Cyclic AMP-dependent osmoregulation of crp gene expression in Escherichia coli
Cyclic AMP-dependent osmoregulation of crp gene expression in Escherichia coli
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DOI：
10.1128/jb.00235-06
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发表时间：
2006-08-01
影响因子：
3.2
通讯作者：
Uhlin, Bernt Eric
中科院分区：
文献类型：
--
作者：
Balsalobre, Carlos;Johansson, Jorgen;Uhlin, Bernt Eric
我们发现大肠杆菌中的环腺苷酸（cAMP）受体蛋白（CRP）-cAMP调节复合物在CRP基因表达水平上受到cAMP的调节。cya突变株的CRP调节功能丧失，但可通过外部添加cAMP恢复，表明细胞内cAMP水平是CRP的CRP调节的关键因素。细胞维持最佳CRP活性的能力对于低渗透压条件下细菌的生长和存活至关重要，如不同CRP突变等位基因的研究所示。CRP中具有新氨基酸取代（L124 R）的抑制突变体在低渗透压下显示恢复生长。CRP（L124 R）不被cAMP激活，并且显示出相对于野生型为显性阴性。我们的研究结果表明，微调的CRP活性可能是至关重要的细菌的生存能力和适应性不断变化的渗透条件。
We have found that the cyclic AMP (cAMP) receptor protein (CRP)-cAMP regulatory complex in Escherichia coli is subject to osmoregulation at the level of crp gene expression. This osmoregulation was lost in a cya mutant strain but could be restored by external addition of cAMP, suggesting that the intracellular level of cAMP is a key factor in the osmoregulation of CRP. The ability of the cell to maintain optimal CRP activity was essential for the growth and survival of the bacteria under low-osmolarity conditions as shown by studies with different crp mutant alleles. A suppressor mutant with a novel amino acid substitution (L124R) in CRP showed restored growth at low osmolarity. CRP(L124R) was not activated by cAMP and was shown to be dominant negative over the wild type. Our findings suggest that the fine-tuning of the CRP activity may be critical for bacterial viability and adaptability to changing osmotic conditions.