Dataset Information

Contrasting Effects of Acclimated Copper Limitation on the Photosynthetic Apparatus in Two Strains of the open ocean diatom Thalassiosira oceanica

ABSTRACT: The physiological adaptations of diatoms to cope with Cu limitation are largely unknown. In the present study we investigated the response to Cu limitation in two strains of the model open ocean diatom T. oceanica (CCMP 1003 and CCMP 1005), focusing on physiological and proteomic changes in the photosynthetic apparatus. Our results show remarkable differences between the adaptations of TO05 and TO03 to low Cu, highlighting significant intra specific variations.

INSTRUMENT(S): LTQ Orbitrap, Bruker Daltonics instrument model

ORGANISM(S): Thalassiosira Oceanica Thalassiosira Oceanica Ccmp1005

TISSUE(S): Cell Culture

SUBMITTER: Jenny Moon

LAB HEAD: Leonard James Foster

PROVIDER: PXD006237 | Pride | 2017-08-15

REPOSITORIES: Pride

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			Action	DRS
	JM_AH1005_InsolACu1_A12_01_847.d.zip	Other
	JM_AH1005_InsolACu1repeat_A12_01_890.d.zip	Other
	JM_AH1005_InsolACu2_A12_01_848.d.zip	Other
	JM_AH1005_InsolBCu1_B2_01_853.d.zip	Other
	JM_AH1005_InsolBCu1repeat_B2_01_952.d.zip	Other

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Project description:There is an intricate interaction between iron (Fe) and copper (Cu) physiology in diatoms. However, strategies to cope with low Cu are largely unknown. This study unveils the comprehensive restructuring of the photosynthetic apparatus in the diatom Thalassiosira oceanica (CCMP1003) in response to low Cu, at the physiological and proteomic level. The restructuring results in a shift from light harvesting for photochemistry-and ultimately for carbon fixation-to photoprotection, reducing carbon fixation and oxygen evolution. The observed decreases in the physiological parameters Fv/Fm, carbon fixation, and oxygen evolution, concomitant with increases in the antennae absorption cross section (σPSII), non-photochemical quenching (NPQ) and the conversion factor (φe:C/ηPSII) are in agreement with well documented cellular responses to low Fe. However, the underlying proteomic changes due to low Cu are very different from those elicited by low Fe. Low Cu induces a significant four-fold reduction in the Cu-containing photosynthetic electron carrier plastocyanin. The decrease in plastocyanin causes a bottleneck within the photosynthetic electron transport chain (ETC), ultimately leading to substantial stoichiometric changes. Namely, 2-fold reduction in both cytochrome b6f complex (cytb6f) and photosystem II (PSII), no change in the Fe-rich PSI and a 40- and 2-fold increase in proteins potentially involved in detoxification of reactive oxygen species (ferredoxin and ferredoxin:NADP+ reductase, respectively). Furthermore, we identify 48 light harvesting complex (LHC) proteins in the publicly available genome of T. oceanica and provide proteomic evidence for 33 of these. The change in the LHC composition within the antennae in response to low Cu underlines the shift from photochemistry to photoprotection in T. oceanica (CCMP1003). Interestingly, we also reveal very significant intra-specific strain differences. Another strain of T. oceanica (CCMP 1005) requires significantly higher Cu concentrations to sustain both its maximal and minimal growth rate compared to CCMP 1003. Under low Cu, CCMP 1005 decreases its growth rate, cell size, Chla and total protein per cell. We argue that the reduction in protein per cell is the main strategy to decrease its cellular Cu requirement, as none of the other parameters tested are affected. Differences between the two strains, as well as differences between the well documented responses to low Fe and those presented here in response to low Cu are discussed.

Dataset Information

Contrasting Effects of Acclimated Copper Limitation on the Photosynthetic Apparatus in Two Strains of the open ocean diatom Thalassiosira oceanica

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