Gene expression from plasmids containing the araBAD promoter at subsaturating inducer concentrations represents mixed populations
Gene expression from plasmids containing the araBAD promoter at subsaturating inducer concentrations represents mixed populations
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DOI：
10.1073/pnas.94.15.8168
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发表时间：
1997-07-22
影响因子：
11.1
通讯作者：
Hu, JC
中科院分区：
文献类型：
--
作者：
Siegele, DA;Hu, JC
来自含有araBAD启动子的质粒的基因表达可以通过生长培养基中阿拉伯糖的浓度来调节，Guzman等人[Guzman，L.- M.，贝林，D.，卡森，M. J，& Beckwith，J，（1995）J，Bacteriol. 177，4121-4130]表明，在亚饱和浓度的阿拉伯糖存在下生长的培养物中，克隆基因的表达可以被调节几个数量级，我们构建了从araBAD启动子表达快速折叠突变体维多利亚水母绿色荧光蛋白的质粒，以检查表达的基因产物在中等诱导水平下在单个细胞中的分布，在低阿拉伯糖浓度下生长的细胞的显微镜检查显示明亮荧光和暗细胞的混合物，表明培养物中的中间表达水平反映了诱导和未诱导细胞的群体平均值。绿色荧光蛋白诱导的动力学表明，这反映了由于诱导物通过主动转运的积累而引起的“自催化"诱导机制，这种机制类似于lacY（+）细胞中在亚饱和诱导剂浓度下对lac操纵子的诱导，40年前由Novick和Weiner描述[Novick，A，& Weiner，M.等人（1957）Proc. Natl，Acad，Sci. USA 43，553-566]。
Gene expression from plasmids containing the araBAD promoter can be regulated by the concentration of arabinose in the growth medium, Guzman et al. [Guzman, L.-M., Belin, D., Carson, M. J, & Beckwith, J, (1995) J, Bacteriol. 177, 4121-4130] showed that expression of a cloned gene could be modulated over several orders of magnitude in cultures grown in the presence of subsaturating concentrations of arabinose, we constructed plasmids expressing a fast-folding mutant Aequorea victoria green fluorescent protein from the araBAD promoter to examine the distribution of expressed gene Products in individual cells at intermediate induction levels, Microscopic examination of cells grown at low arabinose concentrations shows mixtures of brightly fluorescent and dark cells, suggesting that intermediate expression levels in cultures reflect a population average of induced and uninduced cells, The kinetics of green fluorescent protein induction suggest that this reflects an ''autocatalytic'' induction mechanism due to accumulation of the inducer by active transport, This mechanism, which is analogous to the induction of the lac operon at subsaturating inducer concentrations in lacY(+) cells, was described 40 years ago by Novick and Weiner [Novick, A, & Weiner, M. (1957) Proc. Natl, Acad, Sci. USA 43, 553-566].