The availability of a system for the functional expression of genes coding formolybdenumhydroxylases is a prerequisite for the construction of enzyme variants bymutagenesis. For the expression cloning of quinoline 2-oxidoreductase (Qor) fromPseudomonas putida86 – that contains the molybdo-pterin cytosine dinucleotide molybdenum cofactor (Mo-MCD), two distinct [2Fe)2S] clusters and FAD – the qorMSLgenes were inserted into the broad host range vector, pJB653, generating . putidaKT2440 and P. putida86-1Dqor were used as recipients for pUF1
