How does a genetically modified bacterium produce human insulin, and how is it used to treat diabetes?

Sourav PanNovember 12, 2024

Answered

The production of human insulin using genetically modified (GM) bacteria, particularly Escherichia coli (E. coli), is a significant advancement in biotechnology that has revolutionized diabetes treatment. Here’s how this process works and its application in treating diabetes.

Production of Human Insulin

1. Gene Isolation and Modification

• Gene Identification: The gene responsible for producing human insulin is located on chromosome 11 of the human genome. Scientists use restriction enzymes to isolate this gene, creating “sticky ends” that allow it to be easily inserted into another DNA molecule.
• Plasmid Preparation: A plasmid, which is a small circular piece of DNA found in bacteria, is also cut with the same restriction enzymes to create complementary sticky ends. This plasmid serves as a vector for the insulin gene.

2. Transformation

• Joining DNA: The isolated insulin gene is inserted into the plasmid using an enzyme called DNA ligase, which seals the DNA fragments together to form a recombinant plasmid.
• Bacterial Transformation: This recombinant plasmid is then introduced into E. coli cells through a process called transformation. The bacteria take up the plasmid and incorporate it into their own genetic material.

3. Cultivation and Insulin Production

• Fermentation: The transformed E. coli are cultured in large fermentation vessels under controlled conditions that provide optimal nutrients and temperature for growth. As the bacteria multiply, they replicate the plasmid containing the insulin gene.
• Insulin Synthesis: The bacteria express the human insulin gene, producing insulin protein as they grow. Initially, E. coli produces insulin as two separate chains (A and B chains) which are later combined to form active insulin through disulfide bond formation.

4. Purification

• After fermentation, the mixture containing E. coli cells and insulin is filtered to separate the insulin from bacterial cells. The insulin is then purified through various biochemical techniques to ensure it meets pharmaceutical standards.

Application in Diabetes Treatment

1. Insulin Therapy

• Type 1 Diabetes Management: Patients with type 1 diabetes lack sufficient insulin production due to autoimmune destruction of pancreatic beta cells. Recombinant human insulin provides a reliable source of insulin for these patients, helping to regulate blood glucose levels effectively.
• Type 2 Diabetes Treatment: In advanced cases of type 2 diabetes, where insulin resistance occurs, recombinant insulin can also be used to manage blood sugar levels when oral medications are insufficient.

2. Advantages of Recombinant Insulin

• Purity and Safety: Recombinant insulin produced by GM bacteria is purer than animal-derived insulins (previously sourced from pigs or cows), reducing the risk of allergic reactions and immune responses.
• Cost-Effectiveness: The ability to produce large quantities of insulin through fermentation makes it more affordable and accessible for patients worldwide.

3. Ongoing Research

Research continues into improving insulin production methods and exploring alternative delivery systems, such as genetically engineered bacteria that can secrete incretins or other hormones that stimulate insulin release directly in response to glucose levels in the gut