Emergence of two types of nondechlorinating variants in the tetrachloroethene-halorespiring Desulfitobacterium sp strain Y51
Emergence of two types of nondechlorinating variants in the tetrachloroethene-halorespiring Desulfitobacterium sp strain Y51
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DOI：
10.1007/s00253-005-0112-9
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发表时间：
2006-05-01
影响因子：
5
通讯作者：
Furukawa, Kensuke
中科院分区：
文献类型：
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作者：
Futagami, Taiki;Tsuboi, Yoshinori;Furukawa, Kensuke
脱硫杆菌Y51菌株对四氯乙烯（PCE）表现出很强的脱氯活性，通过PceA还原脱卤酶（由pceA编码）的作用将PCE经由三氯乙烯转化为顺式-1，2-二氯乙烯。pceA基因簇周围的基因组织被确定为以下顺序：orf 4、orf 3、ISDesp 1、pceA-B-C-T-mcpA和ISDesp 2，其中pceA基因簇被ISDesp插入序列的两个几乎相同的拷贝包围。连续传代培养的菌株Y51产生的变体，废除PCE脱氯活性。Southern杂交分析显示两种类型的变异称为小缺失（SD）和大缺失（LD）。两种变体的表征揭示了围绕pceAB基因簇的遗传重排。在变体SD中，缺失了由1，572 bp组成的ISDesp 1，其包括编码IS 256家族转座酶的tnpAa和未知orf 1。ISDesp 1含有反向末端重复序列和pceA基因上游的-35启动子延伸，表明该IS元件参与了变体SD的形成。pceA转录的损失改变了变体SD的PCE-非脱氯表型。变体LD丢失了6.5-kb区域，包括ISDesp和pceABCT-mcpA基因簇的一个拷贝，证实同源重组与该变体的出现相关。
Desulfitobacterium sp. strain Y51 exhibits a strong dechlorinating activity for tetrachloroethene (PCE), converting it to cis-1,2-dichloroethene via trichloroethene by the action of the PceA reductive dehalogenase (encoded by pceA). The gene organization around the pceA gene cluster was determined to be in the following order: orf4, orf3, ISDesp1, pceA-B-C-T-mcpA, and ISDesp2, where the pceA gene cluster is surrounded by two nearly identical copies of the ISDesp insertion sequence. Serial subculture of strain Y51 gave rise to variants that abolished the PCE-dechlorination activity. Southern hybridization analysis revealed two types of variants termed small deletion (SD) and large deletion (LD). The characterization of both variants revealed a genetic rearrangement around the pceAB gene cluster. In variant SD, ISDesp1 comprised of 1,572 bp was deleted, which includes the tnpAa encoding IS256 family transposase and unknown orf1. The ISDesp1 contained the inverted terminal repeat sequence and a -35 promoter stretch just upstream of the pceA gene, indicating that this IS element is involved in the formation of the variant SD. Loss of the pceA transcription changed the variant SD to the PCE-nondechlorinating phenotype. The variant LD lost the 6.5-kb region, including one copy of ISDesp and the pceABCT-mcpA gene cluster, confirming that the homologous recombination is associated with the emergence of this variant.