Project description:We uncover an enzymatic program that controls intracellular amyloidogenesis. ePAT confirmation of starRNA using long-read sequencing.
Project description:We uncover an enzymatic program that controls intracellular amyloidogenesis. FLAM-seq. analysis of purified Amyloid bodies identifies starRNA.
Project description:Amyloids interact with plasma membranes. Extracellular amyloids cross the plasma membrane barrier. Internalized extracellular amyloids are reported to trigger amyloidogenesis of endogenous proteins in recipient cells. To what extent these extracellular and intracellular amyloids perturb the plasma membrane proteome is not investigated. Using α-Synuclein as a model amyloid protein, we performed membrane shaving followed by mass spectrometry experiment to identify the conformational changes in the cell surface proteins after extracellular amyloid challenge. We also performed membrane proteomics after the biogenesis of intracellular α-Synuclein amyloids. Our results suggest that promiscuous interaction with extracellular amyloids stochastically alter the conformation of plasma membrane proteins. This affects the biological process through the plasma membrane and result in loss in cell viability. Cells that survive the extracellular amyloid shock can grow normally and gradually develop intracellular amyloids which do not directly impact the plasma membrane proteome and associated biological processes. Thus, α-Synuclein amyloids can damage the plasma membrane and related processes only during cell to cell transfer and not during their intracellular biogenesis.
Project description:200,000 worms were grown to the young adult stage, collected, and washed. Worms were homogenized in lysis buffer (10mM Tris, pH 7.5, 138mM NaCl, 2mM CaCl2, and 0.1% NP-40). After homogenization, 125U/mL Benzonase nuclease was added to homogenates and samples were incubated for 30 mins at room temperature with gentle rocking. Samples were spun at 21,000g for 5 mins, followed by resuspension of the pellet in lysis buffer. Soluble proteins were removed from the pellet with repeated washes in lysis buffer until A280 of the supernatant was equal to A280 of lysis buffer. Resulting pellet was resuspended in ddH2O, spun at 21,000g for 5 mins, and supernatant was transferred to a collection tube. Water resuspensions and recoveries were continued until A280 of H2O supernatants was 0. Recovered water washes were pooled and amyloids salted out by adding NaCl to 200mM final concentration, followed by 1-3 days incubation at 4oC. Precipitated amyloids were recovered by centrifuging at 21,000g for 30 mins, followed by resuspension in 50-100uL ddH2O. Amyloids were digested (trypsin and chymotrypsin) and prepared for mass spectrometry as described in the methods files.
Project description:Cells respond to stress by blocking translation, rewiring metabolism, and forming transient mRNP assemblies called stress granules (SGs). After stress release, re-establishing homeostasis requires energy-consuming processes. However, the molecular mechanisms whereby cells restore energy production to disassemble SGs and reinitiate growth after stress remain poorly understood. Here we show that, upon stress, the ATP-producing enzyme Cdc19 forms inactive amyloids, and that their rapid re-solubilization is essential to restore energy production and SG disassembly. Cdc19 re-solubilization is initiated by the glycolytic metabolite fructose-1,6-bisphosphate (FBP), which directly binds Cdc19 amyloids and facilitates conformational changes that allow Hsp104 and Ssa2 chaperone recruitment. FBP then promotes Cdc19 tetramerization and activity, which together with trehalose breakdown boosts glycolysis to further enhance SG disassembly. Together, these results provide a molecular mechanism protecting cells during stress by directly coupling metabolism and ATP production with SG dynamics via regulation of Cdc19 amyloids.
Project description:Coupling molecular biology to high throughput sequencing has revolutionized the study of biology. Molecular genomics techniques are continually refined to provide higher resolution mapping of nucleic acid interactions and nucleic acid structure. These assays are converging on single-nucleotide resolution measurements, but the sequence preferences of molecular biology enzymes can interfere with the accurate interpretation of the data. Enzymatic sequence preferences manifest more prominently as the resolution of these assays increase. We developed seqOutBias to seek out enzymatic sequence bias from experimental data and scale individual sequence reads to correct the bias. We show that this software efficiently and successfully corrects the sequence bias resulting from DNase-seq, TACh-seq, ATAC-seq, MNase-seq, and PRO-seq data.