Regulation of a cold shock protein gene by cold, osmotic and heat stresses in Bifidobacterium breve KB 69

초록

The regulation of a cold shock protein (csp) gene expression in bifidobacterium breve KB 69 (AY172656) was investigatied at transcriptional and translational levels. First, a partial csp gene was cloned using degenerate primers which were designed based on the conserved regions of two csp domain amongst known csp genes. In Southern blot analysis we found the existence of multiple csp gene homolog in B. breve KB 69. The amount of csp mRNA was followed by using reverse trnascription-polymerase chain reaction (RT-PCR). First, the csp mRNA was more abundant in early-exponential phase than in other growth phases. The regulation of csp expression was examined under various stesses such as cold shock, salt stress and heat shock. The csp mRNA increased upon exposure to 5oC in early-exponential phase as well as under osmotic stress (0.4~0.6 M NaCl). However, the csp mRNA decreased under heat shock (42oC) condition. In addition when total proteins were analyzed by SDS-PAGE putative csp protein of ca. 7 kDa was found to appear in mid-exponential phase.