Structural Dynamics of the Functional Nonameric Type III Translocase Export Gate.

Type III protein secretion is widespread in Gram-negative pathogens. It comprises the injectisome with a surface-exposed needle and an inner membrane translocase. The translocase contains the SctRSTU export channel enveloped by the export gate subunit SctV that binds chaperone/exported clients and forms a putative ante-chamber.

New approach for membrane protein reconstitution into peptidiscs and basis for their adaptability to different proteins.

Previously we introduced peptidiscs as an alternative to detergents to stabilize membrane proteins in solution (Carlson et al., 2018). Here, we present 'on-gradient' reconstitution, a new gentle approach for the reconstitution of labile membrane-protein complexes, and used it to reconstitute reaction center complexes, demonstrating that peptidiscs can adapt to transmembrane domains of very different sizes and shapes.

The Peptidisc, a simple method for stabilizing membrane proteins in detergent-free solution.

Membrane proteins are difficult to work with due to their insolubility in aqueous solution and quite often their poor stability in detergent micelles. Here, we present the peptidisc for their facile capture into water-soluble particles. Unlike the nanodisc, which requires scaffold proteins of different lengths and precise amounts of matching lipids, reconstitution of detergent solubilized proteins in peptidisc only requires a short amphipathic bi-helical peptide (NSP) and no extra lipids.