Differential Proteome Analysis of <i>Chlamydomonas reinhardtii</i> Response to Arsenic Exposure

Abstract

The fresh water unicellular green alga Chlamydomonas reinhardtii was used to explore whether it could function as a model system to identify proteins that are differentially expressed in response to arsenate exposure. Cells were treated with different concentrations of arsenate ranging from 100 -400 M. When exposed to 200 M arsenate, the amount of live cells started to lessen on the second day and continued to diminish, indicating a toxic effect of arsenate. Proteomic analysis was used to investigate if these cells showed a specific response to arsenic-induced stress. Fifteen proteins were found that were over-expressed in the 200 M arsenate-treated samples and two proteins were found to be very strongly over-expressed in samples treated with 400 µM. These were selected for identification using liquid chromatography coupled with tandem mass spectrometry. Oxidative stress and protein damage were the major effects as shown by the up-regulation of Mn-superoxide dismutase, an oxygen-evolving enhancer protein, a chaperonin-like protein and a heat shock protein.

Responses of Chlamydomonas reinhardtii during the transition from P‐deficient to P‐sufficient growth (the P‐overplus response): The roles of the vacuolar transport chaperones and polyphosphate synthesis

“…In algae, the function of the proteasome is less characterized, but the UPS activity increases during cold, excess light, nutrients, and heavy metals stress (Pootakham et al. 2010, Walliwalagedara 2012, Valledor et al. 2013, Vallentine et al.…”

“…In higher plants, the UPS controls PO 4 3− starvation response, P homeostasis (Rojas-Triana et al 2013) and the import of proteins in the chloroplast (Jarvis and Lopez-Juez 2013). In algae, the function of the proteasome is less characterized, but the UPS activity increases during cold, excess light, nutrients, and heavy metals stress (Pootakham et al 2010, Walliwalagedara 2012, Valledor et al 2013, Vallentine et al 2014, Mendoza et al 2020). In our study, cells experiencing P repletion were not under stress (Table S3) so it is unlikely that the up-regulation of genes encoding proteins of the proteasome was due to any specific stressors.…”

The ubiquitin-proteasome pathway protects Chlamydomonas reinhardtii against selenite toxicity, but is impaired as reactive oxygen species accumulate

“…Methyl viologen treatment generates superoxide accompanied with the accumulation of ubiquitinated proteins in Chlamydomonas ( Shimogawara and Muto 1991 ); this likely suggests that the varied types of abiotic stress that induce superoxide would likewise increase the level of ubiquitinated proteins in Chlamydomonas . More recently, proteomic approaches have identified an accumulation of 20S core complex subunits in response to arsenate ( Walliwalagedara et al 2012 ) and cold stress in Chlamydomonas ( Valledor et al 2013 ). However, these previous studies did not determine whether the stressors increased proteasome activity, and therefore only partially implicate the UPP in mediating an abiotic stress response in Chlamydomonas .…”

Endoplasmic Reticulum-Mediated Protein Quality Control and Endoplasmic Reticulum-Associated Degradation Pathway Explain the Reduction of N-glycoprotein Level Under the Lead Stress

“…So far, the responses of C. reinhardtii to Pb stress were also studied, such as the role of phytochelatin in Pb detoxification ( Scheidegger et al, 2011 ), bioaccumulation and biosorption of Pb ( Stewart et al, 2015 ), and its compartmentalization in vacuoles ( Sánchez-Marín et al, 2014 ). Furthermore, it was documented that exposure to metals led to changes in the expression of proteins in C. reinhardtii ( Gillet et al, 2006 ; Walliwalagedara et al, 2012 ). However, it is still unknown how the Pb stress changes protein folding and quality control and the effects of the ERQC system and ERAD in C. reinhardtii under the Pb stress.…”