2jsx

From Proteopedia

Revision as of 15:44, 20 March 2008

Solution structure of the E. coli Tat proofreading chaperone protein NapD

Overview

The twin-arginine transport (Tat) system is dedicated to the translocation of folded proteins across the bacterial cytoplasmic membrane. Proteins are targeted to the Tat system by signal peptides containing a twin-arginine motif. In Escherichia coli, many Tat substrates bind redox-active cofactors in the cytoplasm before transport. Coordination of cofactor insertion with protein export involves a "Tat proofreading" process in which chaperones bind twin-arginine signal peptides, thus preventing premature export. The initial Tat signal-binding proteins described belonged to the TorD family, which are required for assembly of N- and S-oxide reductases. Here, we report that E. coli NapD is a Tat signal peptide-binding chaperone involved in biosynthesis of the Tat-dependent nitrate reductase NapA. NapD binds tightly and specifically to the NapA twin-arginine signal peptide and suppresses signal peptide translocation activity such that transport via the Tat pathway is retarded. High-resolution, heteronuclear, multidimensional NMR spectroscopy reveals the 3D solution structure of NapD. The chaperone adopts a ferredoxin-type fold, which is completely distinct from the TorD family. Thus, NapD represents a new family of twin-arginine signal-peptide-binding proteins.

About this Structure

2JSX is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Structural diversity in twin-arginine signal peptide-binding proteins., Maillard J, Spronk CA, Buchanan G, Lyall V, Richardson DJ, Palmer T, Vuister GW, Sargent F, Proc Natl Acad Sci U S A. 2007 Oct 2;104(40):15641-6. Epub 2007 Sep 27. PMID:17901208

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