Dataset Information

GNPS - The Antarctic Chlamydomonas sp. UWO241 exhibits constitutively high cyclic electron flow

ABSTRACT: The Antarctic green alga Chlamydomonas sp. UWO241 (UWO241) survives in the deep photoc zone of the permanently ice-covered Lake Bonney in the McMurdo Dry Valleys. The extreme habitat in its natural environment has given way to unique adaptive mechanisms in this halotolerant psychrophile. One of the most striking phenotype of UWO241 is the constitutive upregulation of cyclic electron flow (CEF) around Photosystem I (PSI). This CEF is associated with the formation of a PSI-cytochrome b6f supercomplex that is stable under conditions of high salinity, corresponding to its natural habitat. Although studies have been done to understand the changes in the photosynthetic apparatus associated with increased CEF, not much is known about the purpose of constitutive CEF in UWO241. In this study, we examined the changes in the metabolism associated with increased in CEF and PSI-supercomplex formation in UWO241 under high salinity. Using Electrochomic Shift (ECS) based spectroscopy we identified a higher NPQ and proton motif flux through ATP synthase associated with UWO241 under high salinity. This higher proton flux was associated with high alternative electron transport when plotted against linear electron flow. We also identified several proteins associated with PSI-cytb6f supercomplex in UWO241 that have not been shown before. A Bestrophin-like protein was identified in the whole cell proteome of UWO241 suggesting high capacity for NPQ. Using comparative shotgun proteomics we identified a total of 98 proteins that were significantly affected under high CEF phenotype in UWO241. Out of the 98 proteins, 46 were upregulated and belonged to Calvin cycle, secondary metabolism and translational machinery. Several enzymes in the secondary metabolic Shikimate pathway were upregulated under high CEF phenotype, with one protein involved in downstream indole acetic acid (IAA) biosynthesis upregulated. Metabolomics revealed upregulation of compatible solutes and downregulation of tryptophan in UWO241 under high salinity. We suggest that UWO241 maintains constitutively high CEF with associated PSI-cytb6f supercomplex under native high salinity conditions to rewire its downstream metabolism towards higher carbon fixation capacity and that fixed carbon is utilized to make secondary metabolites necessary for adaptation in its extreme habitat.

INSTRUMENT(S): LTQ XL

ORGANISM(S): Chlamydomonas Sp. Uwo 241

SUBMITTER: XIN WANG

PROVIDER: MSV000084382 | GNPS |

SECONDARY ACCESSION(S): PXD015585

REPOSITORIES: GNPS

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<i>Chlamydomonas</i> sp. UWO 241 Exhibits High Cyclic Electron Flow and Rewired Metabolism under High Salinity.

Kalra Isha I Wang Xin X Cvetkovska Marina M Jeong Jooyeon J McHargue William W Zhang Ru R Hüner Norman N Yuan Joshua S JS Morgan-Kiss Rachael R

Plant physiology 20200330 2

The Antarctic green alga <i>Chlamydomonas</i> sp. UWO 241 (UWO 241) is adapted to permanent low temperatures, hypersalinity, and extreme shade. One of the most striking phenotypes of UWO 241 is an altered PSI organization and constitutive PSI cyclic electron flow (CEF). To date, little attention has been paid to CEF during long-term stress acclimation, and the consequences of sustained CEF in UWO 241 are not known. In this study, we combined photobiology, proteomics, and metabolomics to understa ...[more]

PMID: 32229607

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Project description:The Antarctic green alga Chlamydomonas sp. UWO241 (UWO241) survives in the deep photoc zone of the permanently ice-covered Lake Bonney in the McMurdo Dry Valleys. The extreme habitat in its natural environment has given way to unique adaptive mechanisms in this halotolerant psychrophile. One of the most striking phenotype of UWO241 is the constitutive upregulation of cyclic electron flow (CEF) around Photosystem I (PSI). This CEF is associated with the formation of a PSI-cytochrome b6f supercomplex that is stable under conditions of high salinity, corresponding to its natural habitat. Although studies have been done to understand the changes in the photosynthetic apparatus associated with increased CEF, not much is known about the purpose of constitutive CEF in UWO241. In this study, we examined the changes in the metabolism associated with increased in CEF and PSI-supercomplex formation in UWO241 under high salinity. Using Electrochomic Shift (ECS) based spectroscopy we identified a higher NPQ and proton motif flux through ATP synthase associated with UWO241 under high salinity. This higher proton flux was associated with high alternative electron transport when plotted against linear electron flow. We also identified several proteins associated with PSI-cytb6f supercomplex in UWO241 that have not been shown before. A Bestrophin-like protein was identified in the whole cell proteome of UWO241 suggesting high capacity for NPQ. Using comparative shotgun proteomics we identified a total of 98 proteins that were significantly affected under high CEF phenotype in UWO241. Out of the 98 proteins, 46 were upregulated and belonged to Calvin cycle, secondary metabolism and translational machinery. Several enzymes in the secondary metabolic Shikimate pathway were upregulated under high CEF phenotype, with one protein involved in downstream indole acetic acid (IAA) biosynthesis upregulated. Metabolomics revealed upregulation of compatible solutes and downregulation of tryptophan in UWO241 under high salinity. We suggest that UWO241 maintains constitutively high CEF with associated PSI-cytb6f supercomplex under native high salinity conditions to rewire its downstream metabolism towards higher carbon fixation capacity and that fixed carbon is utilized to make secondary metabolites necessary for adaptation in its extreme habitat.