title: Diversity and regulation of ATP sulfurylase in photosynthetic organisms.
abstract: ATP sulfurylase (ATPS) catalyzes the first committed step in the sulfate assimilation pathway, the activation of sulfate prior to its reduction. ATPS has been studied in only a few model organisms and even in these cases to a much smaller extent than the sulfate reduction and cysteine synthesis enzymes. This is possibly because the latter were considered of greater regulatory importance for sulfate assimilation. Recent evidences (reported in this paper) challenge this view and suggest that ATPS may have a crucial regulatory role in sulfate assimilation, at least in algae. In the ensuing text, we summarize the current knowledge on ATPS, with special attention to the processes that control its activity and gene(s) expression in algae. Special attention is given to algae ATPS proteins. The focus on algae is the consequence of the fact that a comprehensive investigation of ATPS revealed that the algal enzymes, especially those that are most likely involved in the pathway of sulfate reduction to cysteine, possess features that are not present in other organisms. Remarkably, algal ATPS proteins show a great diversity of isoforms and a high content of cysteine residues, whose positions are often conserved. According to the occurrence of cysteine residues, the ATPS of eukaryotic algae is closer to that of marine cyanobacteria of the genera Synechococcus and Prochlorococcus and is more distant from that of freshwater cyanobacteria. These characteristics might have evolved in parallel with the radiation of algae in the oceans and the increase of sulfate concentration in seawater.
authors.affiliation: Laboratory of Algal and Plant Physiology, Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche Ancona, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Prioretti
authors.affiliation: Aix-Marseille Université Centre National de la Recherche Scientifique, BL' Unité de Bioénergétique et Ingénierie des Protéines UMR 7281 Marseille, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Gontero
authors.affiliation: Centre for Organismal Studies, University of Heidelberg Heidelberg, Germany.
authors.forename: Ruediger
authors.initials: R
authors.lastname: Hell
authors.affiliation: Laboratory of Algal and Plant Physiology, Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche Ancona, Italy ; Institute of Microbiology Academy of Sciences of the Czech Republic Trebon, Czech Republic.
authors.forename: Mario
authors.initials: M
authors.lastname: Giordano
keywords: ATPS; algae; algal evolution; cysteine; redox regulation; sulfur metabolism