Name: how cis-regulatory dna controls transcription
Uploaded: 2020-11-23T11:47:37.000Z
Duration: 2 min 2 s
Channel: JoVE

转录调节剂 是与短时结合的蛋白质 具体的延伸 非编码DNA 被称为顺式调节 序列。这些基本组成部分 用于基因调控 存在 整个基因组。转录的 监管机构可以约束 顺式调控序列 双螺旋形式的DNA。DNA的螺旋形式有两个 大小不同的凹槽。较宽的凹槽，已知 作为主要的凹槽 比 较小的小凹槽 导致大多数 的互动 发生在主要凹槽处。的边缘 含氮碱 被暴露 凹槽和 能够氢键键合 和其它非共价 互动。此绑定 转录调节子 是序列特定的。但是，密切相关 序列也被识别。这个关联是 高度稳定的 由于多重非共价 涉及的互动。顺式调控序列 可以控制各个方面 基因转录，包括 抑制或引发 转录，以及 转录速率。它们可以广泛地 分为那些 紧邻 到转录位点 和那些成千上万的 碱基对的距离。那些是 关闭通常 促进者的一部分 序列 启动基因转录。那些较远的可以 参加增强 或使转录静音。通常，紧凑包装 DNA和染色体的关系 导致这些序列是 在空间上接近基因 它们监管，即使它们 在序列中距离较远。几种的组合 顺式调控序列 控制大多数 基因的表达。很少有基因会 在控制之下 只有一个单一序列。

<ol>
	<li>Alberts 等人，第 6 版;第 373-375 页</li>
	<li>巴卡利，M.（2011 年）。顺式调节元件的微进化:来自黑腹果蝇亚组中配对规则分割基因 fushi tarazu 的一个例子。公共科学图书馆一号，6（11）。</li>
</ol>

顺式调控元件

Cis-regulatory Sequences

顺式调控元件是非编码 DNA 的短片段，与它们所调控的基因存在于同一染色体上。 这些片段充当转录调节因子的结合位点，转录调节因子是负责控制真核生物中不同细胞类型的基因转录和差异基因表达的蛋白。 顺式调控元件可以靠近目标基因，也可以远离 DNA 序列数千个碱基； 然而，由于染色体中 DNA 的紧密包装，那些距离较远的序列通常在空间上位于它们所调节的基因附近。 序列中靠近的那些调节基因转录的起始，而那些远离的则增强或沉默基因转录。 几个顺式调控元件的作用对大多数基因进行转录调控； 然而，偶尔，也会出现单个顺式调控元件调节基因的转录。

当 DNA 呈双螺旋形式时，转录因子与顺式调控序列结合。 转录调节因子结合特定序列，但也能够结合密切相关的序列。 双螺旋有两种类型的凹槽：较小的小凹槽和较大的主凹槽。 由于主要 DNA 凹槽的大小，调节因子更有可能与它们结合。 转录调节剂通过含氮碱基对边缘存在的化学特征来识别特定的顺式调控元件。 例如，碱基具有沿着凹槽暴露的不同氢键供体和受体，可以与转录调控因子形成氢键。 由于这种结合还涉及许多非共价相互作用，因此这种结合非常稳定。

顺式调控序列是存在于与所调控基因相同染色体上的非编码DNA短片段。这些片段……

Education

教育

JoVE Core

Molecular Biology

分子生物学

Unit 1

第一单元

Gene Expression

基因表达

KEY TERMS AND CONCEPTS

关键术语与概念

how cis-regulatory dna controls transcription

Cis-regulatory sequences are short, non-coding DNA segments that control gene transcription. They sit on the same chromosome as the genes they regulate and act as binding sites for transcriptional regulators. In eukaryotes, these proteins help control gene expression patterns in different cell types.

These DNA sequences can be close to a gene or thousands of bases away. When they are far from the gene in the DNA sequence, they are often brought close together in space because chromosomes are tightly packed. Sequences near the gene usually help start transcription, while distant sequences can enhance or silence transcription.

