The entire N-terminal half of TatC is involved in twin-arginine precursor binding.
Translocation of twin-arginine precursor proteins across the cytoplasmic membrane of Escherichia coli requires the three membrane proteins TatA, TatB, and TatC. TatC and TatB were shown to be involved in precursor binding. We have analyzed in vitro a number of single alanine substitutions in tatC that were previously shown to compromise in vivo the function of the Tat translocase. All tatC mutants that were defective in precursor translocation into cytoplasmic membrane vesicles concomitantly interfered with precursor binding not only to TatC but also to TatB. Hence structural changes of TatC that affect precursor targeting simultaneously abolish engagement of the twin-arginine signal sequence with TatB and block the formation of a functional Tat translocase. Since these phenotypes were observed for tatC mutations spread over the first half of TatC, this entire part of the molecule must globally be involved in precursor binding.
Holzapfel
Eva
E
Institut für Biochemie und Molekularbiologie and Zentrum für Biochemie und Molekulare Zellforschung, Universität Freiburg, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany.
Eisner
Gottfried
G
Alami
Meriem
M
Barrett
Claire M L
CM
Buchanan
Grant
G
Lüke
Iris
I
Betton
Jean-Michel
JM
Robinson
Colin
C
Palmer
Tracy
T
Moser
Michael
M
Müller
Matthias
M
D001120:Arginine / Q000378:metabolism*; D001692:Biological Transport / Q000502:physiology; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D017434:Protein Structure, Tertiary
D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; C461379:TatC protein, E coli; D001120:Arginine