The Chlamydomonas alternative oxidase 1 is regulated by cadmium stress: New insights into control of expression

Zalutskaya, Zhanneta; Ostroukhova, Mariya; Ermilova, Elena

doi:10.1016/j.envexpbot.2016.05.015

Cited by 13 publications

(7 citation statements)

References 64 publications

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“…CrAOX1 is within a genomic cluster involved in nitrate assimilation (48) and is contiguous to NRT2;3, which encodes a nitrite/nitrate transporter (47). Similar to other genes in this cluster, CrAOX1 is induced by nitrate and repressed by ammonium (52), but it also responds to various stress conditions (25,(52)(53)(54)(55). Until recently, CrAOX2 was thought to be constitutively or developmentally expressed, but at very low levels (52).…”

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confidence: 99%

The mitochondrial alternative oxidase from Chlamydomonas reinhardtii enables survival in high light

Kaye¹,

Huang²,

Clowez

et al. 2019

Journal of Biological Chemistry

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Edited by Ursula JakobPhotosynthetic organisms often experience extreme light conditions that can cause hyper-reduction of the chloroplast electron transport chain, resulting in oxidative damage. Accumulating evidence suggests that mitochondrial respiration and chloroplast photosynthesis are coupled when cells are absorbing high levels of excitation energy. This coupling helps protect the cells from hyper-reduction of photosynthetic electron carriers and diminishes the production of reactive oxygen species (ROS). To examine this cooperative protection, here we characterized Chlamydomonas reinhardtii mutants lacking the mitochondrial alternative terminal respiratory oxidases, CrAOX1 and CrAOX2. Using fluorescent fusion proteins, we experimentally demonstrated that both enzymes localize to mitochondria. We also observed that the mutant strains were more sensitive than WT cells to high light under mixotrophic and photoautotrophic conditions, with the aox1 strain being more sensitive than aox2. Additionally, the lack of CrAOX1 increased ROS accumulation, especially in very high light, and damaged the photosynthetic machinery, ultimately resulting in cell death. These findings indicate that the Chlamydomonas AOX proteins can participate in acclimation of C. reinhardtii cells to excess absorbed light energy. They suggest that when photosynthetic electron carriers are highly reduced, a chloroplast-mitochondria coupling allows safe dissipation of photosynthetically derived electrons via the reduction of O 2 through AOX (especially AOX1)-dependent mitochondrial respiration.

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confidence: 99%

The mitochondrial alternative oxidase from Chlamydomonas reinhardtii enables survival in high light

Kaye¹,

Huang²,

Clowez

et al. 2019

Journal of Biological Chemistry

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“…The total RNA was extracted, and cDNA strands were synthesized as described previously [9]. Real-time quantitative RT-PCR (RT-qPCR) reactions were performed on the Light Cycler Instrument (CFX96 Real-Time PCR Detection System, Bio-Rad) using SYBR Green I following a previously reported protocol [38]. The primer sequences are listed in Supplementary Table S2.…”

Section: Methodsmentioning

confidence: 99%

Truncated Hemoglobins 1 and 2 Are Implicated in the Modulation of Phosphorus Deficiency-Induced Nitric Oxide Levels in Chlamydomonas

Filina

Grinko

Ermilova

2019

Cells

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Truncated hemoglobins (trHbs) form a widely distributed family of proteins found in archaea, bacteria, and eukaryotes. Accumulating evidence suggests that trHbs may be implicated in functions other than oxygen delivery, but these roles are largely unknown. Characterization of the conditions that affect trHb expression and investigation of their regulatory mechanisms will provide a framework for elucidating the functions of these globins. Here, the transcription of Chlamydomonas trHb genes (THB1–12) under conditions of phosphorus (P) deprivation was analyzed. Three THB genes, THB1, THB2, and THB12 were expressed at the highest level. For the first time, we demonstrate the synthesis of nitric oxide (NO) under P-limiting conditions and the production of NO by cells via a nitrate reductase-independent pathway. To clarify the functions of THB1 and THB2, we generated and analyzed strains in which these THBs were strongly under-expressed by using an artificial microRNA approach. Similar to THB1 knockdown, the depletion of THB2 led to a decrease in cell size and chlorophyll levels. We provide evidence that the knockdown of THB1 or THB2 enhanced NO production under P deprivation. Overall, these results demonstrate that THB1 and THB2 are likely to contribute, at least in part, to acclimation responses in P-deprived Chlamydomonas.

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“…The primer pairs for RTqPCR are given in Additional file 1 : Table S1. RT qPCR was performed with a CFX96 Real-Time PCR Detection System (Bio Rad) using SYBR Green I according to [ 33 ]. Gene expression ratios were calculated with the ΔΔCt method [ 34 ].…”

Section: Methodsmentioning

confidence: 99%

“…The protein content was determined with amido black staining and protein gel blot analysis was performed as described [ 33 , 35 ]. After separation by SDS-PAGE on a 12% polyacrylamide gel ( w / v ), the proteins were transferred to nitrocellulose membranes (Carl Roth, Karlsruhe) with use of semidry blotting (Trans-blot SD BioRad).…”

Section: Methodsmentioning

confidence: 99%

Dual positive and negative control of Chlamydomonas PII signal transduction protein expression by nitrate/nitrite and NO via the components of nitric oxide cycle

Zalutskaya

Ermilova

2018

BMC Plant Biol

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BackgroundThe PII proteins constitute a large superfamily, present in all domains of life. Until now, PII proteins research in Chloroplastida (green algae and land plants) has mainly focused on post-translation regulation of these signal transductors. Emerging evidence suggests that PII level is tightly controlled with regard to the nitrogen source and the physiological state of cells.ResultHere we identify that a balance of positive (nitrate and nitrite) and negative (nitric oxide) signals regulates Chlamydomonas GLB1. We found that PII expression is downregulated by ammonium through a nitric oxide (NO)-dependent mechanism. We show that nitrate reductase (NR) and its partner, truncated hemoglobin 1 (THB1), participate in a signaling pathway for dual control of GLB1 expression. Moreover, NO dependent guanilate cyclase appeared to be involved in the negative control of GLB1 transcription.ConclusionThis study has revealed the existence of the complex GLB1 control at transcription level, which is dependent on nitrogen source. Importantly, we found that GLB1 gene expression pattern is very similar to that observed for nitrate assimilation genes, suggesting interconnecting/coordinating PII-dependent and nitrate assimilation pathways.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1540-x) contains supplementary material, which is available to authorized users.

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The Chlamydomonas alternative oxidase 1 is regulated by cadmium stress: New insights into control of expression

Cited by 13 publications

References 64 publications

The mitochondrial alternative oxidase from Chlamydomonas reinhardtii enables survival in high light

The mitochondrial alternative oxidase from Chlamydomonas reinhardtii enables survival in high light

Truncated Hemoglobins 1 and 2 Are Implicated in the Modulation of Phosphorus Deficiency-Induced Nitric Oxide Levels in Chlamydomonas

Dual positive and negative control of Chlamydomonas PII signal transduction protein expression by nitrate/nitrite and NO via the components of nitric oxide cycle

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