TY - JOUR
T1 - Overlapping transport and chaperone-binding functions within a bacterial twin-arginine signal peptide
AU - Grahl, Sabine
AU - Maillard, Julien
AU - Spronk, Chris A. E. M.
AU - Vuister, Geerten W.
AU - Sargent, Frank
PY - 2012/3
Y1 - 2012/3
N2 - The twin-arginine translocation (Tat) pathway is a protein targeting system present in many prokaryotes. The physiological role of the Tat pathway is the transmembrane translocation of fully-folded proteins, which are targeted by N-terminal signal peptides bearing conserved SRRxFLK twin-arginine amino acid motifs. In Escherichia coli the majority of Tat targeted proteins bind redox cofactors and it is important that only mature, cofactor-loaded precursors are presented for export. Cellular processes have been unearthed that sequence these events, for example the signal peptide of the periplasmic nitrate reductase (NapA) is bound by a cytoplasmic chaperone (NapD) that is thought to regulate assembly and export of the enzyme. In this work, genetic, biophysical and structural approaches were taken to dissect the interaction between NapD and the NapA signal peptide. A NapD binding epitope was identified towards the N-terminus of the signal peptide, which overlapped significantly with the twin-arginine targeting motif. NMR spectroscopy revealed that the signal peptide adopted a a-helical conformation when bound by NapD, and substitution of single residues within the NapA signal peptide was sufficient to disrupt the interaction. This work provides an increased level of understanding of signal peptide function on the bacterial Tat pathway.
AB - The twin-arginine translocation (Tat) pathway is a protein targeting system present in many prokaryotes. The physiological role of the Tat pathway is the transmembrane translocation of fully-folded proteins, which are targeted by N-terminal signal peptides bearing conserved SRRxFLK twin-arginine amino acid motifs. In Escherichia coli the majority of Tat targeted proteins bind redox cofactors and it is important that only mature, cofactor-loaded precursors are presented for export. Cellular processes have been unearthed that sequence these events, for example the signal peptide of the periplasmic nitrate reductase (NapA) is bound by a cytoplasmic chaperone (NapD) that is thought to regulate assembly and export of the enzyme. In this work, genetic, biophysical and structural approaches were taken to dissect the interaction between NapD and the NapA signal peptide. A NapD binding epitope was identified towards the N-terminus of the signal peptide, which overlapped significantly with the twin-arginine targeting motif. NMR spectroscopy revealed that the signal peptide adopted a a-helical conformation when bound by NapD, and substitution of single residues within the NapA signal peptide was sufficient to disrupt the interaction. This work provides an increased level of understanding of signal peptide function on the bacterial Tat pathway.
UR - http://www.scopus.com/inward/record.url?scp=84858296338&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2958.2012.08005.x
DO - 10.1111/j.1365-2958.2012.08005.x
M3 - Article
C2 - 22329966
SN - 0950-382X
VL - 83
SP - 1254
EP - 1267
JO - Molecular Microbiology
JF - Molecular Microbiology
IS - 6
ER -