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The impact of chromophore choice on the assembly kinetics and primary photochemistry of a red/green cyanobacteriochrome


Buhrke, David (2021). The impact of chromophore choice on the assembly kinetics and primary photochemistry of a red/green cyanobacteriochrome. Physical Chemistry Chemical Physics (PCCP), 23(37):20867-20874.

Abstract

Cyanobacteriochromes (CBCRs) are bi-stable photoreceptor proteins with high potential for biotechnological applications. Most of these proteins utilize phycocyanobilin (PCB) as a light-sensing co-factor, which is unique to cyanobacteria, but some variants also incorporate biliverdin (BV). The latter are of particular interest for biotechnology due to the natural abundance and red-shifted absorption of BV. Here, AmI-g2 was investigated, a CBCR capable of binding both PCB and BV. The assembly kinetics and primary photochemistry of AmI-g2 with both chromophores were studied in vitro. The assembly reaction with PCB is roughly 10× faster than BV, and the formation of a non-covalent intermediate was identified as the rate-limiting step in the case of BV. This step is fast for PCB, where the formation of the covalent thioether bond between AmI-g2 and PCB becomes rate-limiting. The photochemical quantum yields of the forward and backward reactions of AmI-g2 were estimated and discussed in the context of homologous CBCRs.

Abstract

Cyanobacteriochromes (CBCRs) are bi-stable photoreceptor proteins with high potential for biotechnological applications. Most of these proteins utilize phycocyanobilin (PCB) as a light-sensing co-factor, which is unique to cyanobacteria, but some variants also incorporate biliverdin (BV). The latter are of particular interest for biotechnology due to the natural abundance and red-shifted absorption of BV. Here, AmI-g2 was investigated, a CBCR capable of binding both PCB and BV. The assembly kinetics and primary photochemistry of AmI-g2 with both chromophores were studied in vitro. The assembly reaction with PCB is roughly 10× faster than BV, and the formation of a non-covalent intermediate was identified as the rate-limiting step in the case of BV. This step is fast for PCB, where the formation of the covalent thioether bond between AmI-g2 and PCB becomes rate-limiting. The photochemical quantum yields of the forward and backward reactions of AmI-g2 were estimated and discussed in the context of homologous CBCRs.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Scopus Subject Areas:Physical Sciences > General Physics and Astronomy
Physical Sciences > Physical and Theoretical Chemistry
Uncontrolled Keywords:Physical and Theoretical Chemistry, General Physics and Astronomy
Language:English
Date:1 January 2021
Deposited On:10 Oct 2022 06:15
Last Modified:29 Jan 2024 02:45
Publisher:Royal Society of Chemistry
ISSN:1463-9076
OA Status:Hybrid
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.1039/d1cp02696h
PubMed ID:34374395
  • Content: Published Version
  • Language: English
  • Licence: Creative Commons: Attribution 4.0 International (CC BY 4.0)