1. Photocobilins integrate B12 and bilin photochemistry for enzyme control.
- Author
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Zhang, Shaowei, Jeffreys, Laura N., Poddar, Harshwardhan, Yu, Yuqi, Liu, Chuanyang, Patel, Kaylee, Johannissen, Linus O., Zhu, Lingyun, Cliff, Matthew J., Yan, Cunyu, Schirò, Giorgio, Weik, Martin, Sakuma, Michiyo, Levy, Colin W., Leys, David, Heyes, Derren J., and Scrutton, Nigel S.
- Subjects
QUATERNARY structure ,MICROBIAL genomes ,VISIBLE spectra ,PHOTOBIOLOGY ,ENZYMES ,PHOTOCHEMISTRY - Abstract
Photoreceptor proteins utilise chromophores to sense light and trigger a biological response. The discovery that adenosylcobalamin (or coenzyme B
12 ) can act as a light-sensing chromophore heralded a new field of B12 -photobiology. Although microbial genome analysis indicates that photoactive B12 -binding domains form part of more complex protein architectures, regulating a range of molecular–cellular functions in response to light, experimental evidence is lacking. Here we identify and characterise a sub-family of multi-centre photoreceptors, termed photocobilins, that use B12 and biliverdin (BV) to sense light across the visible spectrum. Crystal structures reveal close juxtaposition of the B12 and BV chromophores, an arrangement that facilitates optical coupling. Light-triggered conversion of the B12 affects quaternary structure, in turn leading to light-activation of associated enzyme domains. The apparent widespread nature of photocobilins implies involvement in light regulation of a wider array of biochemical processes, and thus expands the scope for B12 photobiology. Their characterisation provides inspiration for the design of broad-spectrum optogenetic tools and next generation bio-photocatalysts. Photoreceptor proteins utilise biological chromophores to regulate a large range of cellular processes in response to light. Here the authors identify and characterise a sub-family of multi-centre photoreceptors, termed photocobilins, that not only utilise B12 but also contain biliverdin (BV) as an additional chromophore. [ABSTRACT FROM AUTHOR]- Published
- 2024
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