The Discovery of DNA Polymerase: The Enzyme Behind DNA Replication

In 1953, James Watson and Francis Crick published their groundbreaking paper on the double-helix structure of DNA, suggesting that a mechanism for DNA replication was yet to be discovered. This challenge was taken up by Arthur Kornberg, an American biochemist, who sought to understand how nucleic acids are synthesized in living organisms. His research led to the discovery of DNA polymerase I in 1956, a landmark finding that revolutionized our understanding of DNA replication and repair.

Arthur Kornberg and the Discovery of DNA Polymerase I

Kornberg, working with the bacterium Escherichia coli, identified an enzyme that assembles DNA from its building blocks. This enzyme, named DNA polymerase I (pol I), is present in every living organism with slight variations. His early research papers on this discovery were initially rejected but were later published in 1957 in the Journal of Biological Chemistry. In 1959, Kornberg was awarded the Nobel Prize for uncovering the mechanisms of DNA synthesis.

DNA Polymerase: Nature’s Copy Machine

DNA polymerase I plays a vital role in DNA replication by:

1. Duplicating genetic material before cell division.
2. Ensuring that each daughter cell receives an exact copy of DNA.
3. Maintaining genetic continuity across generations.

This process is similar to a copy machine generating identical documents. However, unlike an ordinary copier, some subclasses of DNA polymerase, including pol I, possess a proofreading ability.

The Proofreading Function of DNA Polymerase

Certain types of DNA polymerases can:

• Detect and correct errors during replication.
• Remove incorrect nucleotides to prevent mutations.
• Ensure genetic stability by minimizing defects.

In contrast, some DNA polymerases lack proofreading capabilities, allowing mutations to persist, which can lead to genetic disorders or cell death.

There are seven subclasses of DNA polymerase (model shown). Some, such as pol I, engage in quality control—reading, detecting, and correcting errors in DNA prior to making a copy.