Abstract
As a part of the host cell development for a amplified recombinant trp operon, $aroP^-$ mutation was introduced in a E. coli host strain. $aroP^-$ mutation was induced by transposon Tn10 and transduced into the E. coli host cell by bacteriophage P1Kc. The effect of $aroP^-$ mutation on the excretion of tryptophan in E. coli $trpR^{-ts}/ColE_1 -trp^+$ cells was investigated. Mutant lacking the general aromatic transport system was resistant to ${\beta}-2-thienylalanine\;(2{\times}10^{-4}\;M)$, p-fluorophenylalanine $(2{\times}10^{-4}M)$, or 5-methyltryptophan $(2{\times}10^{-4}\;M.)[^3H]-tryptophan$ uptake of the $aroP^-$ mutant strain was reduced considerably as compared with $aroP^+$ counterpart. The rate of $[^3H]-tryptophan$ uptake of the $aroP^-$ mutant strain treated with $NaN_3(3{\times}10^{-2}\;M)$ was much less affected than that of $aroP^+$ counterpart. The $aroP^-$ transductants increased the tryptophan excretion from E. coli $trpR^{-ts}/ColE_1 -trp^+$ four times more than $aroP^+$ counterpart.
증폭된 재조합 trp operon의 발현을 위한 숙주박테리아 개발의 일환으로 숙수 E. coli에 $aroP^{-}$ 변이를 도입하였다. $aroP^{-}$ 변이의 유도에는 trans po son Tn10을 사용하였으며 P1Kc파아지를 이용하여 숙주박테리아에 형질도입하였다. General aromatic amino acid transport system이 결여된 $aroP^{-}$ 변이주는 $\beta$-thienylalanine ($(2{\times}10^{-4}M)$). p-fluor-phenylalanine ($(2{\times}10^{-4}M)$) 그리고 5-methyltryptophan에 저항성을 가졌다. $aroP^{-}$ 변이주는 $aroP^{-}$ 야생주에 비해서 〔$[^3H]$-tryptophan uptake가 상당히 감소하였다. 또한 NaN, ($(2{\times}10^{-4}M)$)를 처리하였을 때의 ($[^3H]$)-tryptophan uptake 비율은 aroP 변이주가 $aroP^{-}$야생주보다 덜 감소하였다. E. coli $trpR^{-ts}/ColE_1 -trp^+$ 균주에 aroP 형질을 도입하였을 때 트립토판 방출이 $aroP^{-}$ 야생주에 비해서 4 배나 증가하였다.