Folding of the lysine riboswitch: importance of peripheral elements for transcriptional regulation
Folding of the lysine riboswitch: importance of peripheral elements for transcriptional regulation
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DOI：
10.1093/nar/gkq1247
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发表时间：
2011-04-01
影响因子：
14.9
通讯作者：
Lafontaine, Daniel A.
中科院分区：
文献类型：
--
作者：
Blouin, Simon;Chinnappan, Raja;Lafontaine, Daniel A.
枯草芽孢杆菌lysC赖氨酸核糖开关在赖氨酸结合时通过转录衰减机制调节自身基因表达。核糖开关适体围绕一个单一的五路连接点组织，该连接点为两个长程三级相互作用（环L2 - 环L3和螺旋P2 - 环L4）提供支架——所有这些都是为了创建一个特定的赖氨酸结合位点。我们已经确定，P2 - L4相互作用对于配体结合位点的组织以及核糖开关转录衰减控制尤为重要。此外，我们观察到L2 - L3和P2 - L4之间的折叠协同作用使得这两种相互作用在较低的镁离子浓度下就能折叠。P2 - L4相互作用对于涉及茎P1和P5的紧密并列也至关重要。赖氨酸的存在促进了这一过程，表明配体在折叠转变中具有积极作用。我们还表明，位于表达平台中一个先前未被表征的茎 - 环对核糖开关活性非常重要。因此，位于适体和表达平台中的折叠元件都会影响赖氨酸核糖开关的基因调控。
The Bacillus subtilis lysC lysine riboswitch modulates its own gene expression upon lysine binding through a transcription attenuation mechanism. The riboswitch aptamer is organized around a single five-way junction that provides the scaffold for two long-range tertiary interactions (loop L2-loop L3 and helix P2-loop L4)-all of this for the creation of a specific lysine binding site. We have determined that the interaction P2-L4 is particularly important for the organization of the ligand-binding site and for the riboswitch transcription attenuation control. Moreover, we have observed that a folding synergy between L2-L3 and P2-L4 allows both interactions to fold at lower magnesium ion concentrations. The P2-L4 interaction is also critical for the close juxtaposition involving stems P1 and P5. This is facilitated by the presence of lysine, suggesting an active role of the ligand in the folding transition. We also show that a previously uncharacterized stem-loop located in the expression platform is highly important for the riboswitch activity. Thus, folding elements located in the aptamer and the expression platform both influence the lysine riboswitch gene regulation.