3-Ketosteroid 9 alpha-hydroxylase enzymes:Rieske non-heme monooxygenases essential for bacterial steroid degradation

Various micro-organisms are able to use sterols/steroids as carbon- and energy sources for growth. 3-Ketosteroid 9 alpha-hydroxylase (KSH), a two component Rieske non-heme monooxygenase comprised of the oxygenase KshA and the reductase KshB, is a key-enzyme in bacterial steroid degradation. It initiates opening of the steroid polycyclic ring structure. The enzyme has industrial relevance in the synthesis of pharmaceutical steroids. Deletion of KSH activity in sterol degrading bacteria results in blockage of steroid ring opening and is used to produce valuable C19-steroids such as 4-androstene-3,17-dione and 1,4-androstadiene-3,17-dione. Interestingly, KSH activity is essential for the pathogenicity of Mycobacterium tuberculosis. Detailed information about KSH thus is of medical relevance, and KSH inhibitory compounds may find application in combatting tuberculosis. In recent years, the 3D structure of the KshA protein of M. tuberculosis H37Rv has been elucidated and various studies report biochemical characteristics and possible physiological roles of KSH. The current knowledge is reviewed here and forms a solid basis for further studies on this highly interesting enzyme. Future work may result in the construction of KSH mutants capable of production of specific bioactive steroids. Furthermore, KSH provides an promising target for drugs against the pathogenic agent M. tuberculosis.</p

New expression system from rhodococcus

The present invention provides an isolated polynucleotide comprising the kstD promoter from Rhodococcus erythrypolis. The polynucleotide can very advantageously be used as a controllable transcription activator. Said controlling function can be provided by providing said isolated polynucleotide with a nucleotide sequence encoding a transcription regulator of said promoter. In the present invention, such a transcription regulator may be externally induced, such as by introduction of steroidal compounds. In an alternative embodiment of the present invention the isolated polynucleotide may comprise the kstR gene or a homologue or a functional part thereof as the transcription regulator of the kstD promoter

Pharmaceutical composition to protect an animal against a disorder arising from an infection with a bacterium that belongs to the group of nocardioform actinomycetes

The invention pertains to a pharmaceutical composition to protect an animal against a disorder arising from an infection with a bacterium that belongs to the group of nocardioform actinomycetes having the ability to survive within macrophages of the animal, comprising live bacteria of a nocardioform actinomycetes species, the live bacteria being attenuated by inactivation of a gene that encodes a protein involved in methylhexahydroindanedione propionate degradation, and a pharmaceutically acceptable carrier for these live bacteria.<br/