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Ribosome subunit assembly in bacteria is a fast and efficient process. Among the nonribosomal proteins involved in ribosome biogenesis are RNA helicases. We describe ribosome biogenesis in Escherichia coli strains lacking RNA helicase DeaD (CsdA) or DbpA. Ribosome large subunit assembly intermediate particles (40S) accumulate at 25 degrees C and at 37 degrees C in the absence of DeaD but not without DbpA. 23S rRNA is incompletely processed in the 40S and 50S particles of the DeaD(-) strain. Pulse labeling showed that the 40S particles are converted nearly completely into functional ribosomes. The rate of large ribosomal subunit assembly was reduced about four times in DeaD-deficient cells. Functional activity tests of the ribosomal particles demonstrated that the final step of 50S assembly, the activation step, was affected when DeaD was not present. The results are compatible with the model that predicts multiple DeaD-catalyzed structural transitions of the ribosome large subunit assembly.
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http://dx.doi.org/10.1111/j.1742-4658.2008.06523.x | DOI Listing |
Nat Rev Mol Cell Biol
September 2025
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA.
The defining property of eukaryotic cells is the storage of heritable genetic material in a nuclear compartment. For eukaryotic cells to carry out the myriad biochemical processes necessary for their function, macromolecules must be efficiently exchanged between the nucleus and cytoplasm. The nuclear pore complex (NPC) - which is a massive assembly of ~35 different proteins present in multiple copies totalling ~1,000 protein subunits and architecturally conserved across eukaryotes - establishes a size-selective channel for regulated bidirectional transport of folded macromolecules and macromolecular assemblies across the nuclear envelope.
View Article and Find Full Text PDFJ Am Chem Soc
September 2025
Department of Chemistry, Boston University, 590 Commonwealth Ave, Boston, Massachusetts 02215, United States.
The cytosolic iron-sulfur cluster assembly (CIA) targeting complex maturates over 30 cytosolic and nuclear Fe-S proteins, raising the question of how a single complex recognizes such a diverse set of clients. The discovery of a C-terminal targeting complex recognition (TCR) peptide in up to 25% of CIA clients provided a clue to substrate specificity, yet the molecular and energetic basis for this interaction remained unresolved. By integrating computational and biochemical approaches, we show that the TCR peptide binds a conserved interface between the Cia1 and Cia2 subunits of the targeting complex, even in the absence of the Fe-S cluster.
View Article and Find Full Text PDFPLoS Pathog
September 2025
Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland.
The parasitic protozoan Trypanosoma brucei has a single mitochondrial nucleoid, anchored to the basal body of the flagellum via the tripartite attachment complex (TAC). The detergent-insoluble TAC is essential for mitochondrial genome segregation during cytokinesis. The TAC assembles de novo in a directed way from the probasal body towards the kDNA.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
September 2025
Martin A. Fisher School of Physics, Brandeis University, Waltham, MA 02453.
Programmable self-assembly has recently enabled the creation of complex structures through precise control of the interparticle interactions and the particle geometries. Targeting ever more structurally complex, dynamic, and functional assemblies necessitates going beyond the design of the structure itself, to the measurement and control of the local flexibility of the intersubunit connections and its impact on the collective mechanics of the entire assembly. In this study, we demonstrate a method to infer the mechanical properties of multisubunit assemblies using cryogenic electron microscopy (cryo-EM) and RELION's multi-body refinement.
View Article and Find Full Text PDFJ Neurochem
September 2025
Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
Memory formation involves a complex interplay of molecular and cellular processes, including synaptic plasticity mechanisms such as long-term potentiation (LTP) and long-term depression (LTD). These processes rely on activity-dependent gene expression and local protein synthesis at synapses. A central unresolved question in neuroscience is how memories can be stably maintained over time, despite the transient nature of the proteins involved in their initial encoding.
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