S9-3 Mechanistic considerations of sulfide versus polysulfide mediated signaling events from a chemist’s perspective

Abstract

The underlying molecular mechanisms of sulfide-mediated signaling events are still poorly understood. This is in part due to the promiscuous chemical properties of sulfide, which poses serious challenges to investigators [1] . To date, from the chemical point of view, two major mechanisms are appreciated to play key roles in sulfide-signaling that are: (1) protein–cysteine sulfhydration and (2) interactions with molecules of NO-signaling pathways. In both cases we propose a major role for polysulfides that are sulfide oxidation products ( [2] , [3] , [4] , respectively), but other potential mechanisms will also be discussed. The biological roles of coordination- and redox-chemical reactions of sulfide with protein-metal centers are also increasingly recognized. These reactions mediate heme–protein functions in a protein specific manner. For example, our results with heme–peroxidase enzymes predict that sulfide will not only mediate the catalytic production of peroxidase-derived Reactive Oxygen Species (ROS), but also their chemical distribution [5] . This mechanism could represent a cross-talk between well-established redox-signaling events and sulfide-signaling. In addition, heme–enzymes (as well as their ROS products) can also catalyze (or trigger) sulfide oxidation reactions and thereby govern the partitioning of sulfide and its oxidative metabolites, which, owing to their different chemical properties, are proposed to result in different signaling events. Acknowledgements PN is grateful for financial supports from FP7-PEOPLE-2010-RG (Marie Curie International Reintegration Grant; grant No.: PIRG08-GA-2010-277006), The Hungarian National Science Foundation (OTKA; Grant No.: K 109843) and COST actions BM 1005 and BM 1203.