Diversity and roles of cysteine desulfurases in photosynthetic organisms

A review describing the biochemical and structural properties as well as physiological roles of cysteine desulfurases in sulfur-dependent biosynthetic pathways in photosynthetic organisms, focusing particularly on Arabidopsis isoforms. As sulfur is part of many essential protein cofactors such as iron-sulfur clusters, molybdenum cofactors, or lipoic acid, its mobilization from cysteine represents a fundamental process. The abstraction of the sulfur atom from cysteine is catalysed by highly conserved pyridoxal 5MODIFIER LETTER PRIME-phosphate-dependent enzymes called cysteine desulfurases. The desulfuration of cysteine leads to the formation of a persulfide group on a conserved catalytic cysteine and the concomitant release of alanine. Sulfur is then transferred from cysteine desulfurases to different targets. Numerous studies have focused on cysteine desulfurases as sulfur-extracting enzymes for iron-sulfur cluster synthesis in mitochondria and chloroplasts but also for molybdenum cofactor sulfuration in the cytosol. Despite this, knowledge about the involvement of cysteine desulfurases in other pathways is quite rudimentary, particularly in photosynthetic organisms. In this review, we summarize current understanding of the different groups of cysteine desulfurases and their characteristics in terms of primary sequence, protein domain architecture, and subcellular localization. In addition, we review the roles of cysteine desulfurases in different fundamental pathways and highlight the gaps in our knowledge to encourage future work on unresolved issues especially in photosynthetic organisms.

Automated summary

This review focuses on the biochemical, structural, and physiological roles of cysteine desulfurases in sulfur-dependent biosynthetic pathways in photosynthetic organisms, with particular emphasis on Arabidopsis isoforms. Cysteine desulfurases are highly conserved enzymes that catalyze the extraction of sulfur from cysteine, leading to the formation of persulfide groups on catalytic cysteine residues. The sulfur is then transferred to various targets, including iron-sulfur clusters and molybdenum cofactors. While there is extensive knowledge about cysteine desulfurases in some pathways, such as iron-sulfur cluster synthesis, our understanding of their involvement in other pathways, especially in photosynthetic organisms, is limited. This review summarizes the current knowledge of cysteine desulfurases and highlights gaps in understanding, emphasizing the need for future research in this area.