Selenium-binding Protein 1 (SBD1): A stress response regulator in Chlamydomonas reinhardtii

Abstract

Selenium-binding proteins (SBPs) represent a ubiquitous protein family implicated in various environmental stress responses, although the exact molecular and physiological role of the SBP family remains elusive. In this work, we report the identification and characterization of CrSBD1, an SBP homologue from the model microalgae Chlamydomonas reinhardtii. Growth analysis of the C. reinhardtii sbd1 mutant strain revealed that the absence of a functional CrSBD1 resulted in increased growth under mild oxidative stress conditions, although cell viability rapidly declined at higher H2O2 concentrations. Furthermore, a combined global transcriptomic and metabolomic analysis indicated that the sbd1 mutant exhibited a dramatic quenching of the molecular and biochemical responses upon H2O2-induced oxidative stress when compared to the wild type. Our results indicate that CrSBD1 represents a cell regulator, which is involved in the modulation of C. reinhardtii early responses to oxidative stress. We assert that CrSBD1 acts as a member of an extensive and conserved protein-protein interaction network including Fructose-bisphosphate aldolase 3 (CrFBA3), Cysteine endopeptidase 2 (CrCEP2), and Glutaredoxin 6 (CrGRX6) proteins, as indicated by yeast two-hybrid assays.

Global omics study of Tetraselmis chuii reveals time-related metabolic adaptations upon oxidative stress

“…Higher concentrations led to an immediate dramatic reduction in cell viability and the eventual collapse of the cultures. This quick reaction to H 2 O 2 corroborates with the sensing ability of green microalga C. reinhardtii , whereas a higher H 2 O 2 dosage up to 2-mM H 2 O 2 was required for reducing cell viability (Koletti et al 2022 ). This observation highlights the differences among green microalgal cells, with T. chuii being more sensitive to oxidative stress.…”

“…Several stressors can be utilized for the induction of oxidative stress, including hydrogen peroxide (Qiao et al 2021 ). In this scenario, it has been reported that the green microalga Chlamydomonas reinhardtii responded by inducing global alterations in its cellular and metabolic machinery within 6 h upon H 2 O 2 -induced oxidative stress, a regulatory process involving the Cr SBP selenium-binding protein (Koletti et al 2022 ). Similarly, H 2 O 2 -induced oxidative stress resulted in the differential regulation of several transcripts in C. reinhardtii (Blaby et al 2015 ).…”

Evolutionary Aspects of Selenium Binding Protein (SBP)

“…2 ) is a structural perspective based on sequence phylogenies and does not reflect any known functional diversification of SBPs, as a precise molecular function is limited to just a few instances, such as A. thaliana , C. elegans and H. sapiens. The C. reinhardtii SBP homolog was recently characterized as a novel stress sensor (Koletti et al 2022 ), while the human homolog plays crucial role in cancer development (Bansal et al 1990 ; Xia et al 2011 ; Huang et al 2012 ; Ansong et al 2015 ). However, the only known function is based on bacterial SBP56 which is characterized as a Cu-dependent methanethiol oxidase (MTO) (Eyice et al 2018 ).…”

“…Moreover, interactions of SBP1 with certain proteins in Arabidopsis are also conserved in C. reinhardtii . The same study revealed that SBP1 is involved in redox early sensing and triggering of the subsequent cellular responses via protein–protein interactions (Koletti et al 2022 ).…”

The SAH7 Homologue of the Allergen Ole e 1 Interacts with the Putative Stress Sensor SBP1 (Selenium-Binding Protein 1) in Arabidopsis thaliana

“…Our results indicated that Cr SBD1 represents a cell regulator, which is involved in the modulation of Chlamydomonas reinhardtii ’s early responses to oxidative stress. We asserted that Cr SBD1 acts as a member of an extensive and conserved protein–protein interaction network in C. reinhardtii , including Fructose-bisphosphate aldolase 3, Cysteine endopeptidase 2, and Glutaredoxin 6 proteins, as indicated by yeast two-hybrid assays [ 19 ].…”