Effect of mutations in the cyclic AMP receptor protein-binding site on araBAD and araC expression.
Effect of mutations in the cyclic AMP receptor protein-binding site on araBAD and araC expression.
复制标题
环 AMP 受体蛋白结合位点突变对 araBAD 和 araC 表达的影响。
DOI：
10.1128/jb.171.2.1178-1184.1989
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发表时间：
1989
影响因子：
3.2
通讯作者：
Wilcox,G
中科院分区：
文献类型：
--
作者：
Stoltzfus,L;Wilcox,G
相邻但不同转录的araBAD操纵子和araC基因的最大表达需要环AMP（cAMP）和cAMP受体蛋白（CRP）的存在。DNA酶I保护研究先前已经揭示了在ara调节区中的高亲和力CRP结合位点。引入该位点的缺失突变导致araBAD和araC的表达减少。然而，其他实验已经证明，由于DNA环的破坏，ara调控区的间距变化可能具有多种影响。因此，缺失可能破坏了CRP结合位点，形成环的能力，或两者兼而有之。在本研究中，将置换突变引入CRP位点以避免产生间隔变化。我们发现，3个碱基对取代导致araBAD表达减少30%，而6个碱基对取代导致减少80%。这两个取代突变减少araC表达的三倍。我们得出结论，CRP结合到这个网站调节表达在两个方向。我们发现，CRP位点的间距变化不会改变araBAD的表达比取代突变。
Maximum expression of the adjacent but divergently transcribed araBAD operon and araC gene requires the presence of cyclic AMP (cAMP) and the cAMP receptor protein (CRP). DNase I protection studies have previously revealed a high-affinity CRP-binding site in the ara regulatory region. Deletion mutations introduced into this site resulted in reduced expression of araBAD and araC. However, other experiments have demonstrated that spacing changes in the ara regulatory region may have multiple effects due to disruption of a DNA loop. Thus, the deletions could have destroyed the CRP-binding site, the ability to form a loop, or both. In the present study, substitution mutations were introduced into the CRP site in order to avoid creating spacing changes. We found that a 3-base-pair substitution resulted in a 30% reduction in araBAD expression, whereas a 6-base-pair substitution resulted in an 80% reduction. Both of these substitution mutations reduced araC expression threefold. We conclude that CRP bound to this site regulates expression in both directions. We found that a spacing change in the CRP site does not alter araBAD expression any more than does a substitution mutation.