Transduction: A Novel Mechanism For Gene Transfer In Bacteriophages

Unlike normal bacteriophage infection, transduction involves the transfer of host cell genes into a bacteriophage, which then infects recipient cells. During phage lysogeny, phage DNA integrates into the host chromosome. Breakage of this DNA during packaging leads to transduction. Generalized transduction randomly packages host genes, while specialized transduction targets specific genes. This unique ability to transfer host genes makes transduction valuable for studying gene expression and regulation.

Transduction: A Peculiar Journey of Gene Transfer in Bacteria

Bacteriophages, viruses that attack bacteria, play a vital role in microbial ecology and genetics. While most phages relentlessly battle their bacterial foes, a select few have evolved a unique strategy: transduction, the transfer of host cell genes from one bacterium to another.

The Lysogenic Interlude: A Shelter within the Enemy

When a phage enters a bacterium, it faces a choice: destroy its host immediately or take a more subtle approach. In some cases, the phage may integrate its DNA into the bacterial chromosome, entering a dormant state known as lysogeny.

During lysogeny, the phage’s DNA, called a prophage, becomes a passenger within the bacterium, replicating alongside its host’s chromosomes. This close relationship, however, is not without consequences. The prophage’s presence can alter the bacterium’s behavior, giving rise to new traits and influencing its survival.

Transduction: A Broken Journey

Occasionally, the peaceful coexistence of phage and bacterium is disrupted by transduction. This process begins with a critical event: the random breakage of the host cell’s DNA. Unlike normal phage infections, the broken DNA fragments, not the phage’s own genome, are packaged into the newly assembled phage particles.

When these transducing phages infect a new bacterium, they inject their unusual cargo into the host cell: not their own genetic material, but a snippet of the previous host’s DNA. This introduces foreign genes into the新たな受容細胞, potentially altering its genetic makeup and evolutionary trajectory.

Transduction: A Unique Twist in Bacteriophage Infection

When bacteria face a bacteriophage invasion, they usually brace themselves for a fight or a takeover. But in a twist of events, some bacteriophages have evolved a new strategy: transduction. Instead of hijacking the host’s cell machinery, they play the role of molecular messengers, carrying host genes from one cell to another.

Generalized Transduction: A Scattered Messenger

In generalized transduction, the bacteriophage acts like a random courier. When it infects a host cell, it indiscriminately packages fragments of the host’s DNA along with its own. This genetic grab bag can include any part of the bacterial chromosome, resulting in a diverse range of gene transfers.

Specialized Transduction: Precision Gene Targeting

Specialized transduction, on the other hand, is a more targeted affair. The bacteriophage only integrates into a specific region of the host’s DNA, known as the attachment site. This precision allows it to carry specific genes from one host to another. The attachment site often contains genes that are important for the bacteriophage’s own survival or spread.

Key Differences Between Transduction and Normal Bacteriophage Infection

Genetic Material Transferred

• Normal infection: Phages inject their genetic material into the host cell, replacing the host’s own genetic material.
• Transduction: Phages package and transfer host cell genes, not their own.

Involvement of Lysogeny

• Normal infection: Phages typically enter a lytic cycle, destroying the host cell to release new phages.
• Transduction: Phages can enter a lysogenic cycle, where their DNA integrates into the host cell’s DNA, known as a prophage. This prophage can later be packaged into phages and transferred to other cells.

Specificity of Gene Transfer

• Generalized transduction: Phages package random host cell genes, leading to non-specific gene transfer.
• Specialized transduction: Phages package a specific set of host cell genes located near their own integration site in the host cell’s DNA. This results in precise gene transfer.