Della-Negra Oriane, Le Cacher de Bonneville Brieuc, Chaussonnerie Sébastien, Le Paslier Denis, Frison Gilles, Saaidi Pierre-Loïc
Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, 91057 Evry, France.
Laboratoire de Chimie Moléculaire, Ecole Polytechnique, CNRS, IP Paris, 91128 Palaiseau, France.
ACS Omega. 2021 Mar 9;6(11):7512-7523. doi: 10.1021/acsomega.0c06041. eCollection 2021 Mar 23.
Microbiological reductive sulfidation (RS) has rarely been documented, although it represents an efficient strategy for thiol formation. In this work, we reported on the sulfate-respiring bacterium sp.86 that has previously demonstrated RS activity toward the pesticide chlordecone. The purpose of this study was to assess its substrate versatility using a set of 28 carbonyls, to compare with chemical RS and to rationalize the observed trends using a dual experimental and theoretical approach. The chemical RS generally proceeds in two steps (S/O exchange using a sulfur donor like PS, reduction of the thione intermediate). Intriguingly, chlordecone was found to be converted into chlordecthiol following the first step. Hence, we designed a protocol and applied it to the 28 substrates to assess their propensity to be directly converted into thiols with the PS treatment alone. Finally, we performed density functional theory calculations on these carbonyls and their thiocarbonyl derivatives to build a set of structural, electronic, and thermodynamic parameters. The results showed that chemical and microbiological RS probably involved two distinct mechanisms. Chemically, we observed that several carbonyls, possessing electron-withdrawing groups and/or aromatic rings, were directly transformed into thiols in the presence of PS. The correlation obtained with the electron affinity of the thiones led us to conclude that a probable single-electron reductive transfer occurred during the first step. We also found that sp.86 transformed a variety of aldehydes and ketones, without ever detecting thiones. No significant correlation was observed with the calculated parameters, but a relationship between aldehyde RS biotransformation and bacterial growth was observed. Differences in selectivity with chemical RS open the way for further applications in organic synthesis.
微生物还原硫化作用（RS）鲜有文献记载，尽管它是一种形成硫醇的有效策略。在本研究中，我们报道了硫酸盐呼吸细菌sp.86，该细菌先前已证明对农药十氯酮具有RS活性。本研究的目的是使用一组28种羰基化合物评估其底物通用性，与化学RS进行比较，并通过实验和理论双重方法对观察到的趋势进行合理化分析。化学RS一般分两步进行（使用硫供体如PS进行S/O交换，还原硫酮中间体）。有趣的是，发现十氯酮在第一步后转化为十氯硫醇。因此，我们设计了一个方案并将其应用于这28种底物，以评估它们仅通过PS处理直接转化为硫醇的倾向。最后，我们对这些羰基化合物及其硫羰基衍生物进行了密度泛函理论计算，以建立一组结构、电子和热力学参数。结果表明，化学和微生物RS可能涉及两种不同的机制。在化学方面，我们观察到几种具有吸电子基团和/或芳香环的羰基化合物在PS存在下直接转化为硫醇。与硫酮电子亲和力的相关性使我们得出结论，第一步可能发生了单电子还原转移。我们还发现sp.86转化了多种醛和酮，从未检测到硫酮。未观察到与计算参数的显著相关性，但观察到醛RS生物转化与细菌生长之间的关系。与化学RS在选择性上的差异为有机合成中的进一步应用开辟了道路。
