Note that Ralstonia eutropha was formerly named Alcaligenes eutrophus. ISJp4 is located within (hence inactivating) the tfdT (lysR-type transcriptional regulator) gene, downstream of tfdK (a putative transport protein gene), tfdBII (chlorophenol monooxygenase), tfdFII (maleylacetate reductase) and other genes involved in the chlorocatechol degradation pathway. Based on comparison with other elements from the IS5 family, the limits of ISJp4 have been redefined, removing the first and last bp. Although ISJp4 displays two ORFs, a fused ORF is considered here (89-442) and (439-906). However, at position 437, the sequence 5'-CAAAAACTGGTCC-3' is reminiscent of what is found in other related elements, such as IS402 (The same observation has also been made by Leveau and van der Meer, 1997). The involvement of a putative -1 translational frameshift around position 437 remains to be confirmed. ISJp4 and IS402 transposases are 81 % identical. ISJp4 is present as a single copy on the pJP4 plasmid and as a single copy in the Ralstonia eutropha JMP134 chromosome.