Targeting of thylakoid proteins by the ΔpH‐driven twin‐arginine translocation pathway requires a specific signal in the hydrophobic domain in conjunction with the twin‐arginine motif

FEBS Letters

Robinson, Colin¹  Hynds, Peter J.¹  Bogsch, Erik G.¹  Brink, Susanne¹  Edwards, Wayne R.¹ 

[1] Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK

关键词: Chloroplast;    Protein transport;    Targeting signal;    Thylakoid;    Sec-independent;   

DOI  :  10.1016/S0014-5793(98)01028-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Superficially similar cleavable targeting signals specify whether lumenal proteins are transported across the thylakoid membrane by a Sec- or ΔpH-dependent pathway. A twin-arginine motif is essential but not sufficient to direct ΔpH-dependent targeting; here we show that a second determinant is located in the hydrophobic region. A highly hydrophobic amino acid is found either two or three residues C-terminal to the twin-arginine in all known transfer peptides for the ΔpH-dependent system, and substitution of this residue in the 23-kDa (23K) peptide markedly inhibits translocation. Further, whereas the insertion of twin-arginine in a Sec-dependent precursor does not permit efficient ΔpH-dependent targeting, the simultaneous presence of a leucine at the +3 position (relative to the RR) enables the peptide to function as efficiently as an authentic transfer peptide. RRNVL, RRAAL and RRALA within a Sec targeting signal all support efficient ΔpH-dependent targeting, RRNVA is less effective and RRNAA/RRNAG are totally ineffective. We conclude that the core signal for this pathway is a twin-arginine together with an adjacent hydrophobic determinant.

【 授权许可】

Unknown