title: Photoconversion and Fluorescence Properties of a Red/Green-Type Cyanobacteriochrome AM1_C0023g2 That Binds Not Only Phycocyanobilin But Also Biliverdin.
abstract: Cyanobacteriochromes (CBCRs) are distantly related to the red/far-red responsive phytochromes. Red/green-type CBCRs are widely distributed among various cyanobacteria. The red/green-type CBCRs covalently bind phycocyanobilin (PCB) and show red/green reversible photoconversion. Recent studies revealed that some red/green-type CBCRs from chlorophyll d-bearing cyanobacterium Acaryochloris marina covalently bind not only PCB but also biliverdin (BV). The BV-binding CBCRs show far-red/orange reversible photoconversion. Here, we identified another CBCR (AM1_C0023g2) from A. marina that also covalently binds not only PCB but also BV with high binding efficiencies, although BV chromophore is unstable in the presence of urea. Replacement of Ser334 with Gly resulted in significant improvement in the yield of the BV-binding holoprotein, thereby ensuring that the mutant protein is a fine platform for future development of optogenetic switches. We also succeeded in detecting near-infrared fluorescence from mammalian cells harboring PCB-binding AM1_C0023g2 whose fluorescence quantum yield is 3.0%. Here the PCB-binding holoprotein is shown as a platform for future development of fluorescent probes.
authors.affiliation: Department of Biological Science, Faculty of Science, Shizuoka University Shizuoka, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Fushimi
authors.affiliation: Graduate School of Arts and Sciences, University of Tokyo Tokyo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nakajima
authors.affiliation: Graduate School of Arts and Sciences, University of Tokyo Tokyo, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Aono
authors.affiliation: Department of Biological Science, Faculty of Science, Shizuoka University Shizuoka, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Graduate School of Arts and Sciences, University of Tokyo Tokyo, Japan.
authors.lastname: Ni-Ni-Win
authors.affiliation: Graduate School of Arts and Sciences, University of TokyoTokyo, Japan; Core Research for Evolutional Science and Technology, Japan Science and Technology AgencySaitama, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ikeuchi
authors.affiliation: Graduate School of Arts and Sciences, University of Tokyo Tokyo, Japan.
authors.forename: Moritoshi
authors.initials: M
authors.lastname: Sato
authors.affiliation: Department of Biological Science, Faculty of Science, Shizuoka University Shizuoka, Japan.
authors.forename: Rei
authors.initials: R
authors.lastname: Narikawa
keywords: GFP; linear tetrapyrrole; live cell imaging; near-infrared fluorescence; optogenetics