3,6-Dichlorosalicylate Catabolism Is Initiated by the DsmABC Cytochrome P450 Monooxygenase System in Rhizorhabdus dicambivorans Ndbn-20
3,6-Dichlorosalicylate Catabolism Is Initiated by the DsmABC Cytochrome P450 Monooxygenase System in Rhizorhabdus dicambivorans Ndbn-20
复制标题
3,6-二氯水杨酸分解代谢是由 DsmABC 细胞色素 P450 单加氧酶系统在根瘤菌 Ndbn-20 中启动的
DOI：
10.1128/aem.02133-17
复制
发表时间：
2017-12
影响因子：
4.4
通讯作者：
ong Jiang
中科院分区：
文献类型：
--
作者：
Na Li;Li Yao;Qin He;Jiguo Qiu;Dan Cheng;Derong Ding;Qing Tao;Jian He;Ji;ong Jiang
摘要 除草剂麦草畏的降解是通过去甲基化作用在二氯根杆菌 Ndbn-20 中形成 3,6-二氯水杨酸酯 (3,6-DCSA) 来引发的。在本研究中，筛选了 3,6-DCSA 降解缺陷突变体 Ndbn-20m。该突变体中丢失了 dsmR1DABCEFGR2 簇。该簇由 9 个基因组成，所有这些基因显然都是由 3,6-DCSA 诱导的。 DsmA 与已报道的三组分细胞色素 P450 系统的单加氧酶组分具有 30% 至 36% 的同一性，并在系统发育树中形成单系分支。 DsmB 和 DsmC 分别与报道的 [2Fe-2S] 铁氧还蛋白和铁氧还蛋白还原酶最密切相关。菌株 Ndbn-20 中 dsmA 的破坏导致 3,6-DCSA 降解失活。当将 dsmABC（而非单独的 dsmA）引入突变体 Ndbn-20m 和 Sphingobium quisquiliarum DC-2（无法降解水杨酸盐及其衍生物）时，它们获得了羟基化 3,6-DCSA 的能力。单晶X射线衍射表明，DsmABC催化的羟基化发生在3,6-DCSA的C-5位，生成3,6-二氯龙胆酸(3,6-DCGA)。此外，DsmD 与鞘氨醇单胞菌的 GtdA（一种龙胆酸和 3,6-DCGA 1,2-双加氧酶）具有 51% 的同一性。菌株 RW5。然而，与GtdA不同，纯化的DsmD在体外催化龙胆酸和3-氯龙胆酸的裂解，但不催化6-氯龙胆酸或3,6-DCGA。基于生物信息学分析和基因功能研究，提出了麦草畏在R. dicambivorans Ndbn-20中可能的分解代谢途径。重要性 麦草畏广泛用于控制多种阔叶杂草，是抗除草剂作物工程中很有前途的目标除草剂。因此，麦草畏的分解代谢受到越来越多的关注。细菌最初通过去甲基化作用使麦草畏矿化，生成 3,6-二氯水杨酸盐。然而，3,6-二氯水杨酸盐的分解代谢仍然未知。在这项研究中，我们克隆了一个基因簇dsmR1DABCEFGR2，该基因簇参与来自R. dicambivorans Ndbn-20的3,6-二氯水杨酸盐降解，证明细胞色素P450单加氧酶系统DsmABC负责3,6-二氯水杨酸盐的5-羟基化，并提出了麦草畏分解代谢途径。本研究为阐明麦草畏的分解代谢提供了基础，对麦草畏的生态毒理学研究具有一定的指导意义。此外，先前报道水杨酸盐的羟基化是由单组分黄素蛋白或三组分Rieske非血红素铁加氧酶催化的，而DsmABC是唯一使水杨酸盐及其甲基或氯取代衍生物羟基化的细胞色素P450单加氧酶系统。
ABSTRACT The degradation of the herbicide dicamba is initiated by demethylation to form 3,6-dichlorosalicylate (3,6-DCSA) in Rhizorhabdus dicambivorans Ndbn-20. In the present study, a 3,6-DCSA degradation-deficient mutant, Ndbn-20m, was screened. A cluster, dsmR1DABCEFGR2, was lost in this mutant. The cluster consisted of nine genes, all of which were apparently induced by 3,6-DCSA. DsmA shared 30 to 36% identity with the monooxygenase components of reported three-component cytochrome P450 systems and formed a monophyletic branch in the phylogenetic tree. DsmB and DsmC were most closely related to the reported [2Fe-2S] ferredoxin and ferredoxin reductase, respectively. The disruption of dsmA in strain Ndbn-20 resulted in inactive 3,6-DCSA degradation. When dsmABC, but not dsmA alone, was introduced into mutant Ndbn-20m and Sphingobium quisquiliarum DC-2 (which is unable