In marine ecosystems, the biosynthesis and catabolism of dimethylsulfoniopropionate (DMSP) by marine bacteria is critical to microbial survival and the ocean food chain. Furthermore, these processes also influence sulfur recycling and climate change. Recent studies using emerging genome sequencing data and extensive bioinformatics analysis have enabled us to identify new DMSP-related genes. Currently, seven bacterial DMSP lyases (DddD, DddP, DddY, DddK, DddL, DddQ and DddW), two acrylate degrading enzymes (DddA and DddC), and four demethylases (DmdA, DmdB, DmdC, and DmdD) have been identified and characterized in diverse marine bacteria. In this review, we focus on the biochemical properties of DMSP cleavage enzymes with special attention to DddD, DddA, and DddC pathways. These three enzymes function in the production of acetyl coenzyme A (CoA) and CO2 from DMSP. DddD is a DMSP lyase that converts DMSP to 3-hydroxypropionate with the release of dimethylsulfide. 3-Hydroxypropionate is then converted to malonate semialdehyde by DddA, an alcohol dehydrogenase. Then, DddC transforms malonate semialdehyde to acetyl-CoA and CO2 gas. DddC is a putative methylmalonate semialdehyde dehydrogenase that requires nicotinamide adenine dinucleotide and CoA cofactors. Here we review recent insights into the structural characteristics of these enzymes and the molecular events of DMSP degradation.

1. Introduction
2. Catabolism and Cleavage of DMSP
3. DddD (DMSP lyase)
4. DddA (putative 3HP dehydrogenase)
5. DddC (methylmalonate semialdehydedehydrogenase)

• Hackwon Do(Research Unit of Cryogenic Novel Material, Korea Polar Research Institute, Incheon 21990, Korea)
• Jisub Hwang(Research Unit of Cryogenic Novel Material, Korea Polar Research Institute, Incheon 21990, Korea, Department of Polar Sciences, University of Science and Technology, Incheon 21990, Korea)
• Sung Gu Lee(Research Unit of Cryogenic Novel Material, Korea Polar Research Institute, Incheon 21990, Korea, Department of Polar Sciences, University of Science and Technology, Incheon 21990, Korea)
• Jun Hyuck Lee(Research Unit of Cryogenic Novel Material, Korea Polar Research Institute, Incheon 21990, Korea, Department of Polar Sciences, University of Science and Technology, Incheon 21990, Korea) Corresponding author