Conflicts with diarrheal pathogens trigger rapid evolution of an intestinal signaling axis

Clayton M. Carey; Sarah E. Apple; Zoe A. Hilbert; Michael S. Kay; Nels C. Elde

Differences in toxin susceptibility were even more pronounced among GC-C encoded by bats. We cloned GC-C from representatives of the vesper bats: Myotis lucifugus (little brown bat), Eptesicus fuscus (big brown bat), and Miniopterus natalensis (Natal longfingered bat), as well as Old World fruit bats: Pteropus vampyrus (large flying fox) and Pteropus alecto (black flying fox) for expression in cell lines. This sampling captures roughly a 50 million year interval of divergence from the common ancestor of chiropteran bats 19 . We discovered a wide range of susceptibility to STa variants across bat species. While GC-C from the vesper bats E. fuscus and M. natalensis responded similarly to all four toxins at high concentrations and produced modest levels of cGMP comparable to human GC-C, cells expressing M. lucifugus, P. vampyrus, and P. alecto GC-C produced nearly 10-fold more cGMP in response to toxin treatments ( Figure 2D -F). Intriguingly, both P. vampyrus and P. alecto failed to respond to treatment with 10 µM Y-ST in notable contrast to GC-C encoded by M. lucifugus ( Figure 2D ). Additional comparisons across a wide range of toxin concentrations revealed that P. vampyrus GC-C is only activated by Y-ST stimulation at concentrations exceeding 10 µM, well outside probable concentrations encountered during infection 20 ( Figure 2E ). Thus, consistent with strong signatures of positive selection for GC-C from bats, susceptibility to STa variants widely differs between bat species, with some receptors appearing resistant to activation at physiologically plausible concentrations of toxin. The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.03.29.014761 doi: bioRxiv preprint