Most genes are controlled by several cis-regulatory sequences. In some cases, only one cis-regulatory sequence regulates a gene. Transcription factors bind to these sequences when DNA is in its double-helix form.

Transcriptional regulators bind specific DNA sequences, but they can also bind closely related sequences. They often interact with the major groove of DNA because it is larger than the minor groove. Regulators recognize cis-regulatory sequences by chemical features at the edges of the base pairs, including hydrogen bond donors and acceptors. These interactions, along with other non-covalent forces, make the binding highly stable.

How Cis-Regulatory DNA Controls Transcription

how-cis-regulatory-dna-controls-transcription

cell specific gene expression

How Cells Switch Genes On and Off

Cells switch genes on and off to make different proteins for different jobs. In multicellular organisms, many cell types are built from the same DNA, but they do not use the same genes in the same way. This difference in gene expression helps explain why cells can look and act so differently. Liver cells are a clear example. They help detoxify blood, make bile to help digest fats, and produce proteins needed for metabolism. To do these jobs, liver cells must express a specific set of genes.

regulation of expression occurs at multiple steps

regulation-of-expression-occurs-at-multiple-steps

How Cells Control Gene Expression

Cells control gene expression at several points between DNA and protein. The most common control point is transcription. At this stage, proteins bind to short regulatory DNA sequences and can either increase or reduce transcription of the linked gene. After transcription, a precursor mRNA is made. This pre-mRNA contains exons, which code for protein, and introns, which do not. It must be processed before translation, and splicing removes the introns and joins the exons. Cells can also regulate...

cis-regulatory sequences

Cis-regulatory sequences are short, non-coding DNA segments that control gene transcription. They sit on the same chromosome as the genes they regulate and act as binding sites for transcriptional regulators. In eukaryotes, these proteins help control gene expression patterns in different cell types. These DNA sequences can be close to a gene or thousands of bases away. When they are far from the gene in the DNA sequence, they are often brought close together in space because chromosomes are...

cooperative binding of transcription regulators

cooperative-binding-of-transcription-regulators

How Transcription Factors Bind DNA

Transcriptional regulators bind to cis-regulatory DNA sequences to control gene transcription. These DNA sequences are very short, usually fewer than ten nucleotide pairs long. Because they are so short, the same sequence can appear by chance in many places across the genome. Some regulators can also bind to groups of similar sequences. That raises the chance of random binding even more. To lower this risk, transcription regulators often form dimers, which are pairs of proteins that bind a DNA...

prokaryotic transcriptional activators and repressors

prokaryotic-transcriptional-activators-and-repressors

Operon Control by Activators and Repressors

Operon control in prokaryotes depends on activators and repressors. Prokaryotic genes are often arranged in groups, not one by one like in eukaryotes. Genes that help carry out the same biochemical process are placed together with their regulatory elements. This group is called an operon, and it is transcribed into a single polycistronic mRNA strand. Activators and repressors are DNA-binding proteins that control transcription in an operon. Activators bind near the promoter, which is the site...

operons

Operons in Bacterial Gene Control

Operons help bacteria control groups of genes at the same time. An operon is a set of genes that are regulated together and can be turned on or off as a unit. This shared control helps bacteria respond quickly to changes in their environment. In many operons, a promoter gives RNA polymerase a place to bind and start transcription. The operon also includes a regulatory region that helps control whether the genes are expressed. When conditions change, the cell can use this setup to manage gene...

the eukaryotic promoter region

Eukaryotic Promoter Motifs and Gene Control

The eukaryotic promoter region is a stretch of DNA located upstream of a gene. It includes an RNA polymerase binding site, a transcription start site, and several cis-regulatory sequences. These DNA signals help control when transcription begins. The promoter can be divided into proximal and distal regions. The proximal promoter lies close to the gene and includes cis-regulatory sequences and the core promoter. The core promoter is the RNA polymerase binding site, and it is usually found...

