Journal Article

Two radical-dependent mechanisms for anaerobic degradation of the globally abundant organosulfur compound dihydroxypropanesulfonate

Wei, Yifeng, Teng, Lin, Chen, Jiawei, Li, Yaxin, Liu, Yanhong, Zhai, Weixiang, Lu, Qiang, Ang, Ee Lui, Liu, Yangping, Zhao, Huimin, Lin, Lianyun, Yin, Jinyu, Zheng, Yuchun, Yuchi, Zhiguang, Zhang, Yan, Liu, Jiayi, Xu, Runyao, Cao, Peng

2020

Overview

2(S)-dihydroxypropanesulfonate (DHPS) is a microbial degradation product of 6-deoxy-6-sulfo-d-glucopyranose (sulfoquinovose), a component of plant sulfolipid with an estimated annual production of 1010 tons. DHPS is also at millimolar levels in highly abundant marine phytoplankton. Its degradation and sulfur recycling by microbes, thus, play important roles in the biogeochemical sulfur cycle. However, DHPS degradative pathways in the anaerobic biosphere are not well understood. Here, we report the discovery and characterization of two O₂-sensitive glycyl radical enzymes that use distinct mechanisms for DHPS degradation. DHPS-sulfolyase (HpsG) in sulfate- and sulfite-reducing bacteria catalyzes C–S cleavage to release sulfite for use as a terminal electron acceptor in respiration, producing H₂S. DHPS-dehydratase (HpfG), in fermenting bacteria, catalyzes C–O cleavage to generate 3-sulfopropionaldehyde, subsequently reduced by the NADH-dependent sulfopropionaldehyde reductase (HpfD). Both enzymes are present in bacteria from diverse environments including human gut, suggesting the contribution of enzymatic radical chemistry to sulfur flux in various anaerobic niches.

• Publisher: National Academy of Sciences
• Subject: Alkanesulfonates - metabolism / Anaerobiosis / Bacteria / Bacteria - enzymology / Bacterial Proteins - metabolism / Biochemistry / Biodegradation / Biogeochemical cycles / Biological Sciences / Biosphere / Cleavage / Computational Biology / Dehydration / Enzyme Assays / Enzymes / Gastrointestinal Microbiome - physiology / Hydrogen sulfide / Hydrogen Sulfide - metabolism / Hydrogen Sulfide - toxicity / Methylglucosides - metabolism / Microbial degradation / Microorganisms / NADH / Nicotinamide adenine dinucleotide / Organosulfur compounds / Phytoplankton / Reductase / Reductases / Sulfates / Sulfite / Sulfite-reducing bacteria / Sulfur / Sulfur - metabolism / Sulfur cycle