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Structure of TatA Paralog, TatE, Suggests a Structurally Homogeneous Form of Tat Protein Translocase That Transports Folded Proteins of Differing Diameter

Baglieri, Jacopo, Beck, Daniel, Vasisht, Nishi, Smith, Corinne J., Robinson, Colin (2012) Structure of TatA Paralog, TatE, Suggests a Structurally Homogeneous Form of Tat Protein Translocase That Transports Folded Proteins of Differing Diameter. Journal of Biological Chemistry, 287 (10). pp. 7335-7344. ISSN 0021-9258. (doi:10.1074/jbc.M111.326355) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided. (Contact us about this Publication)
Official URL
http://dx.doi.org/10.1074/jbc.M111.326355

Abstract

The twin-arginine translocation (Tat) system transports folded proteins across bacterial and plant thylakoid membranes. Most current models for the translocation mechanism propose the coalescence of a substrate-binding TatABC complex with a separate TatA complex. In Escherichia coli, TatA complexes are widely believed to form the translocation pore, and the size variation of TatA has been linked to the transport of differently sized substrates. Here, we show that the TatA paralog TatE can substitute for TatA and support translocation of Tat substrates including AmiA, AmiC, and TorA. However, TatE is found as much smaller, discrete complexes. Gel filtration and blue native electrophoresis suggest sizes between ?50 and 110 kDa, and single-particle processing of electron micrographs gives size estimates of 70–90 kDa. Three-dimensional models of the two principal TatE complexes show estimated diameters of 6–8 nm and potential clefts or channels of up to 2.5 nm diameter. The ability of TatE to support translocation of the 90-kDa TorA protein suggests alternative translocation models in which single TatA/E complexes do not contribute the bulk of the translocation channel. The homogeneity of both the TatABC and the TatE complexes further suggests that a discrete Tat translocase can translocate a variety of substrates, presumably through the use of a flexible channel. The presence and possible significance of double- or triple-ring TatE forms is discussed.

Item Type: Article
DOI/Identification number: 10.1074/jbc.M111.326355
Uncontrolled keywords: Membrane Transport Protein Export Protein Processing Protein Secretion Protein Translocation Tat Twin-arginine
Subjects: Q Science > QH Natural history > QH301 Biology
Q Science > QR Microbiology
Divisions: Faculties > Sciences > School of Biosciences
Depositing User: Colin Robinson
Date Deposited: 10 Jul 2013 10:26 UTC
Last Modified: 29 May 2019 10:22 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/34577 (The current URI for this page, for reference purposes)
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