title: Co-operation between different targeting pathways during integration of a membrane protein.
abstract: Membrane protein assembly is a fundamental process in all cells. The membrane-bound Rieske iron-sulfur protein is an essential component of the cytochrome bc(1) and cytochrome b(6)f complexes, and it is exported across the energy-coupling membranes of bacteria and plants in a folded conformation by the twin arginine protein transport pathway (Tat) transport pathway. Although the Rieske protein in most organisms is a monotopic membrane protein, in actinobacteria, it is a polytopic protein with three transmembrane domains. In this work, we show that the Rieske protein of Streptomyces coelicolor requires both the Sec and the Tat pathways for its assembly. Genetic and biochemical approaches revealed that the initial two transmembrane domains were integrated into the membrane in a Sec-dependent manner, whereas integration of the third transmembrane domain, and thus the correct orientation of the iron-sulfur domain, required the activity of the Tat translocase. This work reveals an unprecedented co-operation between the mechanistically distinct Sec and Tat systems in the assembly of a single integral membrane protein.
authors.affiliation: Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee, Scotland, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Keller
authors.forename: Jeanine
authors.initials: J
authors.lastname: de Keyzer
authors.forename: Arnold J M
authors.initials: AJ
authors.lastname: Driessen
authors.forename: Tracy
authors.initials: T
authors.lastname: Palmer
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D014450:Electron Transport Complex III / Q000737:chemistry* / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D016415:Sequence Alignment; D048372:Streptomyces coelicolor / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C037989:Rieske iron-sulfur protein; C412443:YIDC protein, E coli; C408585:twin-arginine translocase complex, E coli; D014450:Electron Transport Complex III