Proton gradients in bacterial protein translocation

The bacterial translocon SecYEG transports bacterial proteins across the plasma membrane. As any directed movement, translocation requires energy. It may come from ATP (adenosine triphosphate) hydrolysis that enables the motor protein SecA to push proteins through SecYEG channels. Alternatively translocation may directly be driven by the transmembrane proton gradient. This appears to be more efficient than first using this proton gradient to produce ATP. The project aims at exploring how the proton gradient drives protein translocation. We will use state of the art techniques, which allow monitoring single translocation complexes both optically and electrically in a single experiment. Insight into the role of protons may be used to manipulate the protein translocation rate for biotechnological purposes or to be able to monitor folding of membrane proteins.

Proton gradients in bacterial protein translocation The bacterial translocon SecYEG transports bacterial proteins across the plasma membrane. As any directed movement, translocation requires energy. It may come from ATP (adenosine triphosphate) hydrolysis that enables the motor protein SecA to push proteins through SecYEG channels. Alternatively, translocation may be directly driven by the transmembrane proton gradient, the so-called proton-motive force, PMF. The project studied the regulation of SecYEG by the components of PMF, the transmembrane electrical potential, and the difference in pH across the cell membrane. We developed a state-of-the-art technique that allows monitoring the dynamics of a single translocation complex. This technique enabled us to identify regions in the translocon which sense the PMF. The obtained insight may be used to manipulate the protein translocation rate for biotechnological purposes.