Effects of the Pup-proteasome system on the growth of Mycobacterium smegmatis strains

Objective To study the effects of prokaryotic ubiquitin-like protein (Pup)-proteasome system on the growth of Mycobacterium strains. Methods The genes encoding Pup (pup gene) and proteasome β subunit (prcB gene) were respectively knocked out from Mycobacterium smegmatis (M.sm) strains by homologous recombination. The growth and viability of the wild-type and mutant strains of M. sm were analyzed under normal culture condition and under hypoxia as well as anaerobic conditions. Results The pup and prcB genes were completely and precisely knocked out from M. sm strains and the mutant strains were named △SM-Pup and△SM-prcB, respectively. The △SM-Pup strains grew faster than the wild type (WT) and △SM-prcB strains. No significantly differences in the growth of M. sm were found between the WT and △SM-prcB strains. Conclusion The Pup-proteasome system was involved in the growth of M. sm, especially the pup gene. There was difference between pup and prcB genes in regulating the growth of M. sm. The functions and influences of Pup-proteasome system still need further investigation. Key words: Mycobacterium; Gene knockout; Prokaryotic ubiquitin-like protein; Proteasome; Viability