Differentiation of carbazole catabolic operons by replacement of the regulated promoter via transposition of an insertion sequence
Differentiation of carbazole catabolic operons by replacement of the regulated promoter via transposition of an insertion sequence
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DOI：
10.1074/jbc.m600234200
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发表时间：
2006-03-31
影响因子：
4.8
通讯作者：
Nojiri, H
中科院分区：
文献类型：
--
作者：
Miyakoshi, M;Urata, M;Nojiri, H
The carbazole catabolic car operons from Pseudomonas resinovorans CA10 and Janthinobacterium sp. J3 have nearly identical nucleotide sequences in their structural and intergenic regions but not in their flanking regions. Transposition of ISPre1 from the anthranilate catabolic ant operon located an inducible promoter P-ant upstream of the car(CA10) operon, which is regulated by the AraC/ XylS family activator AntR in response to anthranilate. The transposed P-ant drives transcription of the car(CA10) operon, which is composed of the carAaAaBaBbCAcAdDFE(CA10) structural genes. Transcriptional fusion truncating P-ant upstream of carAa(CA10) resulted in constitutive luciferase expression. Primer extension analysis identified a transcription start point of the constitutive mRNA of the car(CA10) operon at 385 nucleotides upstream of the carAa(CA10) translation start point, and the P-carAa promoter was found. On the other hand, a GntR family regulatory gene carR(J3) is divergently located upstream of the car(J3) operon. The P-u13 promoter, required for inducible transcription of the car(J3) operon in the presence of carbazole, was identified in the region upstream of carAa(J3), which had been replaced with the P-ant promoter in the car(CA10) operon. Deletion of carR(J3) from a transcriptional fusion resulted in high level constitutive expression from P-u13. Purified CarR(J3) protein bound at two operator sequences O-I and O-II, showing that CarR(J3) directly represses P-u13 in the absence of its inducer, which was identified as 2- hydroxy- 6- oxo- 6-( 2'- aminophenyl) hexa- 2,4- dienoate, an intermediate of the carbazole degradation pathway.
