A functional water channel protein in the pathogenic bacterium Brucella abortus

The gene for a new bacterial aquaporin, AqpX, was cloned from the pathogeni c Gram-negative bacterium Brucella abortus. The gene was mapped on the larg e chromosome of B, abortus, It is flanked by one upstream and two downstrea m copies of the Brucella repeated sequence Bru-RS. Prediction from the nucl eotide sequence indicated that the protein is a member of the MIP family, w hich comprises channels for water and/or solute transport, Expression in Xe nopus oocytes and cryoelectron microscopy of Escherichia coli cells transfo rmed with the aqpX gene confirmed that the protein is an efficient water ch annel. Glycerol uptake experiments in E, coli also showed that the protein is not able to transport glycerol.