Identification and modification of biphenyl dioxygenase sequences that determine the specificity of polychlorinated biphenyl degradation
Identification and modification of biphenyl dioxygenase sequences that determine the specificity of polychlorinated biphenyl degradation
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DOI：
10.1128/aem.63.8.3096-3103.1997
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发表时间：
1997-08-01
影响因子：
4.4
通讯作者：
Erickson, BD
中科院分区：
文献类型：
--
作者：
Mondello, FJ;Turcich, MP;Erickson, BD
测定了一组多氯联苯（PCB）降解菌的PCB同系物特异性和联苯双加氧酶BphA部分序列。根据菌株降解17种多氯联苯同系物的能力，将菌株分为两组。菌株降解范围广泛的多氯联苯，但对二对位取代的多氯联苯的活性相对较弱，被指定为具有LB 400型特异性。被指定为具有KF707型特异性的菌株降解多氯联苯的范围要窄得多，但对某些二对位取代同系物具有很强的活性。这两种类型的菌株之间的BphA蛋白序列比较确定了四个区域（指定为I，II，III和IV），其中特定序列始终与宽或窄PCB底物特异性相关。LB 400和KF 707之间底物特异性的显著差异似乎主要是由于III和IV区突变的组合。改变LB 400 BphA亚基中的这些区域以对应于KF707序列中的那些区域，产生与KF707非常相似的窄底物特异性。一些单独的区域III内的突变被发现，以提高PCB降解活性，特别是对于二对位取代同系物。然而，活性的最大改善是由区域III中的多个氨基酸修饰引起的，这表明这些突变的作用是协同的。这些结果证明了通过联苯双加氧酶的序列修饰显著改善PCB氧化活性的能力。
The polychlorinated biphenyl (PCB) congener specificities and partial BphA sequences of biphenyl dioxygenase were determined for a set of PCB-degrading bacteria. The strains examined were categorized into two groups based on their ability to degrade 17 PCB congeners. Strains that degraded a broad range of PCBs but had relatively weak activity against di-para-substituted PCBs were designated as having an LB400-type specificity. Strains designated as having a KF707-type specificity degraded a much narrower range of PCBs but had strong activity against certain di-para-substituted congeners. BphA protein sequence comparisons between those two types of strains identified four regions (designated I, II, III, and IV) in which specific sequences were consistently associated with either broad or narrow PCB substrate specificity. The dramatic differences in substrate specificity between LB400 and KF707 appear to result primarily from a combination of mutations in regions III and IV. Altering these regions in the LB400 BphA subunit to correspond to those in the KF707 sequence produced a narrow substrate specificity very similar to that of KF707. Some individual mutations within region III alone were found to improve PCB degradative activity, especially for di-para-substituted congeners. However, the greatest improvements in activity resulted from multiple amino acid modifications in region III, suggesting that the effects of these mutations are cooperative. These results demonstrate the ability to significantly improve PCB oxidative activity through sequence modifications of biphenyl dioxygenase.