Bacterial plasmid DNA (pDNA) is typically a small (80 kb on average) circular extrachromososomal DNA element that persistently and stably exists outside the chromosome in a free form, capable of semi-autonomous replication by recruiting host cell mechanisms, and can carry genes that help the host adapt to a new environment or genes that encode specific functions.Get to know plasmids
Plasmids are smaller, non-cellular chromosome or nuclear DNA molecules attached to a cell that are capable of replicating autonomously (i.e., cell epiplasmids, cell epizosomes). Although most plasmids are in a circular configuration, they are found in many bacteria and yeasts, as well as in organelles such as chloroplasts and mitochondria in plants. However, in 1984, nemaline plasmids were discovered in actinomyces such as Streptomyces coelicoler and in prokaryotes such as Borrelia hermsii.Bailun protein and plasmid production process equipment
DNA lengths of native plasmids range from thousands of base pairs to hundreds of thousands of base pairs. Plasmids are naturally present in these organisms, and sometimes one or even several plasmids can exist in a cell at the same time. The number of copies of plasmids can range from single to thousands in a cell. Sometimes some plasmids contain a certain resistance gene (e.g., Escherichia coli contains a plasmid that contains an anti-tetracycline gene). Some plasmids carry genes that can give cells additional physiological and metabolic abilities, and even improve their pathogenicity in some bacteria. In general, the presence or absence of plasmids does not play a decisive role in host cell survival. It is the most common carrier for genetic engineering.Classification of plasmids- According to whether the plasmid can pass the interaction of bacteria, it can be divided into conjugative plasmids and non-conjugative plasmids.
- According to the type of replication of plasmids in bacteria, they can be divided into tight control type and relaxation control type.
- According to the incompatibility of plasmids, they can be divided into incompatibility and compatibility.
- According to the genes and characteristics of the host cells, they can be divided into the following six different types
They carry resistance genes that make the host bacteria resistant to certain antimicrobials, such as benzyl aminopenicillin, chloramphenicol, etc. Different bacteria can also contain the same resistant plasmid, such as the RP4 plasmid, which is present in Pseudomonas and other bacteria. R plasmids can also be transmitted in different species of bacteria in the form of infection.Genetic material can be passed between donor and recipient through conjugation. About 1/3 of the DNA of factor F constitutes an operon that transfers DNA, and about 35 genes are responsible for the synthesis and assembly of umbrella hairs. This is the region of DNA transfer and is positively regulated by the traJ gene product. It also has a reorganization area and a replication area. The recombination region contains multiple insertion sequences through which homologous recombination is performed. There are two replication initiation points in the replication region: one is OriV, which is used by the F-factor for autonomous replication in the host; The other is OriT, which is the starting point for rolling ring replication at the time of bonding.Carries a gene encoding colicin. Escherichia coli kills other bacteria.This plasmid encodes a special protein that allows the host bacteria to metabolize specialized molecules, such as toluene or salicylic acid.These plasmids give the host bacteria the ability to cause disease. For example, the Ti plasmid, which was found in Agrobacterium tumefaciens and is now processed as a common vector for plant transgenesis.It does not show any manifestation type and is mainly discovered by physical methods. (e.g. yeast 2 μm plasmid)Advantages of plasmids in the field of gene therapy
(1) In the process of gene transfer, plasmid vectors have low toxicity and low immunogenicity, can tolerate nucleases, and the transfer efficiency is independent of the size of genetic material;(2) In gene editing, plasmids can be used as editing tools for CRISPR/Cas9 system expression vectors and donors of gene repair sequences.
About BaiLun Biotechnology Co., Ltd
BaiLun Bio is a supplier and technical service provider of whole-set bioreactors (fermenter) and control systems. Our products include bioreactors (fermenter), animal cell bioreactors, bioreactor shakers, biological shakers, bottle rockers, control systems for bioreactors, etc. We can produce bioreactors with different volumes of 0.1L-1000KL and make our contributions for China′s bioreactor business to thrive throughout the world.
BaiLun has a contingent of engineers who have rich experience in fermenting processes, biochemical equipment and chemical technology. In addition, we also invite many nationally famous experts and scholars to act as our technical consultants, so as to ensure that our products have strong and steady technological foundations. The innovation of products and the technology leadership are the core parts of our products. Ensuring customer satisfaction is our permanent pursuit. Taking customer benefit as our own responsibility is the core value of Bailun Company.
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