Fe-S protein synthesis in green algae mitochondria

MARCHETTI ACOSTA, NOELIA; TERENZI, AGUSTINA; PAGANI, MARIA A.; DIEGO FABIAN GOMEZ CASATI; BARCHIESI, JULIETA; BUSI, MARIA VICTORIA

Virtual

Congreso; LVII SAIB Meeting - XVI SAMIGE Meeting; 2021

SAIB - SAMIGE

Iron is an essential micronutrient for all aerobic organisms and it is present in many proteins as a cofactor, forming part of the Fe-S clusters. These groups are present in numerous proteins that participate in different metabolic pathways such as photosynthesis and respiration, regulation of gene expression, protein translation, maintenance of DNA integrity, and in metabolic pathways related to the assimilation of nitrogen, sulfur and iron. Although there are several reports that have characterized the function and regulation of genes and proteins that participate in the production of Fe-S groups in bacteria, yeasts and humans, little is known about the presence and function of these genes in photosynthetic organisms, especially in algae. Studies carried out in A. thaliana demonstrated that there are three metabolic pathways for the assembly of Fe-S groups: (i) the SUF (sulfur mobilization) pathway in chloroplasts, (ii) the CIA pathway of assembly of Fe-S groups in the cytosol, and (iii) the ISC pathway, mitochondrial iron-sulfur group. The SUF and ISC machines perform the synthesis of Fe-S groups in three basic stages. In the first stage, S is obtained from the reaction catalyzed by a cysteine desulfurase, NFS, and combines with Fe in a Scaffold protein for the de novo synthesis of groups (2Fe-2S). In a second stage, the Fe-S group is released from the Scaffold with the help of chaperones and co-chaperones and bound by a protein transfer. The third step is less known and comprises the conversion of (2Fe-2S) into groups (4Fe-4S) and the insertion into apoproteins. In this work we investigated the presence of homologous genes which code for scaffold proteins, regulatory proteins, chaperones and co-chaperones of the Fe-S group synthesis pathway in chlorophytes. For this, we carried out a search for sequence similarity of amino acids using each ´protein sequence from ISC proteins found in A. thaliana as a query in the Uniprot, Phytozome and NCBI databases. For all the sequences analyzed, we identified several homologues which presented high percentages of identity respect to the query sequence. We also performed alignments of all the chlorophyte ISC sequences plus the A. thaliana homologues using Clustal Omega and we detect that the critical residuals for the function of each protein are highly conserved. To analyze the cellular location of the proteins, we used the Depp-Loc1.0 server. The results showed that many of the proteins present cytoplasmic localization, while they would have a plastidic localization. To a lesser extent, we found proteins that would have a dual location in the nucleus and cytoplasm.