The role of carotenoids in proton-pumping rhodopsin as a primitive solar energy conversion system

Kimleng Chuon, Jin-gon Shim, Se-Hwan Kim, Shin-Gyu Cho, Seanghun Meas, Kun-Wook Kang, Ji-Hyun Kim, Ishita Das, Mordechai Sheves, Kwang-Hwan Jung

Research output: Contribution to journalArticlepeer-review

Abstract

Rhodopsin and carotenoids are two molecules that certain bacteria use to absorb and utilize light. Type I rhodopsin, the simplest active proton transporter, converts light energy into an electrochemical potential. Light produces a proton gradient, which is known as the proton motive force across the cell membrane. Some carotenoids are involved in light absorbance and transfer of absorbed energy to chlorophyll during photosynthesis. A previous study in Salinibacter ruber has shown that carotenoids act as antennae to harvest light and transfer energy to retinal in xanthorhodopsin (XR). Here, we describe the role of canthaxanthin (CAN), a carotenoid, as an antenna for Gloeobacter rhodopsin (GR). The non-covalent complex formed by the interaction between CAN and GR doubled the proton pumping speed and improved the pumping capacity by 1.5-fold. The complex also tripled the proton pumping speed and improved the pumping capacity by 5-fold in the presence of strong and weak light, respectively. Interestingly, when canthaxanthin was bound to Gloeobacter rhodopsin, it showed a 126-fold increase in heat resistance, and it survived better under drought conditions than Gloeobacter rhodopsin. The results suggest direct complementation of Gloeobacter rhodopsin with a carotenoid for primitive solar energy harvesting in cyanobacteria.

Original languageEnglish
Article number112241
JournalJournal of photochemistry and photobiology. B, Biology
Volume221
DOIs
StatePublished - Aug 2021

All Science Journal Classification (ASJC) codes

  • Radiation
  • Radiological and Ultrasound Technology
  • Biophysics
  • Radiology Nuclear Medicine and imaging

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