title: TatA complexes exhibit a marked change in organisation in response to expression of the TatBC complex.
abstract: The twin-arginine translocation (Tat) system is an integral membrane protein complex that accomplishes the remarkable feat of transporting large, fully folded polypeptides across the inner membrane of bacteria, into the periplasm. InEscherichia coli, Tat comprises three membrane proteins: TatA, TatB and TatC. How these proteins arrange themselves in the inner membrane to permit passage of Tat substrates, whilst maintaining membrane integrity, is still poorly understood. TatA is the most abundant component of this complex and facilitates assembly of the transport mechanism. We have utilised immunogold labelling in combination with array tomography to gain insight into the localisation and distribution of the TatA protein inE. colicells. We show that TatA exhibits a uniform distribution throughout the inner membrane ofE. coliand that altering the expression of TatBC shows a previously uncharacterised distribution of TatA in the inner membrane. Array tomography was used to provide our first insight into this altered distribution of TatA in three-dimensional space, revealing that this protein forms linear clusters in the inner membrane ofE. coliupon increased expression of TatBC. This is the first indication that TatA organisation in the inner membrane alters in response to changes in Tat subunit stoichiometry.
authors.affiliation: School of Life Sciences, University of Warwick, Coventry CV4 7AL, U.K.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Smith
authors.affiliation: JEOL (UK) Ltd, Welwyn Garden City AL7 1LT, U.K.
authors.forename: Andrew
authors.initials: A
authors.lastname: Yarwood
authors.affiliation: Centre For Ultrastructural Imaging, King's College London, New Hunts House, Guy's Campus, London SE1 1UL, U.K.
authors.forename: Roland A
authors.initials: RA
authors.lastname: Fleck
authors.affiliation: School of Biosciences, University of Kent, Canterbury CT2 7NJ, U.K.
authors.forename: Colin
authors.initials: C
authors.lastname: Robinson
authors.affiliation: School of Life Sciences, University of Warwick, Coventry CV4 7AL, U.K. corinne.smith@warwick.ac.uk.
authors.forename: Corinne J
authors.initials: CJ
authors.lastname: Smith
mesh_terms: D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure*; D016253:Microscopy, Immunoelectron / Q000379:methods*; D046912:Multiprotein Complexes / Q000648:ultrastructure*; D009876:Operon; D011485:Protein Binding; D021381:Protein Transport
chemical_list: D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D046912:Multiprotein Complexes; C499697:TatA protein, E coli; C473116:TatB protein, E coli; C461379:TatC protein, E coli
keywords: electron microscopy; transmembrane proteins; transport