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The twin arginine protein transport (Tat) system transports folded proteins across the cytoplasmic membranes of prokaryotes and the thylakoid membranes of plant chloroplasts. In Escherichia coli, the TatB and TatC components form a multivalent receptor complex that binds Tat substrates. Here, we have used a genetic fusion approach to construct covalent TatC oligomers in order to probe the organisation of TatC. A fused dimer of TatC supported Tat transport activity and was fully stable in vivo. Inactivating point mutations in one or other of the TatC units in the fused TatC dimer did not inactivate TatC function, indicating that only one TatC protomer in the TatC fused dimer needs to be active. Larger covalent fusions of TatC also supported Tat transport activity but were degraded in vivo to release smaller TatC forms. Taken together, these results strongly suggest that TatC forms a functional dimer, and support the idea that there is an even number of TatC protomers in the TatBC complex.

Original publication

DOI

10.1159/000329076

Type

Journal article

Journal

J Mol Microbiol Biotechnol

Publication Date

2011

Volume

20

Pages

168 - 175

Keywords

Cell Membrane, Escherichia coli, Escherichia coli Proteins, Membrane Transport Proteins, Mutation, Peptidyl Transferases, Protein Binding, Protein Multimerization, Protein Transport, Recombinant Fusion Proteins