to degrade salicylate and its derivatives), they acquired the ability to hydroxylate 3,6-DCSA. Single-crystal X-ray diffraction demonstrated that the DsmABC-catalyzed hydroxylation occurred at the C-5 position of 3,6-DCSA, generating 3,6-dichlorogentisate (3,6-DCGA). In addition, DsmD shared 51% identity with GtdA (a gentisate and 3,6-DCGA 1,2-dioxygenase) from Sphingomonas sp. strain RW5. However, unlike GtdA, the purified DsmD catalyzed the cleavage of gentisate and 3-chlorogentisate but not 6-chlorogentisate or 3,6-DCGA in vitro. Based on the bioinformatic analysis and gene function studies, a possible catabolic pathway of dicamba in R. dicambivorans Ndbn-20 was proposed. IMPORTANCE Dicamba is widely used to control a variety of broadleaf weeds and is a promising target herbicide for the engineering of herbicide-resistant crops. The catabolism of dicamba has thus received increasing attention. Bacteria mineralize dicamba initially via demethylation, generating 3,6-dichlorosalicylate. However, the catabolism of 3,6-dichlorosalicylate remains unknown. In this study, we cloned a gene cluster, dsmR1DABCEFGR2, involved in 3,6-dichlorosalicylate degradation from R. dicambivorans Ndbn-20, demonstrated that the cytochrome P450 monooxygenase system DsmABC was responsible for the 5-hydroxylation of 3,6-dichlorosalicylate, and proposed a dicamba catabolic pathway. This study provides a basis to elucidate the catabolism of dicamba and has benefits for the ecotoxicological study of dicamba. Furthermore, the hydroxylation of salicylate has been previously reported to be catalyzed by single-component flavoprotein or three-component Rieske non-heme iron oxygenase, whereas DsmABC was the only cytochrome P450 monooxygenase system hydroxylating salicylate and its methyl- or chloro-substituted derivatives.
登录
查看更多内容
两种谷胱甘肽依赖性 3,6-二氯龙胆酸脱卤酶的鉴定及其在除草剂麦草畏分解代谢中的作用 Rhizorhabdus dicambivorans Ndbn-20
影响因子：
4.4
作者：
Na Li;Ren-Lei Tong;Li Yao;Qing Chen;Xin Yan;De-Rong Ding;Ji-Guo Qiu;Jian He;Jian-dong Jiang
通讯作者：
Jian-dong Jiang
DOI：
10.1073/pnas.0805983105
发表时间：
2008-10-14
影响因子：
11.1
作者：
Cryle, Max J.;Schlichting, Ilme
通讯作者：
Schlichting, Ilme
影响因子：
3.2
作者：
N. Zhou;J. Al-Dulayymi;M. Baird;Peter A. Williams
通讯作者：
N. Zhou;J. Al-Dulayymi;M. Baird;Peter A. Williams
DOI：
--
发表时间：
--
期刊：
--
影响因子：
--
作者：
K. Livak;Thomas D. Schmittgen
通讯作者：
K. Livak;Thomas D. Schmittgen
影响因子：
7
作者：
Li, Ruiqiang;Zhu, Hongmei;Wang, Jun
通讯作者：
Wang, Jun