|
KMID : 0545120030130040584
|
|
Journal of Microbiology and Biotechnology
2003 Volume.13 No. 4 p.584 ~ p.590
|
|
|
Enhanced Expression of β-Xylosidase of Bacillus stearothermophilus No. 236 by Change of Translational Initiation Codon in Escherichia coli and Bacillus subtilis
|
|
KIM, MI DONG
KIM, KYUNG-NAM/CHOI, YONG JIN
|
|
|
Abstract
|
|
|
|
The xylA gene of Bacillus sraurothemophilus No.236 encoding β-xylosidase, a major xylanolytic enzyme, was previously cloned and sequenced by the present authors. Sequence analysis indicated that translation of the xylA gene was initiated from the noncanonical initiation codon UUG, confirmed by analyzing three different amber (UAG) mutants of the xylA gene. In the present study, the UUG initiation codon was mutated into AUG or GUG, and the effects of the mutations on the XylA synthesis were examined. The AUG initiation codon was found to direct the highest level of β-xylosidase synthesis; three-fold and fourteen-fold more enzyme activity than the UUG codon in E. coli and B. subtilis cells, respectively. Surprisingly, contrary to other systems reported to date, the UUG start codon was found next to AUG in the relative order of translational efficiency in both organisms. In addition, a greater abundance of the xylA mRNA was detected with the AUG start codon in both of these host cells than with GUG or UUG. Northem blot and Toeprint assays revealed that this was due tn enhanced stability of mRNA with the AUG initiation codon. As expected, the P-xylosidase protein level in the bacterial cells containing mRNA with the AUG start codon was also much higher than the levels with the other two different mRNAs.
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
  
|
|