Comparative proteomic analysis of Chlamydomonas reinhardtii control and a salinity-tolerant strain revealed a differential protein expression pattern

Abstract

Proteins involved in membrane transport and trafficking, stress and defense, iron uptake and metabolism, as well as proteolytic enzymes, were remarkably up-regulated in the salinity-tolerant strain of Chlamydomonas reinhardtii. Excessive concentration of NaCl in the environment can cause adverse effects on plants and microalgae. Successful adaptation of plants to long-term salinity stress requires complex cellular adjustments at different levels from molecular, biochemical and physiological processes. In this study, we developed a salinity-tolerant strain (ST) of the model unicellular green alga, Chlamydomonas reinhardtii, capable of growing in medium containing 300 mM NaCl. Comparative proteomic analyses were performed to assess differential protein expression pattern between the ST and the control progenitor cells. Proteins involved in membrane transport and trafficking, stress and defense, iron uptake and metabolism, as well as protein degradation, were remarkably up-regulated in the ST cells, suggesting the importance of these processes in acclimation mechanisms to salinity stress. Moreover, 2-DE-based proteomic also revealed putative salinity-specific post-translational modifications (PTMs) on several important housekeeping proteins. Discussions were made regarding the roles of these differentially expressed proteins and the putative PTMs in cellular adaptation to long-term salinity stress.

Salinity Stress Responses and Adaptation Mechanisms in Eukaryotic Green Microalgae

“…Upregulation of membrane transport proteins can confer tolerance to high salinity in halotolerant algae species by actively transporting K + ions through membrane transport proteins. Salt adapted mutants of C. reinhardtii showed enhanced expression of multiple membrane transport proteins [55]. Genes for K + ion transport were significantly upregulated when salt sensitive C. reinhardtii cells were under salt stress [48], possibly compensating the disruption in K + uptake caused due to high concentration of Na + ions.…”

Quantitative proteomic comparison of salt stress in Chlamydomonas reinhardtii and the snow alga Chlamydomonas nivalis reveals mechanisms for salt-triggered fatty acid accumulation via reallocation of carbon resources

“…This may explain why it is unchanged where it is needed in C. reinhardtii but decreased in C. nivalis where maintenance of PSII is not required. Additionally, HSP70B has previously been shown to increase under salinity stress in salt-adapted C. reinhardtii cells, suggesting it may have a role in salinity tolerance [ 47 ]. Therefore, whilst the reduced abundance of heat shock proteins in C. nivalis may seem unexpected, this phenomenon has been shown to occur in Chlamydomonas during stress.…”

A Data-Independent-Acquisition-based proteomic approach towards understanding the acclimation strategy ofMicrochloropsis gaditanaCCMP526 in hypersaline conditions

“…These proteins are involved in maintaining the redox status in higher plants (Chen et al, 2009; Kav et al, 2004; Sugimoto & Takeda, 2009). Likewise, the SOD level was increased in the halotolerant alga Dunaliella salina (Wei et al, 2017) and in a salinity tolerant strain of Chlamydomonas reinhardtii (Sithtisarn et al, 2017). Anti-oxidant proteins help to maintain the ROS level inside the cell, and accumulation of such proteins have been found in salinity treated plants (Miller et al, 2010).…”

“…has been studied to understand the molecular basis behind tolerance to high saline conditions (Katz et al, 2007; Wei et al, 2017). Sithtisarn et al (2017) performed comparative proteome analysis of a control, and a salinity tolerant strain of Chlamydomonas reinhardtii to understand the salinity tolerance mechanism involved. Alterations in proteome of terrestrial plants have also been extensively studied (Aghaei et al, 2008; Silveira & Carvalho, 2016).…”