehensive chemical and genetic tool library for rhamnogalacturonan-II oligosaccharides and exploitation

Rhamnogalacturonan-II (RG-II) is considered the most complex glycan in nature. It forms part of an intricate network of complex glycans in the plant cell wall where it plays a critical role in plant growth, development and defence. It has been identified as an important nutrient source for the human gut microbiota (HGM), a key modulator of human health and disease status. Increasing evidence also suggests that RG-II can modulate plant-microbe interactions. Given its importance and potential, detailed studies of RG-IIs structure-function relationships and metabolism are required to underpin future crop-improvement strategies and to harness its benefits for plant and human health. Progress in this field is however hampered by RG-IIs structural complexity and limited access to enabling tools, in particular chemically defined RG-II-derived oligosaccharide (CDRO) substructures. Achieving targeted, efficient, and scalable production of CDROs remains a significant challenge and is indeed one of the major reasons why RG-II and glycomic research in general, significantly lag behind genomic and proteomic research. Here, we have genetically engineered as well as screened a diverse set of genetic strains, including transposon (Tn) mutants of the prominent model human gut microbe Bacteroides thetaiotaomicron (B. theta) and its gut and plant-associated relatives for new CDRO-generating and/or RG-II-utilising strains. Several CDROs, some of which had never been produced before by any other means (including chemical synthesis), where generated and characterised by a combination of high-resolution mass spectrometry (MS), enzymatic profiling and 2D-NMR. In addition to expanding the CDRO toolbox, we identified key genetic strains that will serve as a base or platform for the production of an unprecedented amount of CDROs covering the complexity and diversity of chemical modifications in RG-II. CDROs were later exploited to gain new insights into the microbial metabolism of RG-II in the human gut, revealing key aspects of its chemical structure that drive or limit its metabolism in B. theta. Notably, we generated new evidence in support of an alternative operational paradigm for polysaccharide utilisation systems that are widespread in the Bacteroidota phylum. We confirmed the presence of pathways for the metabolism of RG-II and/or RG-II core sugars D-apiose (D-Apif), and 3-deoxy-D-manno-2-octulosonic acid (D-Kdo) in aerobic plant-associated microbes including fungi and Flavobacterium spp., highlighting their potential to be exploited as cost-effective alternatives to B. theta for the generation of CDROs.

biochemistry↗

bioRxiv2021

Phosphorus stress induces the synthesis of novel glycolipids in Pseudomonas aeruginosa that confer protection against a last-resort antibiotic

Pseudomonas aeruginosa is a nosocomial pathogen with a prevalence in immunocompromised individuals and is particularly abundant in the lung microbiome of cystic fibrosis patients. A clinically important adaptation for bacterial pathogens during infection is their ability to survive and proliferate under phosphorus (P) limited growth conditions. Here, we demonstrate that P. aeruginosa adapts to P-limitation by substituting membrane glycerophospholipids with sugar-containing glycolipids through a lipid renovation pathway involving a phospholipase and two glycosyltransferases. Combining bacterial genetics and multi-omics (proteomics, lipidomics and metatranscriptomic analyses), we show that the surrogate glycolipids monoglycosyldiacylglycerol and glucuronic acid-diacylglycerol are synthesised through the action of a new phospholipase (PA3219) and two glycosyltransferases (PA3218 and PA0842). Comparative genomic analyses revealed that this pathway is strictly conserved in all P. aeruginosa strains isolated from a range of clinical and environmental settings and actively expressed in the metatranscriptome of a cystic fibrosis patient. Importantly, this phospholipid-to-glycolipid transition comes with significant ecophysiological consequence in terms of antibiotic sensitivity. Mutants defective in glycolipid synthesis survive poorly when challenged with polymyxin B, a last-resort antibiotic for treating multi-drug resistant P. aeruginosa. Thus, we demonstrate an intriguing link between adaptation to environmental stress (nutrient availability) and antibiotic resistance, mediated through membrane lipid renovation that is an important new facet in our understanding of the ecophysiology of this bacterium in the lung microbiome of cystic fibrosis patients. ClassificationIntegrated genomics and post-genomics approaches in microbial ecology

microbiology↗