MOLECULAR CHARACTERIZATION OF AN ARABIDOPSIS-THALIANA CDNA-ENCODING ANOVEL PUTATIVE ADENYLATE TRANSLOCATOR OF HIGHER-PLANTS

We have isolated an Arabinopsis thaliana cDNA encoding a highly hydrop hobic membrane protein of 589 amino acids which contains 12 potential transmembrane helices and shows a high degree of similarity (43.5% ide ntity, 66.2% similarity) to the ATP/ADP translocase of the Gram-negati ve bacterium Rickettsia prowazekii, an obligate intracellular parasite responsible for the epidemic typhus. This rickettsial translocator re sides in the cytoplasmic membrane and allows the bacterium to exploit the host cytoplasmic ATP pool. We hypothesize that the A. thaliana hom olog of the R. prowazekii ATP/ADP translocase is the functional eukary otic equivalent and resides in the plastid inner envelope membrane whe re it functions as an ATP importer.