Topological studies on the twin-arginine translocase component TatC

authored by

Jana Behrendt, Kerstin Standar, Ute Lindenstrauß, Thomas Brüser

Abstract

The twin-arginine translocation (Tat) system can translocate folded proteins across biological membranes. Among the known Tat-system components in Escherichia coli, TatC is the only protein with multiple trans-membrane domains. TatC is important for translocon interactions with Tat substrates. The knowledge of its membrane topology is therefore crucial for the understanding of substrate binding and translocon function. Recently, based on active PhoA reporter fusions to the second predicted cytoplasmic loop of TatC, a topology with four trans-membrane domains has been suggested, calling in silico predictions of six trans-membrane domains into question. Here we report studies with translational fusions of TatC to the topological marker enzymes PhoA and LacZ which provide strong evidence for a six-trans-membrane domain topology. The stop transfer capacity of the fourth trans-membrane domain was found to be strongly influenced by the succeeding cytoplasmic domain. The presence of linker sequences at PhoA-fusion sites of the cytoplasmic domain induced PhoA leakage. In the case of one tested fusion (S185-PhoA), the stop-transfer efficiency was already low due to the negative charge in the center of the fourth trans-membrane domain (E170). The results point to the importance of cytoplasmic loops for the stabilization of stop-transfer sequences and revoke evidence for only four trans-membrane domains of TatC.

Organisation(s)

Institute of Microbiology

External Organisation(s)

Martin Luther University Halle-Wittenberg

Type

Article

Journal

FEMS Microbiology Letters

Volume

234

Pages

303-308

No. of pages

6

ISSN

0378-1097

Publication date

15.05.2004

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Microbiology, Molecular Biology, Genetics

Electronic version(s)

https://doi.org/10.1016/j.femsle.2004.03.048 (Access: Open)