CAP is an allosteric activator of the lac operon. A second aspect of lac operon regulation is conferred by a trans-factor called cAMP binding protein (CAP, Figure \(\PageIndex{4}\)). CAP is another example of an allosterically regulated trans-factor.

原核生物中的乳糖操纵子（Lac operon）是一个经典的基因表达调控系统，通常存在于大肠杆菌（Escherichia coli）和其他细菌中。 乳糖操纵子用于控制乳糖的代谢，使细菌能够在需要时分解乳糖以获取能量。 笔记： 阻遏蛋白 是始终产生的，有乳糖时，这个乳糖相当于一把钥匙，插到阻遏蛋白上，使其从O位点脱离，促进转录，使得细菌能够利用乳糖。 无乳糖时，阻遏蛋白与O位点脱离结合，抑制转录，不合成代谢乳糖相关的酶，减少能量消耗。 同时，还受到葡萄糖的影 …

The lactose operon (lac operon) is an operon required for the transport and metabolism of lactose in E. coli and many other enteric bacteria. Although glucose is the preferred carbon source for most enteric bacteria, the lac operon allows for the effective digestion of lactose when glucose is not available through the activity of β ...

2024年10月18日 · Explore how glucose and cAMP levels intricately regulate the lac operon, influencing gene expression and metabolic pathways. Bacterial gene regulation is a fascinating aspect of molecular biology, with the lac operon serving as a classic example.

The lac operon is a well-known example of an inducible gene network that regulates the transport and metabolism of lactose in Escherichia coli. It encodes the genes for the internalization of extracellular lactose and then its conversion to glucose.

In the lactose operon of Escherichia coli, the final targets of glucose are the lac repressor and the positive regulator, the complex of cAMP receptor protein (CRP) and cAMP. First, glucose prevents the entry of inducer into the cell, resulting in an increase in the concentration of the inducer-free lac repressor.

It is believed that cAMP provides the positive regulating signal for the lac operon. At high levels (that indicate absence of glucose) cAMP binds a special protein (CAP, catabolite activator protein), and the CAP-cAMP complex in turn binds the CAP binding site of the lac promoter.

2022年9月2日 · Lac operon definition. The lactose or lac operon of Escherichia coli is a cluster of three structural genes encoding proteins involved in lactose metabolism and the sites on the DNA involved in the regulation of the operon.

2022年5月27日 · In this case, rather than blocking RNA polymerase, the activated cAMP-bound CAP induces even more efficient lac-operon transcription. The result is synthesis of higher levels of lac enzymes, which facilitate efficient cellular use of …

CAP-cAMP complex binding leads to enhanced RNA polymerase binding and activation of gene expression from the lac operon. Importantly, this process is affected by glucose levels, because...