Assembling the Tat protein translocase

Felicity Alcock, Phillip J. Stansfeld (Lead / Corresponding author), Hajra Basit, Johann Habersetzer, Matthew A. B. Baker, Tracy Palmer, Mark I. Wallace, Ben C. Berks (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)
252 Downloads (Pure)

Abstract

The twin-arginine protein translocation system (Tat) transports folded proteins across the bacterial cytoplasmic membrane and the thylakoid membranes of plant chloroplasts. The Tat transporter is assembled from multiple copies of the membrane proteins TatA, TatB, and TatC. We combine sequence co-evolution analysis, molecular simulations, and experimentation to define the interactions between the Tat proteins of Escherichia coli at molecular-level resolution. In the TatBC receptor complex the transmembrane helix of each TatB molecule is sandwiched between two TatC molecules, with one of the inter-subunit interfaces incorporating a functionally important cluster of interacting polar residues. Unexpectedly, we find that TatA also associates with TatC at the polar cluster site. Our data provide a structural model for assembly of the active Tat translocase in which substrate binding triggers replacement of TatB by TatA at the polar cluster site. Our work demonstrates the power of co-evolution analysis to predict protein interfaces in multi-subunit complexes.

Original languageEnglish
Article numbere20718
Pages (from-to)1-28
Number of pages28
JournaleLife
Volume5
Early online date3 Dec 2016
DOIs
Publication statusPublished - 3 Dec 2016

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