Cobalt-dependent transcription of the nitrile hydratase gene in Rhodococcus rhodochrous M8

Abstract The effects of cobalt ions on the activities of Rhodococcus rhodochrous M8 enzymes for nitrile utilization, nitrile hydratase and amidase, were investigated. In contrast to amidase, synthesis of nitrile hydratase and its activity required cobalt ions in the growth medium. Northern blot analysis showed that in the presence of cobalt ions, the level of mRNA for nitrile hydratase genes was several times higher than that under cobalt-limited conditions. It was assumed that the low nitrile hydratase activity in cells grown in the absence of cobalt ions is connected either with the weak expression of nitrile hydratase genes or with the rapid degradation of nitrile hydratase mRNA.