Protein unfolding and translocation through pores occurs during trafficking between organelles, protein degradation and bacterial toxin delivery. In vivo, co-translocational unfolding can be affected by the end of the polypeptide that is threaded into the pore first. Recently, we have shown that co-translocational unfolding can be followed in a model system at the single-molecule level, thereby unravelling molecular steps and their kinetics. Here, we show that the unfolding kinetics of the model substrate thioredoxin, when pulled through an α-haemolysin pore, differ markedly depending on whether the process is initiated from the C terminus or the N terminus. Further, when thioredoxin is pulled from the N terminus, the unfolding pathway bifurcates: some molecules finish unfolding quickly, while others finish ~100 times slower. Our findings have important implications for the understanding of biological unfolding mechanisms and in the application of nanopore technology for the detection of proteins and their modifications.
Pubmed ID: 25197784 RIS Download
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Software suite for electrophysiology data acquisition and analysis by Molecular Devices. Used for the control and recording of voltage clamp, current clamp, and patch clamp experiments. The software suite consists of Clampex 11 Software for data acquisition, AxoScope 11 Software for background recording, Clampfit 11 Software for data analysis, and optional Clampfit Advanced Analysis Module for sophisticated and streamlined analysis.
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