Involvement of a Novel ABC Transporter and Monoalkyl Phthalate Ester Hydrolase in Phthalate Ester Catabolism by Rhodococcus jostii RHA1
Involvement of a Novel ABC Transporter and Monoalkyl Phthalate Ester Hydrolase in Phthalate Ester Catabolism by Rhodococcus jostii RHA1
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DOI：
10.1128/aem.02621-09
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发表时间：
2010-03-01
影响因子：
4.4
通讯作者：
Mohn, William W.
中科院分区：
文献类型：
--
作者：
Hara, Hirofumi;Stewart, Gordon R.;Mohn, William W.
邻苯二甲酸酯（PE）是重要的环境污染物。虽然母体化合物邻苯二甲酸酯（PTH）的生物降解性得到了很好的表征，但对PE的生物降解性还没有很好的了解。特别是，在这项研究之前，参与这些化合物的吸收和水解的基因没有最终确定。我们发现，Rhodococcus jostii RHA 1可以生长在各种单烷基PE，包括甲基，丁基，己基和2-乙基己基PTH。菌株RHA 1不能生长在大多数二烷基PE，但PTH转化二甲基，二乙基，二丙基，正己基，二-（2-乙基己基）PTH生长的细胞悬浮液。这些二烷基聚乙烯的主要产物是PTH和相应的单烷基聚乙烯，以及由烷基侧链缩短引起的次要产物。RHA 1表现出一个诱导型的，ATP依赖性的PTH摄取系统，Km为22 μ M。patB基因的缺失和互补表明，由patDABC编码的ATP结合盒（ABC）转运蛋白是RHA 1摄取PTH和单烷基PE所必需的。在大肠杆菌中表达了RHA 1的patE编码的水解酶。PatE特异性地将单烷基PE水解为PTH，但不转化二烷基PE或其它芳族酯。RHA 1的调查阐明了与PE的环境命运一致的关键过程。
Phthalate esters (PEs) are important environmental pollutants. While the biodegradation of the parent compound, phthalate (PTH), is well characterized, the biodegradation of PEs is not well understood. In particular, prior to this study, genes involved in the uptake and hydrolysis of these compounds were not conclusively identified. We found that Rhodococcus jostii RHA1 could grow on a variety of monoalkyl PEs, including methyl, butyl, hexyl, and 2-ethylhexyl PTHs. Strain RHA1 could not grow on most dialkyl PEs, but suspensions of cells grown on PTH transformed dimethyl, diethyl, dipropyl, dibutyl, dihexyl and di-(2-ethylhexyl) PTHs. The major products of these dialkyl PEs were PTH and the corresponding monoalkyl PEs, and minor products resulted from the shortening of the alkyl side chains. RHA1 exhibited an inducible, ATP-dependent uptake system for PTH with a K-m of 22 mu M. The deletion and complementation of the patB gene demonstrated that the ATP-binding cassette (ABC) transporter encoded by patDABC is required for the uptake of PTH and monoalkyl PEs by RHA1. The hydrolase encoded by patE of RHA1 was expressed in Escherichia coli. PatE specifically hydrolyzed monoalkyl PEs to PTH but did not transform dialkyl PEs or other aromatic esters. This investigation of RHA1 elucidates key processes that are consistent with the environmental fate of PEs.