PDF(Pubmed)
Abstract：
Chirality, a fundamental property of matter, is often overlooked in the studies of marine organic matter cycles. Dihydroxypropanesulfonate (DHPS), a globally abundant organosulfur compound, serves as an ecologically important currency for nutrient and energy transfer from phytoplankton to bacteria in the ocean. However, the chirality of DHPS in nature and its transformation remain unclear. Here, we developed a novel approach using chiral phosphorus-reagent labeling to separate DHPS enantiomers. Our findings demonstrated that at least one enantiomer of DHPS is present in marine diatoms and coccolithophores, and that both enantiomers are widespread in marine environments. A novel chiral-selective DHPS catabolic pathway was identified in marine Roseobacteraceae strains, where HpsO and HpsP dehydrogenases at the gateway to DHPS catabolism act specifically on R-DHPS and S-DHPS, respectively. R-DHPS is also a substrate for the dehydrogenase HpsN. All three dehydrogenases generate stable hydrogen bonds between the chirality-center hydroxyls of DHPS and highly conserved residues, and HpsP also form coordinate-covalent bonds between the chirality-center hydroxyls and Zn2+, which determines the mechanistic basis of strict stereoselectivity. We further illustrated the role of enzymatic promiscuity in the evolution of DHPS metabolism in Roseobacteraceae and SAR11. This study provides the first evidence of chirality\'s involvement in phytoplankton-bacteria metabolic currencies, opening a new avenue for understanding the ocean organosulfur cycle.
摘要：
Chirality,物质的基本属性，在海洋有机物循环研究中经常被忽视。二羟基丙磺酸盐(DHPS),一种全球丰富的有机硫化合物，作为营养和能量从浮游植物转移到海洋中的细菌的生态重要货币。然而,DHPS在自然界中的手性及其转化尚不清楚。这里,我们开发了一种使用手性磷试剂标记分离DHPS对映体的新方法。我们的发现表明，至少有一种DHPS的对映体存在于海洋硅藻和球藻中，这两种对映体在海洋环境中都很普遍。在海洋玫瑰杆菌科菌株中鉴定出一种新的手性选择性DHPS分解代谢途径，其中DHPS分解代谢网关处的HpsO和HpsP脱氢酶特异性作用于R-DHPS和S-DHPS，分别。R-DHPS也是脱氢酶HpsN的底物。所有三种脱氢酶都在DHPS的手性中心羟基和高度保守的残基之间产生稳定的氢键，和HpsP还在手性中心羟基和Zn2之间形成配位共价键，这决定了严格立体选择性的机理基础。我们进一步说明了酶促混杂在玫瑰杆菌科和SAR11中DHPS代谢进化中的作用。这项研究提供了第一个证据的手性参与浮游植物-细菌代谢货币,为理解海洋有机硫循环开辟了一条新途径。
