The dimethylsulfoxide (DMSO) reductase family of enzymes has many subfamilies catalysing unique biogeochemical reactions. It also has many uncharacterized subfamilies. Comparative genomics predicted one such subfamily to participate in a key step of the chlorine cycle because of a conserved genetic association with chlorite dismutase, implying they produce chlorite through chlorate or perchlorate reduction. We determined the activity of the uncharacterized enzyme by comparing strains in the phototrophic genus Rhodoplanes that encode either a typical perchlorate reductase or the uncharacterized enzyme. Rpl. piscinae and Rpl. elegans, which encode perchlorate reductase, grew by using perchlorate as an electron acceptor. In contrast, Rpl. roseus, which encodes the uncharacterized enzyme, grew by chlorate reduction but not by perchlorate reduction. This is the first report of perchlorate and chlorate being used as respiratory electron acceptors by phototrophs. When both chlorate and perchlorate were present, Rpl. roseus consumed only chlorate. Highly concentrated Rpl. roseus cells showed some perchlorate consumption, but chlorate consumption occurred at a 10‐fold higher rate. Together, these genomic and physiological data define a new group of chlorate reductases. Some organisms encode both this chlorate reductase and a perchlorate reductase, raising new questions about the physiology and evolution of chlorine oxyanion respiration.

中文翻译：

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DMSO还原酶钼氧化还原酶家族中未鉴定的进化枝是一种新型的氯酸盐还原酶。

酶的二甲基亚砜（DMSO）还原酶家族具有许多催化独特的生物地球化学反应的亚家族。它也有许多未知的亚科。比较基因组学预测这样的一个亚科将参与氯循环的关键步骤，因为它与亚氯酸盐歧化酶具有保守的遗传联系，这意味着它们通过氯酸盐或高氯酸盐的还原产生亚氯酸盐。我们通过比较光养菌属Rhodoplanes中编码典型高氯酸盐还原酶或未表征酶的菌株来确定未表征酶的活性。Rpl。piscinae和Rpl。线虫使用高氯酸盐作为电子受体，可以编码高氯酸盐还原酶。相反，Rpl。长春花，其编码未表征的酶，增长了氯酸盐减少但不是由高氯酸盐还原。这是高氯酸盐和氯酸盐被光养生物用作呼吸电子受体的第一个报道。当氯酸盐和高氯酸盐同时存在时，Rpl。玫瑰仅消耗氯酸盐。高度集中的Rpl。玫瑰花细胞显示出一些高氯酸盐的消耗，但是氯酸盐的消耗却高出10倍。这些基因组和生理数据共同定义了一组新的氯酸盐还原酶。一些生物同时编码这种氯酸盐还原酶和高氯酸盐还原酶，这引起了关于氯氧阴离子呼吸的生理学和进化的新问题。