856 / 2024-09-19 16:36:10

Novel dimethylsulfoniopropionate (DMSP) biosynthesis enzymes in diverse marine bacteria, cyanobacteria and abundant algae

dimethylsulfoniopropionate,bloom-forming Pelagophyceae,climate-cooling gas,sulfur cycling

Dimethylsulfoniopropionate (DMSP) is an abundant marine organosulfur compound with roles in stress protection, chemotaxis, nutrient and

sulfur cycling and climate regulation. Here we report the discovery of a bifunctional DMSP biosynthesis enzyme, DsyGD, in the transamination

pathway of the rhizobacterium Gynuella sunshinyii and some filamentous cyanobacteria not previously known to produce DMSP. DsyGD produces

DMSP through its N-terminal DsyG methylthiohydroxybutyrate S-methyltransferase and C-terminal DsyD dimethylsulfoniohydroxybutyrate

decarboxylase domains. Phylogenetically distinct DsyG-like proteins, termed DSYE, with methylthiohydroxybutyrate S-methyltransferase

activity were found in diverse and environmentally abundant algae, comprising a mix of low, high and previously unknown DMSP producers. Algae containing DSYE, particularly bloom-forming Pelagophyceae species, were globally more abundant DMSP producers than those with previously described DMSP synthesis genes. This work greatly increases the number and diversity of predicted DMSP-producing organisms and highlights the importance of Pelagophyceae and other DSYE-containing algae in global DMSP production and sulfur cycling.