Features of a twin-arginine signal peptide required for recognition by a Tat proofreading chaperone

Abstract

The twin-arginine translocation (Tat) system is a bacterial protein targeting pathway. Tat-targeted proteins display signal peptides containing a distinctive SRRxFLK ‘twin-arginine’ motif. The Escherichia coli trimethylamine N-oxide reductase (TorA) bears a bifunctional Tat signal peptide, which directs protein export and serves as a binding site for the TorD biosynthetic chaperone. Here, the physical interaction between TorD and the TorA signal peptide was investigated. A single substitution within the TorA signal peptide (L31Q) was sufficient to impair TorD binding. Screening of a random torD mutant library identified a variant TorD protein (Q7L) that displayed increased binding affinity for the TorA signal peptide. Structured summary MINT- 6796225, MINT- 6796279, MINT- 6796298, MINT- 6796315, MINT- 6796332, MINT- 6796350, MINT- 6796371, MINT- 6796391, MINT- 6796410, MINT- 6796429, MINT- 6796446, MINT- 6796460: TorD (uniprotkb: P36662) physically interacts (MI: 0218) with TorA (uniprotkb: P33225) by two-hybrid (MI: 0018) MINT- 6796515, MINT- 6796563, MINT- 6796589, MINT- 6796624, MINT- 6796648, MINT- 6796666, MINT- 6796770, MINT- 6796750: TorA (uniprotkb: P33225) binds (MI: 0407) to TorD (uniprotkb: P36662) by isothermal titration calorimetry (MI: 0065)