PT - JOURNAL ARTICLE AU - Jonas Wietek AU - Silvia Rodriguez-Rozada AU - Janine Tutas AU - Federico Tenedini AU - Christiane Grimm AU - Thomas G. Oertner AU - Peter Soba AU - Peter Hegemann AU - J. Simon Wiegert TI - Artificial anion-conducting channelrhodopsins with tuned spectra, modified kinetics and enhanced light sensitivity AID - 10.1101/156422 DP - 2017 Jan 01 TA - bioRxiv PG - 156422 4099 - http://biorxiv.org/content/early/2017/06/27/156422.short 4100 - http://biorxiv.org/content/early/2017/06/27/156422.full AB - Genetic engineering of natural light-gated ion channels has proven a powerful way to generate optogenetic tools for a wide variety of applications. In recent years, blue light-activated artificial anion conducting channelrhodopsins (aACRs) have been developed, improved, and were successfully applied in vivo. We asked whether the approaches used to create aACRs can be transferred to other well-characterized cation-conducting channelrhodopsins (CCRs) to obtain aACRs with a broad spectrum of biophysical properties. We generated 22 variants using two conversion strategies applied to 11 CCRs and screened them for membrane expression, photocurrents and anion selectivity. We obtained two novel aACRs, Phobos and Aurora, with blue- and red-shifted action spectra and photocurrents similar to existing aACRs. Furthermore, step-function mutations greatly enhanced light sensitivity due to a slowed-down photocycle. These bistable aACRs can be reversibly toggled between open and closed states with brief light pulses of different wavelengths. All new aACRs reliably inhibited action potential firing in pyramidal CA1 neurons. Expressed in Drosophila larvae in vivo, aACRs conveyed robust and specific light-dependent inhibition of locomotion and nociception.