Proteomic analysis of salinity-stressed Chlamydomonas reinhardtii revealed differential suppression and induction of a large number of important housekeeping proteins

Abstract

Salinity stress is one of the most common abiotic stresses that hamper plant productivity worldwide. Successful plant adaptations to salt stress require substantial changes in cellular protein expression. In this work, we present a 2-DE-based proteomic analysis of a model unicellular green alga, Chlamydomonas reinhardtii, subjected to 300 mM NaCl for 2 h. Results showed that, in addition to the protein spots that showed partial up- or down-regulation patterns, a number of proteins were exclusively present in the proteome of the control cells, but were absent from the salinity-stressed samples. Conversely, a large number of proteins exclusively appeared in the proteome of the salinity-stressed samples. Of those exclusive proteins, we could successfully identify, via LC-MS/MS, 18 spots uniquely present in the control cells and 99 spots specific to NaCl-treated cells. Interestingly, among the salt-exclusive protein spots, we identified several important housekeeping proteins like molecular chaperones and proteins of the translation machinery, suggesting that they may originate from post-translational modifications rather than from de novo biosynthesis. The possible role and the salt-specific modification of these proteins by salinity stress are discussed.

Novel insights into salinity-induced lipogenesis and carotenogenesis in the oleaginous astaxanthin-producing alga Chromochloris zofingiensis: a multi-omics study

“…Salt stress is a well-known abiotic stress that has multiplex effects on photosynthetic eukaryotes, such as photosynthesis impairment, ROS accumulation, protein turnover, glycerol build-up, oil accumulation, or carotenogenesis, depending on organisms [9,28,29,40,[85][86][87]. The adverse impact of salt stress on photosynthesis has been observed for freshwater algae particularly the model alga Chlamydomonas reinhardtii, leading to attenuated biomass production in response to salt stress [28,40,88].…”

Evolution of salt tolerance in a laboratory reared population of Chlamydomonas reinhardtii

“…A study of proteins found exclusively in C. reinhardtii cells shocked with 300 mM NaCl and analysed after 2 h incubation showed that 13% of the proteins were involved in protein translation, including eukaryotic initiation factor EIF3I and elongation factor Tu. This is consistent with previous work done with Dunaliella salina showing an enhancement under salt stress of expression of genes encoding components of the translation machinery (Yokthongwattana et al ., ).…”

“…Previous work done on the impact of hyperosmolarity on C. reinhardtii Existing research on C. reinhardtii shows that at the morphological level, 150 mM NaCl salt stress leads to flagellar resorption, reduction in cell size, slower growth rates and palmelloid (i.e., clumped) morphology (Neelam and Subramanyam, 2013). The major metabolic impacts of salt stress are a need for energy to maintain ion homeostasis, the scavenging of reactive oxygen species (ROS) by antioxidant enzymes and the upregulation of heatshock proteins and chaperones to aid protein renaturation due to misfolding or aggregation (Yokthongwattana et al, 2012). The short-term response by C. reinhardtii and plants to salt stress involves activation of phospholipid signaling leading, for example, to the accumulation of phosphatidic acid (PA).…”

Sensitivity of Antarctic freshwater algae to salt stress assessed by fast chlorophyll fluorescence transient

“…Involvement of physiological mechanisms that improve salt resistance of algae, such as e.g. ABA content (Yoshida et al 2004), sugar degradation and glycerol production (Miyasaka et Ikeda 1997), regulation of lipid biosynthesis (Lu et al 2012, Meijer et al 2001, and specific proteins expression (Yokthongwattana et al 2012, Mastrobouni et al 2012) might be also considered.…”