A novel six-rhodopsin system in a single archaeon

Hsu Yuan Fu, Yu Cheng Lin, Yung Ning Chang, Hsiaochu Tseng, Ching Che Huang, Kang Cheng Liu, Ching Shin Huang, Che Wei Su, Rueyhung Roc Weng, Yin Yu Lee, Wailap Victor Ng, Chii Shen Yang

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

Microbial rhodopsins, a diverse group of photoactive proteins found in Archaea, Bacteria, and Eukarya, function in photosensing and photoenergy harvesting and may have been present in the resource-limited early global environment. Four different physiological functions have been identified and characterized for nearly 5,000 retinal-binding photoreceptors, these being ion transporters that transport proton or chloride and sensory rhodopsins that mediate light-attractant and/or -repellent responses. The greatest number of rhodopsins previously observed in a single archaeon had been four. Here, we report a newly discovered sixrhodopsin system in a single archaeon, Haloarcula marismortui, which shows a more diverse absorbance spectral distribution than any previously known rhodopsin system, and, for the first time, two light-driven proton transporters that respond to the same wavelength. All six rhodopsins, the greatest number ever identified in a single archaeon, were first shown to be expressed in H. marismortui, and these were then overexpressed in Escherichia coli. The proteins were purified for absorption spectra and photocycle determination, followed by measurement of ion transportation and phototaxis. The results clearly indicate the existence of a proton transporter system with two isochromatic rhodopsins and a new type of sensory rhodopsin-like transducer in H. marismortui.

Original languageEnglish (US)
Pages (from-to)5866-5873
Number of pages8
JournalJournal of bacteriology
Volume192
Issue number22
DOIs
StatePublished - Nov 2010

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