A new resource for the community: inventory of Chlamydomonas reinhardtii iron-sulfur proteins
Résumé
Iron-sulfur (Fe-S) cluster-containing proteins are present in all organisms and their number varies greatly. While they play essential roles in most subcellular compartments, and in many cellular processes (electron transport, enzyme catalysis, sensing and regulatory functions), the repertoire of Fe-S proteins was characterized only in a few model organisms. Compared to terrestrial plants, microalgae were reported to present additional Fe-S proteins, some of which for instance are involved in the anoxic metabolism (1). From the scientific literature and the well-described Fe-S proteomes from Escherichia coli (2) and Arabidopsis thaliana (3), we have defined a comprehensive list of more than 140 Fe-S proteins (~0.8% of protein-coding genes) in the model microalga Chlamydomonas reinhardtii, highlighting the expansion of some protein families. Sequence inspection allowed analyzing the presence of conserved amino acids involved in cluster binding. Most Fe-S proteins present the cluster(s) in the rhombic [Fe2S2] or the cubane forms [Fe4S4], except for few proteins presenting more complex clusters (e.g., hydrogenases and hybrid cluster proteins). Furthermore, most Fe-S proteins were found to localize predominantly in the cellular compartments of the chloroplast and the mitochondria. The resulting catalogue aims to provide a foundational dataset for the research community studying C. reinhardtii. This dataset will facilitate global analyses, e.g. analyzing how Fe-S cluster synthesis is regulated under diverse physiological conditions by exploiting current transcriptomic and/or proteomic data. It will also serve as a basis for cross-species comparisons and therefore further understanding Fe-S protein distribution at the evolutionary scale.