co-activators and co-repressors

Chromatin Control in Gene Transcription

Chromatin control plays a major role in gene transcription in eukaryotes. Gene expression is regulated by several proteins that work together at a gene regulatory site. Some of these proteins bind directly to specific DNA sequences, while co-regulators attach to those regulators but do not bind DNA on their own. Co-regulators can act as co-activators or co-repressors, depending on the complex they join. One co-regulator may even switch roles in different settings. For example, the...

eukaryotic transcription activators

How Transcription Activators Turn Genes On

Transcription activators are proteins that help turn genes on by promoting transcription from DNA to RNA. They often have two parts. One part binds to DNA, and the other part activates transcription. In some proteins, such as the glucocorticoid receptor and MyoD, one domain can do both jobs. The DNA-binding part recognizes specific regulatory sequences on the DNA. These binding domains are grouped into families based on their structure. Common examples include the leucine zipper, zinc finger,...

eukaryotic transcription inhibitors

How Eukaryotic Gene Repressors Work

Eukaryotic gene repressors help turn specific genes off when the cell needs to control growth, development, or other biochemical processes. These DNA-binding proteins regulate gene expression in eukaryotes. Their presence at the right time and place can be triggered by hormones and signals from other cells. Most transcription inhibitors have two main parts. One part binds DNA, and the other is a repressor domain, which helps shut down transcription. Repressor domains can connect with basal...

combinatorial gene control

Gene Expression by Transcription Factor Combinations

Gene expression can depend on combinations of transcription factors working together. In combinatorial gene control, several transcription factors act in a coordinated way to regulate a single gene. If one or more of these factors are missing, the level of gene expression or repression can change a lot. This kind of control helps explain how a relatively small number of transcription factors can regulate a very large number of genes. More than 30,000 genes are controlled by about 2,000 to...

induced pluripotent stem cells

Reprogramming Cells into Stem Cells

Induced pluripotent stem cells are created by reprogramming mature cells back into a stem-cell state. This process shows that specialized cells can be changed into cells with broader developmental potential. The topic is important in biology because it links cell identity, gene control, and stem cell research. These cells begin as ordinary body cells and are pushed to de-differentiate, or lose their specialized features. After reprogramming, they behave like pluripotent stem cells, which means...

master transcription regulators

MEF2C and Gene Control Cascades

MEF2C is a master transcription regulator that controls gene expression in coordinated cascades. These regulators are proteins that manage the activity of multiple genes that often work together to produce a complex outcome. When a master transcription regulator is activated, it can start a chain of transcriptional activation that supports that outcome. Master transcription regulators can act in two main ways. They may bind directly to the regulatory sequences of several genes involved in a...

epigenetic regulation

DNA Methylation and Histone Changes

Epigenetic regulation controls gene activity without changing the DNA sequence. It helps determine when genes are turned on or off in a cell. Two major epigenetic mechanisms are DNA methylation and histone modification. DNA methylation adds chemical groups to DNA, while histone changes affect how tightly DNA is packed around histone proteins. These changes can make genes easier or harder to use. In high school biology, epigenetic regulation is important for understanding how cells with the...

genomic imprinting and inheritance

Genomic Imprinting in Human Disease

Genomic imprinting affects how some inherited genes are turned on or off in human cells. Diploid organisms inherit chromosomes from both parents, and each gene usually has two alleles. In most cases, both alleles are expressed. If one allele is missing or mutated, the other can often compensate, but some genes do not work that way. In genomic imprinting, a gene or its regulatory sequence carries chemical tags, such as methyl groups, on the copy inherited from only one parent. These tags are...

key terms and concepts

Learn how cis-regulatory DNA sequences bind transcription factors, control gene transcription, and help turn genes on or off in different cell types.

How Cis-Regulatory DNA Controls Transcription | JoVE K12

molecular biology

JoVE Core 分子生物学通过清晰简洁的动画视频课程展示了细胞的分子过程。此外，在科学家在行动的视频中，这些概念的应用是通过现代实验室中的真实实验演示的。

How Cis-Regulatory DNA Controls Transcription

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