COMPARISON OF THE BACTERIAL HELA PROTEIN TO THE F508 REGION OF THE CYSTIC-FIBROSIS TRANSMEMBRANE REGULATOR

The HelA protein of Rhodobacter capsulatus is the ATP-binding-cassette subunit of an exporter complex required for cytochrome c biogenesis. By primary sequence comparisons the F88 residue of HelA is similar to the F508 residue of the cystic fibrosis transmembrane regulator (CFTR) protein. Previous studies have established that CFTR F508 Delta or F5 08R proteins are defective but F508C is functional. Our results demons trate that the HelA F88 mutants functionally mimic the phenotypes of k nown CFTR F508 mutants. The phenotypes of additional HelA mutants and the in vivo steady-state levels of these proteins are also reported.