中等度好熱性細菌Geobacillus stearothermophilus生育温度変異株におけるタンパク質発現解析

Optimum growth of moderately thermophile Geobacillus stearothermophilus (Bst) has been observed at 55ºC, and suppressed by the downshift to lower temperature. In order to understand the relationship between growth temperature and protein expression, we made Bst mutant strains which were adapted to lower temperature (30ºC) compared with wild type strain, and then we examined their protein expression under various growth temperatures. When they were cultured at 55ºC, different expression patterns of six proteins (P1-P6) were observed between wild type and mutant strains, whereas five proteins (A1-A5) were found only in mutant strains cultured at 37ºC. Furthermore, expression of five proteins (DS1-DS5) was increased according to the downshift of growth temperature to 37ºC. Among all 16 proteins, abundant three proteins (P1, DS3, and DS5) were electroblotted to PVDF membrane, followed by analyzed N-terminal amino acid sequences. As a result, it was suggested that P1 must be Surface-layer protein A (sbsA), whereas DS3 and DS5 were unknown proteins.