1. Channel Properties of TpsB Transporter FhaC Point to Two Functional Domains with a C-terminal Protein-conducting Pore.
- Author
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Méli, Albano C., Hodak, Hélène, Clantin, Bernard, Locht, Camille, Molle, Gérard, Jacob-Dubuisson, Françoise, and Saint, Nathalie
- Subjects
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BIOLOGICAL transport , *GRAM-negative bacteria , *CHLOROPLASTS , *MITOCHONDRIA , *BORDETELLA pertussis , *GENETIC mutation - Abstract
Integral outer membrane transporters of the Omp85/TpsB superfamily mediate the translocation of proteins across, or their integration into, the outer membranes of Gram-negative bacteria, chloroplasts, and mitochondria. The Bordetella pertussis FhaC/FHA couple serves as a model for the two-partner secretion pathway in Gram-negative bacteria, with the TpsB protein, FhaC, being the specific transporter of its TpsA partner, FHA, across the outer membrane. In this work, we have investigated the structure/function relationship of FhaC by analyzing the ion channel properties of the wild type protein and a collection of mutants with varied FHA secretion activities. We demonstrated that the channel is formed by the C-terminal two-thirds of FhaC most likely folding into a β-barrel domain predicted to be conserved throughout the family. A C-proximal motif that represents the family signature appears essential for pore function. The N-terminal 200 residues of FhaC constitute a functionally distinct domain that modulates the pore properties and may participate in FHA recognition. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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