Two roles for the DNA recognition site of the Klebsiella aerogenes nitrogen assimilation control protein.
Two roles for the DNA recognition site of the Klebsiella aerogenes nitrogen assimilation control protein.
复制标题
产气克雷伯菌氮同化控制蛋白 DNA 识别位点的两个作用。
DOI：
10.1128/jb.180.3.578-585.1998
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发表时间：
1998
影响因子：
3.2
通讯作者：
Bender,RA
中科院分区：
文献类型：
--
作者：
Pomposiello,PJ;Janes,BK;Bender,RA
The nitrogen assimilation control protein (NAC) binds to a site within the promoter region of the histidine utilization operon (hutUH) ofKlebsiella aerogenes, and NAC bound at this site activates transcription ofhutUH. This NAC-binding site was characterized by a combination of random and directed DNA mutagenesis. Mutations that abolished or diminished in vivo transcriptional activation by NAC were found to lie within a 15-bp region contained within the 26-bp region protected by NAC from DNase I digestion. This 15-bp core has the palindromic ends ATA and TAT, and it matches the consensus for LysR family transcriptional regulators. Protein-binding experiments showed that transcriptional activation in vivo decreased with decreasing binding in vitro. In contrast to the NAC-binding site fromhutUH, the NAC-binding site from thegdhApromoter failed to activate transcription from a semisynthetic promoter, and this failure was not due to weak binding or greatly distorted protein-DNA structure. Mutations in the promoter-proximal half-site of the NAC-binding site fromgdhAallowed this site to activate transcription. Similar studies using the NAC-binding site fromhutshowed that two mutations in the promoter proximal half-site increased binding but abolished transcriptional activation. Interestingly, for symmetric mutations in the promoter-distal half-site, loss of transcriptional activation was always correlated with a decrease in binding. We conclude from these observations that if the binding in vitro reflects the binding in vivo, then binding of NAC to DNA is not sufficient for transcriptional activation and that the NAC-binding site can be functionally divided in two half-sites, with related but different functions.
