• What makes a plant expression vector different than bacterial expression vector?
A plant expression vector is specifically designed for use in plant cells, while a bacterial expression vector is designed for use in bacterial cells. The main differences between the two vectors stem from the unique characteristics and requirements of plant and bacterial cellular systems.
1. Origin of Replication: Plant expression vectors typically contain an origin of replication (ori) that is compatible with plant cells, allowing the vector to replicate within the plant cell's nucleus. Bacterial expression vectors, on the other hand, contain an ori that allows replication within bacterial cells.
2. Promoter: Plant expression vectors contain a promoter that can drive gene expression specifically in plant cells. Plant promoters are recognized and utilized by the plant's transcriptional machinery, ensuring proper gene expression levels. Bacterial expression vectors possess a promoter that enables efficient gene expression in bacterial cells by interacting with the bacterial transcriptional machinery.
3. Selection Markers: Plant expression vectors often incorporate selectable markers that allow for the identification and purification of plant cells that have successfully taken up the vector. These markers may confer resistance to specific antibiotics or confer the ability to synthesize certain compounds, making it easier to select and differentiate transformed plant cells. Bacterial expression vectors commonly incorporate markers, such as antibiotic resistance genes, which help in the selection of transformed bacterial cells.
4. Transcriptional Termination: Plant expression vectors contain transcriptional termination signals compatible with plant cells, ensuring the proper termination of transcription in plant cells. Bacterial expression vectors, on the other hand, contain termination signals that are recognized by the bacterial transcriptional machinery and facilitate the termination of transcription in bacterial cells.
5. Introns and Enhancers: Plant expression vectors may include introns, which are important for gene regulation and alternative splicing in plant cells. Enhancer elements may also be included to enhance gene expression in plants. Bacterial expression vectors typically lack introns and enhancer elements, as bacterial cells do not require them for gene expression.
To determine these differences, one could compare the sequences and features of commonly used plant expression vectors, such as pCAMBIA or pGreen, with those of well-known bacterial expression vectors like pET or pBAD. By examining the vector backbones and the specific elements mentioned above (e.g., origin of replication, promoters, selection markers, transcriptional termination signals, presence/absence of introns and enhancers), it becomes evident how these vectors are optimized for their respective host cells, plant or bacterial.