The key difference between shuttle vector and expression vector is that shuttle vector is usually a plasmid that is not designed for gene expression studies in cells, while expression vector is usually a plasmid or virus that is designed for gene expression studies in cells.
In molecular biology, a vector is a DNA molecule used as a vehicle to carry foreign genetic material into another cell, where it can be replicated or expressed. The foreign genetic material contacting vector is generally called a recombinant DNA molecule. The four major types of vectors are plasmids, viral vectors, cosmids, and artificial chromosomes. Among these, the most commonly used vectors are plasmids. Shuttle vector and expression vector are two types of vectors used in molecular biology.
CONTENTS
1. Overview and Key Difference
2. What is a Shuttle Vector
3. What is an Expression Vector
4. Similarities – Shuttle Vector and Expression Vector
5. Shuttle Vector vs Expression Vector in Tabular Form
6. Summary – Shuttle Vector vs Expression Vector
What is a Shuttle Vector?
A shuttle vector is a vector designed to propagate in two different host species. Therefore, foreign DNA inserted into a shuttle vector can be tested or manipulated in two different cell types. Normally, a shuttle vector has two origins of replications, each of which is specific to a host. As shuttle vectors replicate in two different hosts, they are also known as bifunctional vectors. One popular shuttle vector is the yeast shuttle vector. Moreover, almost all the commonly used Saccharomyces cerevisiae vectors are shuttle vectors. For example, the yeast shuttle vector contains components that allow replication and selection in both yeast cells as well as E. coli cells. The E.coli components of the yeast shuttle vector are an origin of replication and a selectable marker (e.g., antibiotic resistance, beta-lactamase). The yeast components of the yeast shuttle vector are autonomously replicating sequence (ARS), a yeast centromere (CEN), and a selectable yeast marker (e.g., URA3- a gene that encodes an enzyme for uracil synthesis)
What is an Expression Vector?
An expression vector is usually a plasmid or virus constructed for gene expression in cells. This vector is used to introduce a specific gene into a target cell. This vector can take control of the cell’s mechanism for protein synthesis to produce the protein encoded by the specific gene. Once an expression vector is inside the cell, the protein that is encoded by the foreign gene is produced by using cellular translational machinery ribosome complexes.
Figure 01: Expression Vector
The expression vector is engineered to contain regulatory sequences that act as enhancer and promoter regions, which lead to the efficient transcription of the foreign gene. Hence, a significant amount of stable messenger RNA (mRNA) can later be translated into specific proteins. The expression of a protein by using an expression vector may be tightly controlled. The protein is produced in significant amounts when necessary through the use of an inducer. However, in some systems, the protein may be constitutively expressed. A popular example for expression vector is the pCI mammalian vector.
What are the Similarities Between Shuttle Vector and Expression Vector?
- Shuttle vector and expression vector are two types of vectors used in molecular biology.
- Both types of vectors can be plasmids.
- These types of vectors have an origin of replication.
- Both types of vectors have cloning sites.
- These vectors have selectable markers (antibiotic resistance).
What is the Difference Between Shuttle Vector and Expression Vector?
A shuttle vector is usually a plasmid that is not designed for gene expression studies in cells, while an expression vector is usually a plasmid or virus that is designed for gene expression studies in cells. Thus, this is the key difference between shuttle vector and expression vector. Furthermore, a shuttle vector does not need regulatory sequences such as strong promoter, enhancer, inducer, and portable translation initiation sequence (PTIS) and strong terminator. On the other hand, expression vector needs regulatory sequences such as strong promoter, enhancer, inducer and portable translation initiation sequence (PTIS), and strong terminator.
The below infographic presents the differences between shuttle vector and expression vector in tabular form for side by side comparison.
Summary – Shuttle Vector vs Expression Vector
Shuttle vector and expression vector are two types of vectors used in molecular biological experiments. A shuttle vector is usually a plasmid that is not designed for gene expression studies in cells, while an expression vector is usually a plasmid or virus that is designed for gene expression studies in cells. So, this is the key difference between shuttle vector and expression vector.
Reference:
1. “Shuttle Vector.” An Overview | ScienceDirect Topics.
2. “Expression Vector.” An Overview | ScienceDirect Topics.
Image Courtesy:
1. “PGEX-3X cloning vector” By Magnus Manske – Created by Magnus Manske. (CC BY-SA 3.0) via Commons Wikimedia