Structural investigation of the transmembrane C domain of the mannitol permease from Escherichia coli using 5-FTrp fluorescence spectroscopy

► 17 single Trp mutants of the mannitol transporter were labeled with 5-fluorotryptophan. ► The structure of the two protomers in this dimeric transporter are different. ► B domain phosphorylation induces long-range conformational changes in the C domain. ► Many parts of the C domain are involved in sugar translocation.