Structural diversity in twin-arginine signal peptide-binding proteins

TY - JOUR

T1 - Structural diversity in twin-arginine signal peptide-binding proteins

AU - Maillard, Julien

AU - Spronk, Chris A. E. M.

AU - Buchanan, Grant

AU - Lyall, Verity

AU - Richardson, David J.

AU - Palmer, Tracy

AU - Vuister, Geerten W.

AU - Sargent, Frank

A2 - Clemons, William M.

N1 - dc.publisher: National Academy of Sciences

PY - 2007

Y1 - 2007

N2 - 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.

AB - 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.

KW - Metalloenzyme biosynthesis

KW - Molecular chaperone

KW - NMR solution structure

KW - Protein-protein interactions

KW - Twin-arginine transport pathway

U2 - 10.1073/pnas.0703967104

DO - 10.1073/pnas.0703967104

M3 - Article

C2 - 17901208

SN - 1091-6490

VL - 104

SP - 15641

EP - 15646

JO - Proceedings of the National Academy of Sciences

JF - Proceedings of the National Academy of Sciences

IS - 40

ER -