Chapter Four - Functional Genomics of Metalloregulators in Cyanobacteria

Abstract Cyanobacterial metabolism relies on the activity of many enzymes and other proteins containing metal-rich cofactors that are absent in nonphotosynthetic organisms. Most of those micronutrients play key roles in or are associated to photosystems, respiratory electron transport chains and many enzymes involved in nitrogen metabolism. Since metal homeostasis is crucial for the ecological success of cyanobacteria, trace metal bio-uptake is strictly regulated by a number of metal-sensor proteins and regulatory proteins that often also contain metals. This chapter discusses functional studies undertaken to-date from a genomic point of view, as well as the main structural and mechanistic insights into the major families of metalloregulators in cyanobacteria. Reverse genetics, transcriptomics and other assays used for the identification of metal-regulated genes reveal interesting connections between metabolic networks and interactivity between major regulons. These data provide a better understanding of cyanobacterial physiology including maintenance of metal homeostasis, strategies to deal with different stresses and the basis of cyanotoxicity.