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