ジャーナル: Nat Struct Mol Biol / 年: 2025 タイトル: Structural insights into context-dependent inhibitory mechanisms of chloramphenicol in cells. 著者: Liang Xue / Christian M T Spahn / Magdalena Schacherl / Julia Mahamid / 要旨: Ribosome-targeting antibiotics represent an important class of antimicrobial drugs. Chloramphenicol (Cm) is a well-studied ribosomal peptidyl transferase center (PTC) binder and growing evidence ...Ribosome-targeting antibiotics represent an important class of antimicrobial drugs. Chloramphenicol (Cm) is a well-studied ribosomal peptidyl transferase center (PTC) binder and growing evidence suggests that its inhibitory action depends on the sequence of the nascent peptide. How such selective inhibition on the molecular scale manifests on the cellular level remains unclear. Here, we use cryo-electron tomography to analyze the impact of Cm inside the bacterium Mycoplasma pneumoniae. By resolving the Cm-bound ribosomes to 3.0 Å, we elucidate Cm's coordination with natural nascent peptides and transfer RNAs in the PTC. We find that Cm leads to the accumulation of a number of translation elongation states, indicating ongoing futile accommodation cycles, and to extensive ribosome collisions. We, thus, suggest that, beyond its direct inhibition of protein synthesis, the action of Cm may involve the activation of cellular stress responses. This work exemplifies how in-cell structural biology can expand the understanding of mechanisms of action for extensively studied antibiotics.
凍結剤: ETHANE-PROPANE / 装置: HOMEMADE PLUNGER 詳細: Back-side blotting for 2-3 seconds before plunging using a manual plunger without an environmental control chamber..
詳細
Mycoplasma pneumoniae M129 cells were grown on gold Quantifoil grids at 37 Celsius in modified Hayflick medium. Treatment with chloramphenicol at a final concentration of 0.2 mg/ml was performed for approximately 15 minutes before plunge freezing.
フィルム・検出器のモデル: GATAN K3 BIOQUANTUM (6k x 4k) 実像数: 1 / 平均電子線量: 3.34 e/Å2 詳細: Gatan K3 camera in non-CDS counting mode, targeted dose rate on camera ~20 e/pixel/second, 10 frames per tilt image, constant exposure time for each tilt, pixel size 1.329A