pFind Studio: a computational solution for mass spectrometry-based proteomics
2024
CELL DISCOVERY2024. J Yu et al.
Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, China
ABSTRACT:Histone variant H2A.Z is found at promoters and regulates transcription. The ATP-dependent chromatin remodeler SRCAP complex (SRCAP-C) promotes the replacement of canonical histone H2A-H2B dimer with H2A.Z-H2B dimer. Here, we determined structures of human SRCAP-C bound to H2A-containing nucleosome at near-atomic resolution. The SRCAP subunit integrates a 6-subunit actin-related protein (ARP) module and an ATPase-containing motor module. The ATPase-associated ARP module encircles half of the nucleosome along the DNA and may restrain net DNA translocation, a unique feature of SRCAP-C. The motor module adopts distinct nucleosome binding modes in the apo (nucleotide-free), ADP-bound, and ADP-BeFx-bound states, suggesting that ATPase-driven movement destabilizes H2A-H2B by unwrapping the entry DNA and pulls H2A-H2B out of nucleosome through the ZNHIT1 subunit. Structure-guided chromatin immunoprecipitation sequencing analysis confirmed the requirement of H2A-contacting ZNHIT1 in maintaining H2A.Z occupancy on the genome. Our study provides structural insights into the mechanism of H2A-H2A.Z exchange mediated by SRCAP-C.
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2024. RR Sonani et al.
Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA, 22903, USA
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Nature Communications2024. Meng, Xueming et al.
Key Laboratory of RNA Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
ABSTRACT:Radial spokes (RS) transmit mechanochemical signals between the central pair (CP) and axonemal dynein arms to coordinate ciliary motility. Atomic-resolution structures of metazoan RS and structures of axonemal complexes in ependymal cilia, whose rhythmic beating drives the circulation of cerebrospinal fluid, however, remain obscure. Here, we present near-atomic resolution cryo-EM structures of mouse RS head-neck complex in both monomer and dimer forms and reveal the intrinsic flexibility of the dimer. We also map the genetic mutations related to primary ciliary dyskinesia and asthenospermia on the head-neck complex. Moreover, we present the cryo-ET and sub-tomogram averaging map of mouse ependymal cilia and build the models for RS1-3, IDAs, and N-DRC. Contrary to the conserved RS structure, our cryo-ET map reveals the lack of IDA-b/c/e and the absence of Tektin filaments within the A-tubule of doublet microtubules in ependymal cilia compared with mammalian respiratory cilia and sperm flagella, further exemplifying the structural diversity of mammalian motile cilia. Our findings shed light on the stepwise mammalian RS assembly mechanism, the coordinated rigid and elastic RS-CP interaction modes beneficial for the regulation of asymmetric ciliary beating, and also facilitate understanding on the etiology of ciliary dyskinesia-related ciliopathies and on the ependymal cilia in the development of hydrocephalus.Radial spokes (RS) are crucial in coordinating ciliary motility. Here, authors use cryo-EM and cryo-ET to gain insight into mammalian RS divergence in ependymal cilia, RS assembly mechanism and the structure-function relationships of ciliary and flagellar axonemes.
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Nature Structural & Molecular Biology2024. D{\"u}ring, Jonas et al.
Research Group Ubiquitin Signaling Specificity, Max Planck Institute for Multidisciplinary Sciences, Gttingen, Germany
ABSTRACT:Ubiquitin ligases (E3s) are pivotal specificity determinants in the ubiquitin system by selecting substrates and decorating them with distinct ubiquitin signals. However, structure determination of the underlying, specific E3-substrate complexes has proven challenging owing to their transient nature. In particular, it is incompletely understood how members of the catalytic cysteine-driven class of HECT-type ligases (HECTs) position substrate proteins for modification. Here, we report a cryogenic electron microscopy (cryo-EM) structure of the full-length human HECT HACE1, along with solution-based conformational analyses by small-angle X-ray scattering and hydrogen-deuterium exchange mass spectrometry. Structure-based functional analyses in vitro and in cells reveal that the activity of HACE1 is stringently regulated by dimerization-induced autoinhibition. The inhibition occurs at the first step of the catalytic cycle and is thus substrate-independent. We use mechanism-based chemical crosslinking to reconstitute a complex of activated, monomeric HACE1 with its major substrate, RAC1, determine its structure by cryo-EM and validate the binding mode by solution-based analyses. Our findings explain how HACE1 achieves selectivity in ubiquitinating the active, GTP-loaded state of RAC1 and establish a framework for interpreting mutational alterations of the HACE1-RAC1 interplay in disease. More broadly, this work illuminates central unexplored aspects in the architecture, conformational dynamics, regulation and specificity of full-length HECTs.Using cryo-EM, SAXS and HDX-MS, the authors mechanistically delineate dimerization-induced autoinhibition of the HECT-type ligase HACE1 and the selectivity of the active ligase monomer for GTP-bound RAC1.
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Cell Reports2024. Prusty et al.
Department of Biochemistry 1, Biocenter, University of Wrzburg, 97074 Wrzburg, Germany
ABSTRACT:RNA helicases constitute a large protein family implicated in cellular RNA homeostasis and disease development. Here, we show that the RNA helicase IGHMBP2, linked to the neuromuscular disorder spinal muscular atrophy with respiratory distress type 1 (SMARD1), associates with polysomes and impacts translation of mRNAs containing short, GC-rich, and structured 5' UTRs. The absence of IGHMBP2 causes ribosome stalling at the start codon of target mRNAs, leading to reduced translation efficiency. The main mRNA targets of IGHMBP2-mediated regulation encode for components of the THO complex (THOC), linking IGHMBP2 to mRNA production and nuclear export. Accordingly, failure of IGHMBP2 regulation of THOC causes perturbations of the transcriptome and its encoded proteome, and ablation of THOC subunits phenocopies these changes. Thus, IGHMBP2 is an upstream regulator of THOC. Of note, IGHMBP2-dependent regulation of THOC is also observed in astrocytes derived from patients with SMARD1 disease, suggesting that deregulated mRNA metabolism contributes to SMARD1 etiology and may enable alternative therapeutic avenues.
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Nature Structural & Molecular Biology2024. Kokic, Goran et al.
Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
ABSTRACT:During transcription-coupled DNA repair (TCR), RNA polymerase II (Pol II) transitions from a transcriptionally active state to an arrested state that allows for removal of DNA lesions. This transition requires site-specific ubiquitylation of Pol II by the CRL4CSA ubiquitin ligase, a process that is facilitated by ELOF1 in an unknown way. Using cryogenic electron microscopy, biochemical assays and cell biology approaches, we found that ELOF1 serves as an adaptor to stably position UVSSA and CRL4CSA on arrested Pol II, leading to ligase neddylation and activation of Pol II ubiquitylation. In the presence of ELOF1, a transcription factor IIS (TFIIS)-like element in UVSSA gets ordered and extends through the Pol II pore, thus preventing reactivation of Pol II by TFIIS. Our results provide the structural basis for Pol II ubiquitylation and inactivation in TCR.Here the authors visualize the workings of ELOF1 in transcription-coupled DNA repair, showing that ELOF1 repositions repair factors on the surface of DNA damage-stalled RNA polymerase II to facilitate its ubiquitylation by the CRL4CSA E3 ligase and inactivation by UVSSA.
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Molecular Cell2024. Yuqiu Sun et al.
Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China
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Expert Review of Proteomics2024. Onigbinde, Sherifdeen et al.
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, USA
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Inflammation Research2024. Wen, Wei et al.
Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing, 100871, China
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Food Science and Human Wellness2024. Liu, Guirong et al.
College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, P.R.China;
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