DeVault J D, Hendrickson W, Kato J, Chakrabarty A M
Department of Microbiology and Immunology (M/C 790), University of Illinois College of Medicine, Chicago 60612.
Mol Microbiol. 1991 Oct;5(10):2503-9. doi: 10.1111/j.1365-2958.1991.tb02096.x.
The environmentally activated algD promoter of Pseudomonas aeruginosa has been shown to be influenced by DNA supercoiling. It is believed that protein-induced bending or looping is required for this activation. We studied the role of Escherichia coli cAMP-CRP on algD promoter activation in E. coli and show that a functional CRP is required for this activation. We also demonstrate that the algD promoter is sensitive to glucose repression both in E. coli and P. aeruginosa. Deletion of a putative consensus CRP binding sequence upstream of the algD promoter renders the promoter non-responsive to glucose repression. The involvement of cAMP-CRP complex in the activation of the algD promoter in E. coli has been demonstrated directly through binding of a 255 base pair DNA fragment containing the putative consensus CRP binding sequence. Other fragments, upstream or downstream but without any consensus CRP binding sequence, did not show any binding with CRP. A CRP-like analogue, similar to that in Xanthomonas campestris, but capable of activating genes without forming a complex with cAMP, is believed to allow glucose repression in P. aeruginosa.
铜绿假单胞菌的环境激活型algD启动子已被证明受DNA超螺旋影响。据信这种激活需要蛋白质诱导的弯曲或成环。我们研究了大肠杆菌cAMP-CRP对algD启动子在大肠杆菌中的激活作用，并表明功能性CRP是这种激活所必需的。我们还证明algD启动子在大肠杆菌和铜绿假单胞菌中均对葡萄糖阻遏敏感。删除algD启动子上游一个假定的共有CRP结合序列会使启动子对葡萄糖阻遏无反应。通过包含假定共有CRP结合序列的255个碱基对DNA片段的结合，直接证明了cAMP-CRP复合物参与了algD启动子在大肠杆菌中的激活。其他片段，无论是上游还是下游片段，但没有任何共有CRP结合序列，均未显示与CRP有任何结合。一种类似于野油菜黄单胞菌中的CRP样类似物，但能够在不与cAMP形成复合物的情况下激活基因，据信它使得铜绿假单胞菌中存在葡萄糖阻遏。
