Classification of Single Particles from Human Cell Extract Reveals Distinct Structures
Ontology highlight
ABSTRACT:
INSTRUMENT(S): Orbitrap Fusion
ORGANISM(S): Homo Sapiens (ncbitaxon:9606)
SUBMITTER: 
David Taylor
PROVIDER: MSV000082436 | MassIVE | Mon Jun 04 09:53:00 BST 2018
SECONDARY ACCESSION(S): PXD010026
REPOSITORIES: MassIVE
Similar Datasets
Project description:Multi-protein complexes are necessary for nearly all cellular processes, and understanding their structure is required for elucidating their function. Current high-resolution strategies in structural biology are effective but lag behind other fields (e.g., genomics and proteomics) due to their reliance on purified samples rather than heterogeneous mixtures. Here, we present a method combining single-particle analysis by electron microscopy with protein identification by mass spectrometry to structurally characterize macromolecular complexes from human cell extract. We identify HSP60 through two-dimensional classification and obtain three-dimensional structures of native proteasomes directly from ab initio classification of a heterogeneous mixture of protein complexes. In addition, we reveal an ∼1-MDa-size structure of unknown composition and reference our proteomics data to suggest possible identities. Our study shows the power of using a shotgun approach to electron microscopy (shotgun EM) when coupled with mass spectrometry as a tool to uncover the structures of macromolecular machines.
| S-EPMC6109231 | biostudies-literature
Project description: Not available
| EMPIAR-10998 | biostudies-other
Project description:Double-stranded DNA is a dynamic molecule whose structure can change depending on conditions. While there is consensus in the literature about many structures DNA can have, the state of highly-stretched DNA is still not clear. Several groups have shown that DNA in the torsion-unconstrained B-form undergoes an "overstretching" transition at a stretching force of around 65 pN, which leads to approximately 1.7-fold elongation of the DNA contour length. Recent experiments have revealed that two distinct structural transitions are involved in the overstretching process: (i) a hysteretic "peeling" off one strand from its complementary strand, and (ii) a nonhysteretic transition that leads to an undetermined DNA structure. We report the first simultaneous determination of the entropy (?S) and enthalpy changes (?H) pertaining to these respective transitions. For the hysteretic peeling transition, we determined ?S ? 20 cal/(K.mol) and ?H ? 7 kcal/mol. In the case of the nonhysteretic transition, ?S ? -3 cal/(K.mol) and ?H ? 1 kcal/mol. Furthermore, the response of the transition force to salt concentration implies that the two DNA strands are spatially separated after the hysteretic peeling transition. In contrast, the corresponding response after the nonhysteretic transition indicated that the strands remained in close proximity. The selection between the two transitions depends on DNA base-pair stability, and it can be illustrated by a multidimensional phase diagram. Our results provide important insights into the thermodynamics of DNA overstretching and conformational structures of overstretched DNA that may play an important role in vivo.
| S-EPMC3361402 | biostudies-literature
Project description:Previously, we showed that high-resolution template matching can localize ribosomes in two-dimensional electron cryo-microscopy (cryo-EM) images of untilted Mycoplasma pneumoniae cells with high precision (Lucas et al., 2021). Here, we show that comparing the signal-to-noise ratio (SNR) observed with 2DTM using different templates relative to the same cellular target can correct for local variation in noise and differentiate related complexes in focused ion beam (FIB)-milled cell sections. We use a maximum likelihood approach to define the probability of each particle belonging to each class, thereby establishing a statistic to describe the confidence of our classification. We apply this method in two contexts to locate and classify related intermediate states of 60S ribosome biogenesis in the Saccharomyces cerevisiae cell nucleus. In the first, we separate the nuclear pre-60S population from the cytoplasmic mature 60S population, using the subcellular localization to validate assignment. In the second, we show that relative 2DTM SNRs can be used to separate mixed populations of nuclear pre-60S that are not visually separable. 2DTM can distinguish related molecular populations without the need to generate 3D reconstructions from the data to be classified, permitting classification even when only a few target particles exist in a cell.
| S-EPMC9444246 | biostudies-literature
Project description:Analysis of 3 subsets of primary human CD4+ T cells (naive, CM, EM) stimulated with anti-CD3, anti-CD28 and PD-L1/PD-L2 for 18 hours. we show that naive, EM, and CM T cell subsets had distinct gene expression profiles following PD-1 ligation.
2021-07-01 | GSE174860 | GEO
Project description:We used 4C sequencing technology for high-throughput profiling of HHV6A integration in both HEK293T cells and SMC cells. We identified genome-wide host-virus and virus-virus interactions profiles.
2020-12-09 | GSE162821 | GEO
Project description:MK: MK-801. Young male C57BL/6J mice received an injection of MK-801 (300 micro-g per g body weight). RNA from control mice were extracted 1hr, 2hr, 4hr, and 6hr after MK experimental mice received their last shock treatment. MK C+S: MK-801 & Context + Shock: Young male C57BL/6J mice received an injection of MK-801 (300 micro-g per g body weight) 1 h prior to contextual fear conditioning that consisted of: Placement into a novel spatial context for 2 min. After 2 min, a 1 sec (0.5 mA) shock was administered through a floor grid. The 2 min-1 sec shock paradigm was repeated for a total of 3 shocks. 1 min after the last shock, animals were removed to their homecage. RNA was extracted 1hr, 2hr, 4hr, and 6hr after the last shock treatment. Keywords: time-course
2003-02-27 | GSE318 | GEO
Project description:MK: MK-801. Young male C57BL/6J mice received an injection of MK-801 (300 micro-g per g body weight). RNA from control mice were extracted 1hr, 2hr, 4hr, and 6hr after MK experimental mice received their last shock treatment. MK C+S: MK-801 & Context + Shock: Young male C57BL/6J mice received an injection of MK-801 (300 micro-g per g body weight) 1 h prior to contextual fear conditioning that consisted of: Placement into a novel spatial context for 2 min. After 2 min, a 1 sec (0.5 mA) shock was administered through a floor grid. The 2 min-1 sec shock paradigm was repeated for a total of 3 shocks. 1 min after the last shock, animals were removed to their homecage. RNA was extracted 1hr, 2hr, 4hr, and 6hr after the last shock treatment. Keywords: time-course
2003-02-27 | GSE317 | GEO
Project description:Three human cell lines, K562, HEK293T and A431, and one murine cell line, L929, are mixed with equal proportion in two experiments. One mixture, named Mix3, consists of K562, HEK293T and L929. The other, named Mix4, consists of K562, HEK293T, A431 and L929. These cell lines were processed with the Singleron GEXSCOPETM protocol using GEXSCOPETM Single Cell RNA Library Kit (Singleron) and sequenced on an Illumina Xten. FASTQ data were preprocessed using fastp and STAR.
2019-11-27 | GSE128982 | GEO
