Identification of a thiosulfate utilization gene cluster from the green phototrophic bacterium Chlorobium limicola.
Identification of a thiosulfate utilization gene cluster from the green phototrophic bacterium Chlorobium limicola.
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DOI：
10.1021/bi011404m
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发表时间：
2002-03
期刊：
影响因子：
2.9
通讯作者：
Fabienne Verte;Vesna Kostanjevecki;L. D. Smet;Terrance E. Meyer;M. Cusanovich;J. V. Beeumen
中科院分区：
文献类型：
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作者：
Fabienne Verte;Vesna Kostanjevecki;L. D. Smet;Terrance E. Meyer;M. Cusanovich;J. V. Beeumen
氯菌是一种自养的绿色光养细菌，它利用还原的硫化合物将二氧化碳固定在光中。对于任何种类的细菌来说，硫化物、硫和硫代硫酸盐氧化的途径都没有确定的特征。然而，可溶性细胞色素c-551和黄细胞色素c （FCSD）先前在氯气中的酶分析中被认为与硫代硫酸盐和硫化物的氧化有关。我们现在已经做了一些关于还原硫化合物氧化的观察。(1) Western分析表明，限藻中可溶性细胞色素c-551受硫代硫酸盐调控，与硫代硫酸盐的利用作用一致。(2)膜结合的黄细胞色素c-硫化物脱氢酶（在其他物种中通常是一种可溶性蛋白质）是组成性的，不受硫化物的调节，而对于依赖硫化物的专一自养物种来说，这是预期的。(3)我们克隆了c-551基因，并发现了其他7个可能也参与硫代谢的基因，这些基因位于细胞色素c-551 （SoxA）基因附近。这些基因包括黄细胞色素c黄蛋白同源物（SoxF2），核苷酸酶同源物（SoxB），四个小蛋白（包括SoxX， SoxY和SoxZ）和硫醇-二硫交换蛋白同源物（SoxW）。(4)我们已经确定组成性表达的FCSD基因（soxEF1）位于基因组的其他位置。(5)通过数据库检索，我们发现8个硫代硫酸盐利用基因在tepidum Chlorobium基因组（www.tigr.org）中以相同的顺序聚集在一起。类似的硫代硫酸盐利用基因簇出现在至少六种其他细菌物种中，但可能另外包括罗丹斯和亚硫酸盐脱氢酶的基因。
Chlorobium is an autotrophic, green phototrophic bacterium which uses reduced sulfur compounds to fix carbon dioxide in the light. The pathways for the oxidation of sulfide, sulfur, and thiosulfate have not been characterized with certainty for any species of bacteria. However, soluble cytochrome c-551 and flavocytochrome c (FCSD) have previously been implicated in the oxidation of thiosulfate and sulfide on the basis of enzyme assays in Chlorobium. We have now made a number of observations relating to the oxidation of reduced sulfur compounds. (1) Western analysis shows that soluble cytochrome c-551 in Chlorobium limicola is regulated by thiosulfate, consistent with a role in the utilization of thiosulfate. (2) A membrane-bound flavocytochrome c-sulfide dehydrogenase (which is normally a soluble protein in other species) is constitutive and not regulated by sulfide as expected for an obligately autotrophic species dependent upon sulfide. (3) We have cloned the cytochrome c-551 gene from C. limicola and have found seven other genes, which are also presumably involved in sulfur metabolism and located near that for cytochrome c-551 (SoxA). These include genes for a flavocytochrome c flavoprotein homologue (SoxF2), a nucleotidase homologue (SoxB), four small proteins (including SoxX, SoxY, and SoxZ), and a thiol-disulfide interchange protein homologue (SoxW). (4) We have established that the constitutively expressed FCSD genes (soxEF1) are located elsewhere in the genome. (5) Through a database search, we have found that the eight thiosulfate utilization genes are clustered in the same order in the Chlorobium tepidum genome (www.tigr.org). Similar thiosulfate utilization gene clusters occur in at least six other bacterial species but may additionally include genes for rhodanese and sulfite dehydrogenase.