What are the main factors affecting the expression efficiency of exogenous genes in the prokaryotic

The regulation of gene expression in eukaryotes is much more complex than in prokaryotes and can occur at a variety of different levels, such as DNA level, transcriptional level, post-transcriptional modification, translational level, and post-translational modification (possible regulatory links in eukaryotic gene expression). However, the most economical and major regulatory link is still at the transcriptional level.

Regulation at the DNA level controls gene expression by changing the number, structural sequence, and activity of relevant genes in the genome. Regulatory mechanisms in this category include amplification, rearrangement, or chemical modification of genes. Some of these changes are reversible.

Hello, it is a pleasure to serve you and give you the following answer: the regulation of gene expression in prokaryotes mainly occurs at the DNA level, that is, at the genomic level. The gene expression regulation mechanism of prokaryotes is mainly divided into two parts, one is the transcriptional regulation of genes, and the other part is the translational regulation of transcription product mRNA.

Gene transcriptional regulation refers to the regulation of the upstream region of the gene, which mainly includes two parts, one part is to regulate the DNA sequence itself, and the other part is to regulate the binding of transcription factors. The regulatory DNA sequence itself can be divided into two types, one is the non-coding DNA sequence with a specific function, and the other is the promoter sequence of the regulatory gene. The binding of regulatory transcription factors is mainly achieved by regulating the binding of transcription factors to DNA sequences, which is also the main mechanism of gene transcriptional regulation.

The translation regulation of mRNA refers to the regulation of mRNA of transcription products, including the regulation of mRNA translation, mRNA stability, and the stability of mRNA translation products. Regulation of mRNA translation can be achieved by regulating the structure of the transcription product mRNA and the binding of translation factors that regulate the transcription product mRNA. Regulating mRNA stability can be achieved by regulating the binding of mRNA translation factors and regulating mRNA degradation pathways.

The stability of translation products that regulate mRNA can be achieved by modulating the structure and function of proteins. The solutions and practical steps of gene expression regulation in prokaryotes are mainly as follows: (1) study the mechanism of gene transcription regulation, discover and analyze the promoter sequence of regulatory genes, and regulate the binding of transcription factors; and (2) study the translational regulator of mRNA.

The efficient expression of exogenous genes in E. coli is affected by many factors, among which the role of the SD sequence is to provide a ribosomal binding site.

For a cell, endogenous DNA is the sequence of its genome (DNA that is present in its own organisms), while exogenous DNA is the DNA of other species or cells that is genetically engineered, or it can be a piece of DNA synthesized artificially. Prepare for height.

Genes have two characteristics: one is the ability to faithfully replicate themselves in order to maintain the basic characteristics of carrying organisms; The second is that genes can be "mutated", and the vast majority of mutations will cause diseases, and the other small part are non-pathogenic mutations. Non-pathogenic mutations bring raw material to natural selection, allowing organisms to be selected from natural selection to select the most suitable individuals for nature.

Escherichia coli:

Escherichia coli (scientific name: Escherichia coli (T.)Escherich 1885)), Escherichia coli in the family Enterobacteriaceae.

Discovered by Escherich in 1885. Periscombellia are motile and sporous.

Escherichia coli is a gram-negative short bacillus, which can ferment a variety of sugars to produce acid and gas, and is a normal habitat in the intestines of humans and animals. Lives mainly in the large intestine. There are a small number of special types of E. coli that are quite virulent and can cause serious outbreaks once infected.

Imitation seepage scale.

The most important feature of the expression regulation of prokaryotic genes is the operon pattern, which is mainly at the transcription level, that is, the regulation of RNA synthesis, followed by the translation level. There are usually two ways: initiation regulation, i.e., promoter regulation; Termination regulation, i.e., attenuator regulation.

Regulatory mechanism of prokaryotic genome: through the compound regulation of negative and positive regulatory factors, the binding of repressor proteins to manipulated genes hinders the binding of RNApol and P to form open promoter complexes and prevents gene transcription; When the repressor protein dissociates from the operon gene, the RNA polymerase binds to the promoter, and the initiation gene is transcribed, transcription initiation regulation: factors control the expression of specific genes, different factors can compete to bind RNA polymerase, and the core enzyme of RNA polymerase recognizes the promoters of different genes with holoenzymes composed of different factors.

Lactose operon is the most typical mode of gene transcriptional regulation in prokaryotes, and the transcriptional regulation mechanism of lactose operon: compound regulation through positive and negative regulators. Inhibitory proteins bind to operon genes, preventing RNApol from binding to P to form an open promoter complex and preventing gene transcription. The binding of CAP to the CAP binding site promotes the binding of RNApol to P, resulting in efficient transcription.

Two conditions are required for gene transcription of lactose operon structure genes: a. repressor protein dissociates from manipulative genes b. CAP binds to CAP binding sites. (Transcriptional regulation of arabinose operon, transcriptional regulation of tryptophan operon) Regulation of transcriptional termination:

There are two main categories of transcriptional termination regulation in prokaryotes: factor-dependent and factor-independent termination regulation; Regulation of translation level: the influence of the order and position of the SD sequence on translation, the SD sequence is a nucleotide sequence composed of 3-9 bases upstream of the mRNA start codon AUG, which is the ribosomal binding site.

Prokaryotes. Gene expression regulation is present at every step of the initiation, extension, and termination of transcription and translation. This kind of regulation is mostly based on operons.

It is economical and effective to organize functionally related genes together and turn on or off gene expression at the same time to ensure the needs of their vital activities. Regulation mainly occurs at the transcriptional level, and there are two mechanisms, positive and negative, and the regulation of gene expression at the transcriptional level is determined by the structure of DNA, RNA polymerase.

function, protein factors, and other small molecule ligand interactions. The transcription and translation processes of bacteria are coupled to each other almost at the same time.

There are two ways for cells to control the expression levels of various proteins at different times: (1) cells control the speed at which their specific mRNA is transcribed from their DNA templates, which is an economical way to reduce the consumption of small molecule substances synthesized from mRNA, which is the result of natural selection during the long-term evolution of organisms, and this control is called transcriptional level regulation. (2) After mRNA synthesis, control the translation of peptide chains from mRNA.

Velocity, including processes such as the assembly speed of some enzymes and their complex molecule associations involved in translation. This control of protein synthesis and its gene expression is called translational-level regulation.