Two Cyanobacterial Photoreceptors Regulate Photosynthetic Light Harvesting by Sensing Teal, Green, Yellow, and Red Light

ABSTRACT The genomes of many photosynthetic and nonphotosynthetic bacteria encode numerous phytochrome superfamily photoreceptors whose functions and interactions are largely unknown. Cyanobacterial genomes encode particularly large numbers of phytochrome superfamily members called cyanobacteriochro...

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Autores principales:	Lisa B. Wiltbank, David M. Kehoe
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2016
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/825d657be9b34145816d7808bab67583
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spelling	oai:doaj.org-article:825d657be9b34145816d7808bab675832021-11-15T15:49:40ZTwo Cyanobacterial Photoreceptors Regulate Photosynthetic Light Harvesting by Sensing Teal, Green, Yellow, and Red Light10.1128/mBio.02130-152150-7511https://doaj.org/article/825d657be9b34145816d7808bab675832016-03-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.02130-15https://doaj.org/toc/2150-7511ABSTRACT The genomes of many photosynthetic and nonphotosynthetic bacteria encode numerous phytochrome superfamily photoreceptors whose functions and interactions are largely unknown. Cyanobacterial genomes encode particularly large numbers of phytochrome superfamily members called cyanobacteriochromes. These have diverse light color-sensing abilities, and their functions and interactions are just beginning to be understood. One of the best characterized of these functions is the regulation of photosynthetic light-harvesting antenna composition in the cyanobacterium Fremyella diplosiphon by the cyanobacteriochrome RcaE in response to red and green light, a process known as chromatic acclimation. We have identified a new cyanobacteriochrome named DpxA that maximally senses teal (absorption maximum, 494 nm) and yellow (absorption maximum, 568 nm) light and represses the accumulation of a key light-harvesting protein called phycoerythrin, which is also regulated by RcaE during chromatic acclimation. Like RcaE, DpxA is a two-component system kinase, although these two photoreceptors can influence phycoerythrin expression through different signaling pathways. The peak responsiveness of DpxA to teal and yellow light provides highly refined color discrimination in the green spectral region, which provides important wavelengths for photosynthetic light harvesting in cyanobacteria. These results redefine chromatic acclimation in cyanobacteria and demonstrate that cyanobacteriochromes can coordinately impart sophisticated light color sensing across the visible spectrum to regulate important photosynthetic acclimation processes. IMPORTANCE The large number of cyanobacteriochrome photoreceptors encoded by cyanobacterial genomes suggests that these organisms are capable of extremely complex light color sensing and responsiveness, yet little is known about their functions and interactions. Our work uncovers previously undescribed cooperation between two photoreceptors with very different light color-sensing capabilities that coregulate an important photosynthetic light-harvesting protein in response to teal, green, yellow, and red light. Other cyanobacteriochromes that have been shown to interact functionally sense wavelengths of light that are close to each other, which makes it difficult to clearly identify their physiological roles in the cell. Our finding of two photoreceptors with broad light color-sensing capabilities and clearly defined physiological roles provides new insights into complex light color sensing and its regulation.Lisa B. WiltbankDavid M. KehoeAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 7, Iss 1 (2016)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Lisa B. Wiltbank David M. Kehoe Two Cyanobacterial Photoreceptors Regulate Photosynthetic Light Harvesting by Sensing Teal, Green, Yellow, and Red Light
description	ABSTRACT The genomes of many photosynthetic and nonphotosynthetic bacteria encode numerous phytochrome superfamily photoreceptors whose functions and interactions are largely unknown. Cyanobacterial genomes encode particularly large numbers of phytochrome superfamily members called cyanobacteriochromes. These have diverse light color-sensing abilities, and their functions and interactions are just beginning to be understood. One of the best characterized of these functions is the regulation of photosynthetic light-harvesting antenna composition in the cyanobacterium Fremyella diplosiphon by the cyanobacteriochrome RcaE in response to red and green light, a process known as chromatic acclimation. We have identified a new cyanobacteriochrome named DpxA that maximally senses teal (absorption maximum, 494 nm) and yellow (absorption maximum, 568 nm) light and represses the accumulation of a key light-harvesting protein called phycoerythrin, which is also regulated by RcaE during chromatic acclimation. Like RcaE, DpxA is a two-component system kinase, although these two photoreceptors can influence phycoerythrin expression through different signaling pathways. The peak responsiveness of DpxA to teal and yellow light provides highly refined color discrimination in the green spectral region, which provides important wavelengths for photosynthetic light harvesting in cyanobacteria. These results redefine chromatic acclimation in cyanobacteria and demonstrate that cyanobacteriochromes can coordinately impart sophisticated light color sensing across the visible spectrum to regulate important photosynthetic acclimation processes. IMPORTANCE The large number of cyanobacteriochrome photoreceptors encoded by cyanobacterial genomes suggests that these organisms are capable of extremely complex light color sensing and responsiveness, yet little is known about their functions and interactions. Our work uncovers previously undescribed cooperation between two photoreceptors with very different light color-sensing capabilities that coregulate an important photosynthetic light-harvesting protein in response to teal, green, yellow, and red light. Other cyanobacteriochromes that have been shown to interact functionally sense wavelengths of light that are close to each other, which makes it difficult to clearly identify their physiological roles in the cell. Our finding of two photoreceptors with broad light color-sensing capabilities and clearly defined physiological roles provides new insights into complex light color sensing and its regulation.
format	article
author	Lisa B. Wiltbank David M. Kehoe
author_facet	Lisa B. Wiltbank David M. Kehoe
author_sort	Lisa B. Wiltbank
title	Two Cyanobacterial Photoreceptors Regulate Photosynthetic Light Harvesting by Sensing Teal, Green, Yellow, and Red Light
title_short	Two Cyanobacterial Photoreceptors Regulate Photosynthetic Light Harvesting by Sensing Teal, Green, Yellow, and Red Light
title_full	Two Cyanobacterial Photoreceptors Regulate Photosynthetic Light Harvesting by Sensing Teal, Green, Yellow, and Red Light
title_fullStr	Two Cyanobacterial Photoreceptors Regulate Photosynthetic Light Harvesting by Sensing Teal, Green, Yellow, and Red Light
title_full_unstemmed	Two Cyanobacterial Photoreceptors Regulate Photosynthetic Light Harvesting by Sensing Teal, Green, Yellow, and Red Light
title_sort	two cyanobacterial photoreceptors regulate photosynthetic light harvesting by sensing teal, green, yellow, and red light
publisher	American Society for Microbiology
publishDate	2016
url	https://doaj.org/article/825d657be9b34145816d7808bab67583
work_keys_str_mv	AT lisabwiltbank twocyanobacterialphotoreceptorsregulatephotosyntheticlightharvestingbysensingtealgreenyellowandredlight AT davidmkehoe twocyanobacterialphotoreceptorsregulatephotosyntheticlightharvestingbysensingtealgreenyellowandredlight
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Two Cyanobacterial Photoreceptors Regulate Photosynthetic Light Harvesting by Sensing Teal, Green, Yellow, and Red Light

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