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Isolation and characterization of Tn ‐Dha1, a transposon containing the tetrachloroethene reductive dehalogenase of Desulfitobacterium hafniense strain TCE1
Author(s) -
Maillard Julien,
Regeard Christophe,
Holliger Christof
Publication year - 2005
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2004.00671.x
Subject(s) - biology , transposable element , dehalogenase , genetics , gene , insertion sequence , gene cluster , transposase , operon , inverted repeat , inverse polymerase chain reaction , microbiology and biotechnology , polymerase chain reaction , mutant , genome , multiplex polymerase chain reaction
Summary A new 9.9 kb catabolic transposon, Tn ‐Dha1, containing the gene responsible for tetrachloroethene (PCE) reductive dechlorination activity, was isolated from Desulfitobacterium hafniense strain TCE1. Two fully identical copies of the insertion sequence IS Dha1, a new member of the IS 256 family, surround the gene cluster pceABCT , a truncated gene for another transposase and a short open reading frame with homology to a member of the twin‐arginine transport system ( tatA ). Evidence was obtained by Southern blot for an alternative form of the transposon element as a circular molecule containing only one copy of IS Dha1. This latter structure most probably represents a dead‐end product of the transposition of Tn ‐Dha1. Strong indications for the transposition activity of IS Dha1 were given by polymerase chain reaction (PCR) amplification and sequencing of the intervening sequence located between both inverted repeats (IR) of IS Dha1 (IR junction). A stable genomic IS Dha1 tandem was excluded by quantitative real‐time PCR. Promoter mapping of the pceA gene, encoding the reductive dehalogenase, revealed the presence of a strong promoter partially encoded in the right inverted repeat of IS Dha1. A sequence comparison with pce gene clusters from Desulfitobacterium sp. strains PCE‐S and Y51 and from Dehalobacter restrictus , all of which show 100% identity for the pceAB genes, indicated that both Desulfitobacterium strains seem to possess the same transposon structure, whereas only the pceABCT gene cluster is conserved in D. restrictus .