The gene encoding mycobacterial DNA-binding protein I (MDPI) transformed rapidly growing bacteria to slowly growing bacteria.

Pathogenic species of Mycobacterium are slowly growing intracellular bacteria. Slow growth is important for the parasitism of these organisms and chronicity of the disease, but its precise mechanism has not been elucidated. Recently, we found that a novel DNA-binding protein (MDPI) was expressed (7-10% in total protein) in mycobacteria, such as Mycobacterium bovis bacillus Calmette-Guérin, Mycobacterium tuberculosis, and Mycobacterium leprae. In this study, we observed that MDPI interfered with replication, transcription, and translation in the analysis in in vitro E. coli cell-free macromolecular biosynthesizing systems. Furthermore, MDPI inhibited the rapid growth of both Escherichia coli and Mycobacterium smegmatis, and NH(2)-terminal second amino acid, asparagine, was observed to be important in terms of this function. These data suggest an important role of MDPI for suppression of growth rates of mycobacteria.

Inhibition of multiplication of Mycobacterium leprae in mouse foot pads by immunization with ribosomal fraction and culture filtrate from Mycobacterium bovis BCG.

Immunization of mice with the ribosomal fraction from ruptured Mycobacterium bovis Bacillus Calmette-Guérin (BCG) and the culture filtrate reduced remarkably the multiplication of Mycobacterium leprae in the foot pads of mice. This is the first reported case of the protective activity against M. leprae multiplication in mice of the BCG ribosomal fraction and culture filtrate. The inhibition was more evident with the culture filtrate than with the ribosomal fraction. When the ribosomal proteins separated from ribosomal RNA were injected into mice, only slight inhibition was observed. Ribosomal RNA alone did not inhibit at all, in contrast to the conclusion reported by Youmans and Youmans.