A novel ancestral protein of Drosophila alcohol dehydrogenase in Streptomyces?

Polyclonal antibodies raised against purified Drosophila alcohol dehydrogenase (ADH) were used in Western blot analyses to search for structurally and/or immunologically related proteins in prokaryotes and eukaryotes. No immunological-reactive protein was detected in a flesh fly, a locust, and butterflies. Immunological similarity with the 50-kDa PQQ-glucose dehydrogenase (GluDH)-B enzyme of Acinetobacter calcoaceticus was found, but the cross-reactivity apparently is dependent on the high hydrophilic character of this protein. Antibodies against PQQ-GluDH did not recognize Drosophila ADH. In five of seven species of the gram-positive soil bacteria actinomycetes tested, a protein approximately 28-30 kDa in subunit size was strongly recognized by alpha-DADH. It is probably not one of the two proteins with known homology to Drosophila ADH, viz., the actIII gene product and 20 beta-hydroxysteroid dehydrogenase. The protein is present in both the soluble and the pellet-membrane fraction of the cells. The protein has a late temporal expression in surface-grown cultures and, therefore, might be involved in secondary metabolism.