Peptide translocation across MOMP, the major outer membrane channel from Campylobacter jejuni

•Translocation of short poly-arginines across the MOMP channel has been determined.•Penta-arginine and Hepta-arginine translocate across the MOMP channel.•Voltage dependent kinetics to distinguish binding from translocation.

Here we report on translocation of short poly-arginines across the MOMP porin, the major outer membrane protein in the cell wall of Campylobacter jejuni. MOMP was purified to homogeneity from a pathogenic strain of C. jejuni. Its reconstitution in lipid membranes and measuring the ion-current revealed two main distinct populations of protein channels which we interpreted as mono and trimers. Addition of poly-arginines causes concentration and voltage dependent ion-current fluctuations. Increasing the transmembrane potential decreases the residence time of the peptide inside the channel indicating successful translocation. We conclude that poly-arginines can cross the outer membrane of Campylobacter through the MOMP channel.