Protein translocation across cell membranes is a ubiquitous process required for protein secretion and membrane protein insertion. In bacteria, this is mostly mediated by the conserved SecYEG complex, driven through rounds of ATP hydrolysis by the cytoplasmic SecA, and the trans-membrane proton motive force. We have used single molecule techniques to explore SecY pore dynamics on multiple timescales in order to dissect the complex reaction pathway. The results show that SecA, both the signal sequence and mature components of the pre-protein, and ATP hydrolysis each have important and specific roles in channel unlocking, opening and priming for transport. After channel opening, translocation proceeds in two phases: a slow phase independent of substrate length, and a length-dependent transport phase with an intrinsic translocation rate of ~40 amino acids per second for the proOmpA substrate. Broad translocation rate distributions reflect the stochastic nature of polypeptide transport.
- Klíčová slova
- E. coli, SecA, SecYEG, fluorescence, kinetics, molecular biophysics, single molecule, stochastic, structural biology,
- MeSH
- adenosintrifosfát metabolismus MeSH
- adenosintrifosfatasy chemie genetika metabolismus MeSH
- bakteriální proteiny chemie genetika metabolismus MeSH
- buněčná membrána metabolismus MeSH
- Escherichia coli genetika metabolismus MeSH
- fluorescenční mikroskopie metody MeSH
- hydrolýza MeSH
- konformace proteinů MeSH
- molekulární modely MeSH
- mutace MeSH
- proteiny - lokalizační signály genetika MeSH
- proteiny SecA MeSH
- proteiny z Escherichia coli chemie genetika metabolismus MeSH
- protonmotorická síla * MeSH
- translokační kanály SEC chemie genetika metabolismus MeSH
- transport proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- adenosintrifosfát MeSH
- adenosintrifosfatasy MeSH
- bakteriální proteiny MeSH
- proteiny - lokalizační signály MeSH
- proteiny SecA MeSH
- proteiny z Escherichia coli MeSH
- translokační kanály SEC MeSH
