Bach Institute of Biochemistry, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia.
Biochemistry (Mosc). 2021 Mar;86(3):361-369. doi: 10.1134/S0006297921030111.
Flavocytochrome c sulfide dehydrogenase (FCC) is one of the central enzymes of the respiratory chain in sulfur-oxidizing bacteria. FCC catalyzes oxidation of sulfide and polysulfide ions to elemental sulfur accompanied by electron transfer to cytochrome c. The catalytically active form of the enzyme is a non-covalently linked heterodimer composed of flavin- and heme-binding subunits. The Thioalkalivibrio paradoxus ARh1 genome contains five copies of genes encoding homologous FCCs with an amino acid sequence identity from 36 to 54%. When growing on thiocyanate or thiosulfate as the main energy source, the bacterium synthesizes products of different copies of FCC genes. In this work, we isolated and characterized FCC synthesized during the growth of Tv. paradoxus on thiocyanate. FCC was shown to oxidize exclusively sulfide but not other reduced sulfur compounds, such as thiosulfate, sulfite, tetrathionate, and sulfur, and it also does not catalyze the reverse reaction of sulfur reduction to sulfide. Kinetic parameters of the sulfide oxidation reaction are characterized.
黄素细胞色素 c 硫化物脱氢酶 (FCC) 是硫氧化细菌呼吸链中的核心酶之一。FCC 催化硫化物和多硫化物离子氧化为单质硫，同时将电子转移到细胞色素 c。酶的催化活性形式是非共价连接的异源二聚体，由黄素和血红素结合亚基组成。脱硫弧菌 ARh1 基因组包含五个编码同源 FCC 的基因拷贝，其氨基酸序列同一性为 36%至 54%。当以硫氰酸盐或硫代硫酸盐作为主要能源生长时，细菌会合成不同拷贝 FCC 基因的产物。在这项工作中，我们分离并表征了 Tv. paradoxus 在硫氰酸盐上生长时合成的 FCC。结果表明，FCC 仅能氧化硫化物，而不能氧化其他还原态硫化合物，如硫代硫酸盐、亚硫酸盐、连四硫酸盐和硫，也不能催化硫还原为硫化物的逆反应。还对硫化物氧化反应的动力学参数进行了表征。
