@article{DuanNagelGao2019,
  author    = {Duan, Xiaodong and Nagel, Georg and Gao, Shiqiang},
  title     = {Mutated channelrhodopsins with increased sodium and calcium permeability},
  series = {Applied Sciences},
  volume    = {9},
  journal   = {Applied Sciences},
  number    = {4},
  issn      = {2076-3417},
  doi       = {10.3390/app9040664},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-197435},
  pages     = {664},
  year      = {2019},
  abstract  = {(1) Background: After the discovery and application of Chlamydomonas reinhardtii channelrhodopsins, the optogenetic toolbox has been greatly expanded with engineered and newly discovered natural channelrhodopsins. However, channelrhodopsins of higher Ca\(^{2+}\) conductance or more specific ion permeability are in demand. (2) Methods: In this study, we mutated the conserved aspartate of the transmembrane helix 4 (TM4) within Chronos and PsChR and compared them with published ChR2 aspartate mutants. (3) Results: We found that the ChR2 D156H mutant (XXM) showed enhanced Na\(^+\) and Ca\(^{2+}\) conductance, which was not noticed before, while the D156C mutation (XXL) influenced the Na\(^+\) and Ca\(^{2+}\) conductance only slightly. The aspartate to histidine and cysteine mutations of Chronos and PsChR also influenced their photocurrent, ion permeability, kinetics, and light sensitivity. Most interestingly, PsChR D139H showed a much-improved photocurrent, compared to wild type, and even higher Na+ selectivity to H\(^+\) than XXM. PsChR D139H also showed a strongly enhanced Ca\(^{2+}\) conductance, more than two-fold that of the CatCh. (4) Conclusions: We found that mutating the aspartate of the TM4 influences the ion selectivity of channelrhodopsins. With the large photocurrent and enhanced Na\(^+\) selectivity and Ca\(^{2+}\) conductance, XXM and PsChR D139H are promising powerful optogenetic tools, especially for Ca\(^{2+}\) manipulation.},
  language  = {en}
}