Mechanism of absorption wavelength shifts in anion channelrhodopsin-1 mutants

Masaki Tsujimura, Tomoyasu Noji, Keisuke Saito, Keiichi Kojima, Yuki Sudo, Hiroshi Ishikita

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


Using a quantum mechanical/molecular mechanical approach, we show the mechanisms of how the protein environment of Guillardia theta anion channelrhodopsin-1 (GtACR1) can shift the absorption wavelength. The calculated absorption wavelengths for GtACR1 mutants, M105A, C133A, and C237A are in agreement with experimentally measured wavelengths. Among 192 mutant structures investigated, mutations at Thr101, Cys133, Pro208, and Cys237 are likely to increase the absorption wavelength. In particular, T101A GtACR1 was expressed in HEK293T cells. The measured absorption wavelength is 10 nm higher than that of wild type, consistent with the calculated wavelength. (i) Removal of a polar residue from the Schiff base moiety, (ii) addition of a polar or acidic residue to the β-ionone ring moiety, and (iii) addition of a bulky residue to increase the planarity of the β-ionone and Schiff base moieties are the basis of increasing the absorption wavelength.

Original languageEnglish
Article number148349
JournalBiochimica et Biophysica Acta - Bioenergetics
Issue number2
Publication statusPublished - Feb 1 2021


  • Chloride channel
  • Electrostatics
  • Optogenetics
  • Protein structure
  • Quantum chemistry
  • Rhodopsin

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology


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