Sulfurous Gases As Biological Messengers and Toxins: Comparative Genetics of Their Metabolism in Model Organisms

Abstract

Gasotransmitters are biologically produced gaseous signalling molecules. As gases with potent biological activities, they are toxic as air pollutants, and the sulfurous compounds are used as fumigants. Most investigations focus on medical aspects of gasotransmitter biology rather than toxicity toward invertebrate pests of agriculture. In fact, the pathways for the metabolism of sulfur containing gases in lower organisms have not yet been described. To address this deficit, we use protein sequences fromHomo sapiensto query Genbank for homologous proteins inCaenorhabditis elegans,Drosophila melanogaster, andSaccharomyces cerevisiae. InC. elegans, we find genes for all mammalian pathways for synthesis and catabolism of the three sulfur containing gasotransmitters, H2S, SO2and COS. The genes for H2S synthesis have actually increased in number inC. elegans. Interestingly,D. melanogasterand Arthropoda in general, lack a gene for 3-mercaptopyruvate sulfurtransferase, an enzym for H2S synthesis under reducing conditions.