title: Enough is enough: TatA demand during Tat-dependent protein transport.
abstract: The twin-arginine translocation (Tat(1)) pathway is unique with respect to its property to translocate proteins in a fully folded conformation across ion-tight membranes. In chloroplasts and Gram-negative bacteria, Tat translocase consists of the integral subunits TatB and TatC, which are assumed to constitute the membrane receptor, and TatA, a bitopic membrane protein being responsible in a yet unknown manner for the membrane translocation step. Antibody inhibition of intrinsic thylakoidal TatA activity and recovery of transport by heterologously expressed, purified TatA allowed to exactly quantify the amount of TatA required to catalyse membrane transport of the model Tat substrate 16/23. We can show that TatA concentrations in the 100nM range are sufficient to efficiently catalyse membrane transport of the protein, which corresponds well to the amount of TatA identified in thylakoids. Furthermore, TatA shows cooperativity in its catalytic activity suggesting that Tat translocase operates as an allosteric enzyme complex.
authors: Institute of Biology - Plant Physiology, Martin Luther University Halle-Wittenberg, Weinbergweg 10, Germany.
authors: René Steffen
authors: RS
authors: Hauer
authors: René
authors: R
authors: Schlesier
authors: Kathleen
authors: K
authors: Heilmann
authors: Julia
authors: J
authors: Dittmar
authors: Mario
authors: M
authors: Jakob
authors: Ralf Bernd
authors: RB
authors: Klösgen
mesh_terms: D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001120:Arginine / Q000737:chemistry / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D021381:Protein Transport; D020524:Thylakoids / Q000737:chemistry / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D026901:Membrane Transport Proteins; C581720:TatA protein, Arabidopsis; D001120:Arginine