Insights on the S-layer Deinoxanthin Binding Complex of Deinococcus radiodurans, a massive protein complex with a porin-like structure and function

ABSTRACT: In Deinococcus radiodurans the outermost Surface layer is tightly matched with the rest of the cell wall into a compact and integrated structure able to contrast environmental adversities. The fundamental unit of this S-layer is the S-layer Deinoxanthin Binding Complex, which has been reported to bind the carotenoid deinoxanthin, to provide thermostability, and ultraviolet radiation resistance. Here we report the low-resolution structural features of this S-layer complex, which has been isolated retaining minor subunits not reported previously. In the present study the S-layer Deinoxanthin Binding Complex is shown to possess peculiar transport functions, as assessed by electrophysiological assays, and a porin-like structural organization, as observed by single particles analysis. In assays on lipid bilayer membranes, the increase in ion current related to the complex insertion, ranged between 10 and 100 pA, suggesting a very broad distribution of the pore sizes. The analysis of the ion current after a few insertions suggested minimal substates of ~0.3-3 nS and likely reflected the unitary conductance. Further assays, based on the reversal potential under different conditions revealed a rather non-selective channel. Eventually, the functional properties of this system and its porin-like organization provide essential elements for understanding the rationale of permeability in bacterial strains carrying S-layers.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Deinococcus Radiodurans Bacteria

SUBMITTER: Joanna Kirkpatrick  

LAB HEAD: Dr Dario Piano

PROVIDER: PXD015568 | Pride | 2020-02-18

REPOSITORIES: Pride