Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma 73019-0245.
Appl Environ Microbiol. 1990 Oct;56(10):2999-3005. doi: 10.1128/aem.56.10.2999-3005.1990.
We studied the transformation of halogenated benzoates by cell extracts of a dehalogenating anaerobe, "Desulfomonile tiedjei." We found that cell extracts possessed aryl reductive dehalogenation activity. The activity was heat labile and dependent on the addition of reduced methyl viologen, but not on that of reduced NAD, NADP, flavin mononucleotide, flavin adenine dinucleotide, desulfoviridin, cytochrome c(3), or benzyl viologen. Dehalogenation activity in extracts was stimulated by formate, CO, or H(2), but not by pyruvate plus coenzyme A or by dithionite. The pH and temperature optima for aryl dehalogenation were 8.2 and 35 degrees C, respectively. The rate of dehalogenation was proportional to the amount of protein in the assay mixture. The substrate specificity of aryl dehalogenation activity for various aromatic compounds in "D. tiedjei" cell extracts was identical to that of whole cells, except differences were observed in the relative rates of halobenzoate transformation. Dehalogenation was 10-fold greater in "D. tiedjei" extracts prepared from cells cultured in the presence of 3-chlorobenzoate, suggesting that the activity was inducible. Aryl reductive dehalogenation in extracts was inhibited by sulfite, sulfide, and thiosulfate, but not sulfate. Experiments with combinations of substrates suggested that cell extracts dehalogenated 3-iodobenzoate more readily than either 3,5-dichlorobenzoate or 3-chlorobenzoate. Dehalogenation activity was found to be membrane associated. This is the first report characterizing aryl dehalogenation activity in cell extracts of an obligate anaerobe.
我们研究了脱卤厌氧菌“脱硫单胞菌 tiedjei”细胞提取物对卤代苯甲酸的转化。我们发现细胞提取物具有芳基还原脱卤活性。该活性对热不稳定，依赖于还原甲基紫精的添加，但不依赖于还原 NAD、NADP、黄素单核苷酸、黄素腺嘌呤二核苷酸、脱硫黄素、细胞色素 c(3)或苯甲酰基紫精。提取物中的脱卤活性受甲酸盐、CO 或 H2 刺激，但不受丙酮酸盐加辅酶 A 或连二亚硫酸盐刺激。芳基脱卤的 pH 和温度最佳值分别为 8.2 和 35°C。脱卤的速率与测定混合物中的蛋白质量成正比。“D. tiedjei”细胞提取物中各种芳香族化合物的芳基脱卤活性的底物特异性与完整细胞相同，只是卤代苯甲酸的转化相对速率存在差异。在含有 3-氯苯甲酸的培养基中培养的细胞制备的“D. tiedjei”提取物中，脱卤活性增加了 10 倍，表明该活性可诱导。亚硫酸盐、硫化物和硫代硫酸盐抑制提取物中的芳基还原脱卤，但硫酸盐不抑制。用组合底物进行的实验表明，细胞提取物比 3,5-二氯苯甲酸或 3-氯苯甲酸更容易脱卤 3-碘苯甲酸。脱卤活性与膜相关。这是首次报道描述严格厌氧菌细胞提取物中的芳基脱卤活性。
