COORDINATED REGULATION OF AMINO SUGAR BIOSYNTHESIS AND DEGRADATION - THE NAGC REPRESSOR ACTS AS BOTH AN ACTIVATOR AND A REPRESSOR FOR THE TRANSCRIPTION OF THE GLMUS OPERON AND REQUIRES 2 SEPARATED NAGC BINDING-SITES
COORDINATED REGULATION OF AMINO SUGAR BIOSYNTHESIS AND DEGRADATION - THE NAGC REPRESSOR ACTS AS BOTH AN ACTIVATOR AND A REPRESSOR FOR THE TRANSCRIPTION OF THE GLMUS OPERON AND REQUIRES 2 SEPARATED NAGC BINDING-SITES
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DOI：
10.1002/j.1460-2075.1995.tb00067.x
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发表时间：
1995-08-15
期刊：
影响因子：
11.4
通讯作者：
PLUMBRIDGE, J
中科院分区：
文献类型：
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作者：
PLUMBRIDGE, J
NAGC抑制子控制差异转录的NAGE-nagBACD操纵子的表达，这些操纵子参与氨基糖的摄取和降解，N-乙酰-D-氨基葡萄糖(GlcNAc)和氨基葡萄糖(GlcN)。GlmUS操纵子编码合成GlcN(GLMS)和形成UDP-GlcNAc(GlmU)所需的蛋白质，由位于glmU上游的两个启动子转录而成。在没有氨基糖的情况下，两个启动子都是活性的，但在GlcNAc的存在下，GlmU近端的启动子P1是无效的，而上游的启动子P2受到弱诱导，NAGC抑制子的两个结合部位分别位于P1上游的-200和-47bp。阻止NAGC与这两个位点中的任何一个结合的突变会消除P1启动子的表达，这表明NAGC的结合是glmU P1启动子表达所必需的，这意味着NAGC正在发挥该启动子的激活作用，此外，NAGC远端的位置表明该位点的行为类似于上游激活序列(UAS)。
The NagC repressor controls the expression of the divergently transcribed nagE-nagBACD operons involved in the uptake and degradation of the amino sugars, N-acetyl-D-glucosamine (GlcNAc) and glucosamine (GlcN). The glmUS operon, encoding proteins necessary for the synthesis of GlcN (glmS) and the formation of UDP-GlcNAc (glmU), is transcribed from two promoters located upstream of glmU. In the absence of amino sugars both promoters are active, However, in the presence of GlcNAc, the glmU proximal promoter, P1, is inactive while the upstream promoter, P2, is subject to weak induction, Two binding sites for the NagC repressor are located at -200 and -47 bp upstream of P1. Mutations which prevent NagC binding to either of these sites eliminate expression from the P1 promoter, This shows that binding of NagC is necessary for expression of the glmU P1 promoter and implies that NagC is playing the role of activator for this promoter, Moreover, the location of the distal NagC site suggests that this site is behaving like an upstream activating sequence (UAS).