9SK4

Model of M. pneumoniae 30S IF3

Summary for 9SK4

• Entry DOI: 10.2210/pdb9sk4/pdb
• EMDB information: 53618
• Descriptor: 16S ribosomal RNA, Small ribosomal subunit protein uS10, Small ribosomal subunit protein uS11, ... (23 entities in total)
• Functional Keywords: 30s, ribosome, translation
• Biological source: Mycoplasmoides pneumoniae M129; More
• Total number of polymer chains: 22
• Total formula weight: 787105.97

Authors

Dobbs, J.M.,Mahamid, J. (deposition date: 2025-09-01, release date: 2026-09-23, Last modification date: 2026-10-07)

Primary citation

Dobbs, J.M.,Jensen, R.K.,Mahamid, J.
Single-cell visual proteomics of a minimal bacterium reveals structural coordination of gene expression machineries.
Cell, 2026

PubMed Abstract: Translation is a central process in gene expression. Its regulation is complex, depends on factors that include cell state and the subcellular environment, and is subject to modulation via crosstalk to processes such as transcription or translocation. Here, we used cryo-electron tomography of native and antibiotic-perturbed Mycoplasma pneumoniae cells to resolve 140 maps that recapitulate bacterial translation during the initiation, elongation, and recycling phases. We visualized multiple transcription-translation complexes, allowing us to propose a threading-based translation reinitiation mechanism and to provide structural evidence for a long-hypothesized supercomplex that coordinates transcription, translation, and membrane attachment. We resolved abundant membrane-associated large ribosomal subunits and suggest that dissociation from membranes depends on the conditional initiation of new translation, consistent with a potentially conserved mechanism in mammalian cells. This work visualizes the multilayered control of bacterial translation and demonstrates the power of in-cell structural biology to investigate regulatory circuits in gene expression.

PubMed: 42790420
DOI: 10.1016/j.cell.2026.08.054

Experimental method

ELECTRON MICROSCOPY (11.2 Å)