The ABCs of the amphipod P-glycoprotein: Heterologous production of the Abcb1 protein of a model species Eulimnogammarus verrucosus (Amphipoda: Gammaridae) from Lake Baikal

The multixenobiotic resistance (MXR) mechanism has been demonstrated to be present in a wide range of species, including aquatic organisms. However, amphipods (Crustacea: Malacostraca: Amphipoda), which constitute a large order of arthropods, are extremely poorly studied in this regard. Information on MXR proteins in these animals would be highly relevant, as some amphipods are important models in ecotoxicology due to their roles in many freshwater environments, including the ancient Lake Baikal. In this work, we studied the diversity of ABC transporters in the available transcriptomes of over 60 endemic Baikal amphipods in comparison to other related species. This showed that most classes of ABC transporters are present in all analyzed species and that most Baikal amphipods detectably express no more than one complete ABCB full transporter. We also showed that these sequences were conservative across different species, and their phylogeny was congruent with the species phylogeny. Thus, we chose the abcb1 coding sequence from Eulimnogammarus verrucosus, a widespread species playing an important role in the lake ecosystem, to establish the first heterologous expression system for an amphipod Abcb1/P-glycoprotein based on the Drosophila melanogaster S2 cell line. The resulting stably transfected S2 cell line was expressing the abcb1 of E. verrucosus about 1000 times higher than the homologous fly genes, and the target protein, Abcb1, showed to confer a high MXR-related efflux activity. Our results indicate the suitability of the S2-based expression systems for the study of arthropod ABCB1 homologs.