Structure of the Regulatory Region of Nitrile Hydratase Genes in Rhodococcus rhodochrous М8, a Biocatalyst for Production of Acrylic Heteropolymers

Abstract—

Rhodococcus rhodochrous strain М8 is a platform for development of the biotechnologies for biocatalytic production of acrylic monomers, the raw material for synthesis of acrylic heteropolymers. A genetic system for investigation of the cobalt-dependent transcription of nitrile hydratase genes in this strain was constructed, based on the reporter gene of the metal-independent acylamidase from Rhodococcus qingshengii TA37. The cobalt-regulated promoter was shown to be located at a significant distance (~0.5 kb) from nitrile hydratase genes. Excision of the region between the promoter and the nitrile hydratase genes decreased significantly both the promoter activity and the degree of regulation by cobalt. Our results improve the possibilities for rational design of regulated expression cassettes using the promoter of nitrile hydratase genes in Rhodococcus, and for further development of biocatalysts based on these bacteria.