Large-Peptide Permeation Through a Membrane Channel: Understanding Protamine Translocation Through CymA from Klebsiella Oxytoca*.

ABSTRACT: Quantifying the passage of the large peptide protamine (Ptm) across CymA, a passive channel for cyclodextrin uptake, is in the focus of this study. Using a reporter-pair-based fluorescence membrane assay we detected the entry of Ptm into liposomes containing CymA. The kinetics of the Ptm entry was independent of its concentration suggesting that the permeation through CymA is the rate-limiting factor. Furthermore, we reconstituted single CymA channels into planar lipid bilayers and recorded the ion current fluctuations in the presence of Ptm. To this end, we were able to resolve the voltage-dependent entry of single Ptm peptide molecules into the channel. Extrapolation to zero voltage revealed about 1-2 events per second and long dwell times, in agreement with the liposome study. Applied-f

SUBMITTER: Pangeni S 

PROVIDER: S-EPMC8049027 | biostudies-literature | 2021 Apr

REPOSITORIES: biostudies-literature