Referenced in: none

Automatically associated channels: Kir2.3 , Slo1

Title: Channel properties of TpsB transporter FhaC point to two functional domains with a C-terminal protein-conducting pore.

Authors: Albano C Méli, Hélène Hodak, Bernard Clantin, Camille Locht, Gérard Molle, Françoise Jacob-Dubuisson, Nathalie Saint

Journal, date & volume: J. Biol. Chem., 2006 Jan 6 , 281, 158-66

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/16284399

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 beta-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.