Question

Mention the important features that were incorporated in each of the following vectors:
(i) COSMIDS
(ii) Shuttle Vectors
(iii) Expression Vectors

Hint:

Vectors differ in their features depending on purpose: Cosmids for large DNA, shuttle vectors for multiple hosts, expression vectors for protein production.

Answer 1

• (i) COSMIDS:
  • Capable of accommodating substantial DNA fragments, up to 45 kb.
  • Incorporate cos sites from bacteriophage lambda, enabling packaging into phage particles.
  • Feature bacterial origins of replication and antibiotic resistance genes for selection.
• (ii) Shuttle Vectors:
  • Possess origins of replication suitable for two distinct host species, such as E. coli and yeast.
  • Facilitate replication and selection across multiple host organisms.
  • Include selectable marker genes compatible with both hosts.
• (iii) Expression Vectors:
  • Contain potent promoter sequences for robust expression of inserted genes.
  • Include regulatory components such as operator sequences and ribosome binding sites.
  • Feature selectable markers and versatile multiple cloning sites.
  • Frequently incorporate tags (e.g., His-tag) to simplify the purification of produced proteins.