Regulation of sulfur metabolism, homeostasis and adaptive responses to sulfur limitation in cyanobacteria

Understanding of sulfur metabolism has reached a new dimension with comprehension of its molecular regulation; however, knowledge underlining the evolutionary perspective and dynamics of this metabolism in cyanobacteria is still limited. In this review, we provided a comprehensive overview of sulfur metabolism with special emphasis on cyanobacteria and discussed the biosynthesis of cysteine and its downstream sulfur containing metabolites. Here, we invested efforts to understand the possible regulatory mechanisms of cyanobacterial sulfur assimilation process by comparing with that of other bacteria and plants. The impact of sulfur limitation on the morpho-physiological, biochemical, and molecular responses in cyanobacteria was also elucidated. The present work reflected that the cyanobacterial sulfur assimilatory pathway is identical to that of bacteria and plants since all of them employ similar enzymes in the process; however, the regulatory mechanism may vary in cyanobacteria. This communication comprehends the recent progresses made in the field of cyanobacterial sulfur metabolism research along with a comparative account of sulfur metabolism in some related organisms. Therefore, this review not only gives a broad overview on cyanobacterial sulfur metabolism but also increases our understanding of the importance and evolutionary perspective of this crucial metabolism.