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Bacterial proteins carrying twin‐R signal peptides are specifically targeted by the ΔpH‐dependent transport machinery of the thylakoid membrane system
Author(s) -
Halbig Dirk,
Hou Bo,
Freudl Roland,
Sprenger Georg A.,
Klösgen Ralf Bernd
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)00269-0
Subject(s) - twin arginine translocation pathway , thylakoid , biochemistry , signal peptide , periplasmic space , transport protein , membrane transport , chemistry , biophysics , translocase , chloroplast , biology , membrane , peptide sequence , escherichia coli , chromosomal translocation , gene
Glucose‐fructose oxidoreductase (GFOR), a periplasmic protein of Zymomonas mobilis , is synthesized as a precursor polypeptide with a twin‐R signal peptide for Sec‐independent protein export in bacteria. In higher plant chloroplasts, twin‐R signal peptides are specific targeting signals for the Sec‐independent ΔpH pathway of the thylakoid membrane system. In agreement with the assumed common phylogenetic origin of the two protein transport mechanisms, GFOR can be efficiently translocated by the ΔpH‐dependent pathway when analyzed with isolated thylakoid membranes. Transport is sensitive to the ionophore nigericin and competes with specific substrates for the ΔpH‐dependent transport route. In contrast, neither sodium azide nor enzymatic destruction of the nucleoside triphosphates in the assays affects thylakoid transport of GFOR indicating that the Sec apparatus is not involved in this process. Mutagenesis of the twin‐R motif in the GFOR signal peptide prevents membrane translocation of the protein emphasizing the importance of these residues for the transport process.