Project description:Hydrogen/deuterium exchange (HDX) methods for studying protein dynamics would benefit from millisecond-scale incubations to probe intrinsically disordered proteins, highly dynamic regions and conformation changes. Here we investigate droplet microfluidics for rapid mixing to trigger D2O labelling, uniform incubations and rapid droplet merging for acid quenching in advance of mass spectrometry. A surfactant-free merging approach combining expansion elements for synchronised droplet collision proved robust. The high diffusive flux of D2O and protons enable microsecond mixing to trigger and arrest D2O labelling, respectively, affording the possibility of single millisecond incubations. Droplet HDX processors were used to measure the fast uptake characteristics of a model peptide. Forward exchange measurements demonstrate D2O labelling to be the rate-limiting step, in essence defining 10 milliseconds as the minimum practical incubation time for proteins in typical physiological conditions. With the ability to access millisecond time scales the fast dynamics of calmodulin, a model of calcium-triggered allostery with rapid conformational switching, was investigated. At 10 milliseconds, we could observe significant deuterium uptake within the well-defined EF-hand motifs (Ca2+ binding sites). These findings demonstrate millisecond HDX enabled by droplet microfluidics allows areas of heightened plasticity to be detected within a stably folded protein. Associated dataset: PXD077479
Project description:Hydrogen/deuterium exchange (HDX) methods for studying protein dynamics would benefit from millisecond-scale incubations to probe intrinsically disordered proteins, highly dynamic regions and conformation changes. Here we investigate droplet microfluidics for rapid mixing to trigger D2O labelling, uniform incubations and rapid droplet merging for acid quenching in advance of mass spectrometry. A surfactant-free merging approach combining expansion elements for synchronised droplet collision proved robust. The high diffusive flux of D2O and protons enable microsecond mixing to trigger and arrest D2O labelling, respectively, affording the possibility of single millisecond incubations. Droplet HDX processors were used to measure the fast uptake characteristics of a model peptide. Forward exchange measurements demonstrate D2O labelling to be the rate-limiting step, in essence defining 10 milliseconds as the minimum practical incubation time for proteins in typical physiological conditions. With the ability to access millisecond time scales the fast dynamics of calmodulin, a model of calcium-triggered allostery with rapid conformational switching, was investigated. At 10 milliseconds, we could observe significant deuterium uptake within the well-defined EF-hand motifs (Ca2+ binding sites). These findings demonstrate millisecond HDX enabled by droplet microfluidics allows areas of heightened plasticity to be detected within a stably folded protein.
Project description:Droplet microfluidics-based iX-seq uncovers cross-feeding interactions between Phascolarctobacterium faecium and Eubacterium limosum in the gut microbiota
Project description:Cell-cell interactions are important to numerous biological systems, including tissue microenvironments, the immune system, and cancer. However, current methods for studying cell combinations and interactions are limited in scalability, allowing just hundreds to thousands of multi-cell assays per experiment; this limited throughput makes it difficult to characterize interactions at biologically relevant scales. Here, we describe a new paradigm in cell interaction profiling that allows accurate grouping of cells and characterization of their interactions for tens to hundreds of thousands of combinations. Our approach leverages high throughput droplet microfluidics to construct multicellular combinations in a deterministic process that allows inclusion of programmed reagent mixtures and beads. The combination droplets are compatible with common manipulation and measurement techniques, including imaging, barcode-based genomics, and sorting. We demonstrate the approach by using it to enrich for CAR-T cells that activate upon incubation with target cells, a bottleneck in the therapeutic T cell engineering pipeline. The speed and control of our approach should enable valuable cell interaction studies.
Project description:Mucus forms a critical barrier against enteric pathogens like Salmonella enterica serovar Typhimurium. While in vivo studies indicate that secreted, gel-forming mucins and specifically Core 3 glycosylation are protective against S. Typhimurium, the molecular mechanisms involved remain unclear. Here, we measure gene expression changes in Salmonella enterica serovar Typhimurium LT2 following growth in SPI-1 inducing medium (LB + 0.3M NaCl) with or without purified MUC2 (0.1%, w/v), MUC2 glycans (0.1%, w/v), a pool of monosaccharide components comprised of D-galactose, D-GalNAc, D-GlcNAc, D-fuc, and Neu5Ac (0.1%, w/v), or specific individual mucin sugars, namely N-acetyl galactosamine (GalNAc) (0.2%, w/v) and N-acetyl glucosamine (GlcNAc) (0.2%, w/v). Notably, we find MUC2, MUC2 glycans, and to a lesser extent,D-GalNAc and D-GlcNAc downregulate SPI-1 gene expression.