Bacteriophage’s Long Tail Boosts Infection Capabilities

A recent study published in the Journal of Biological Chemistry has shed light on the secrets of a bacteriophage with an extremely long tail. The phage, which preys on some of the toughest bacteria on the planet, has a tail 10x longer than most, measuring nearly 1 micrometer long. Dubbed the “Rapunzel bacteriophage”, P74-26 has been found to be the most stable phage, allowing it to exist in and infect bacteria living in hot springs that can reach over 170°F. Researchers have been studying P74-26 to discover why and how it can exist in extreme environments.

The study’s lead author, Emily Agnello, described phages as being everywhere bacteria are, including in the dirt and water around us and in our bodies’ microbial ecosystems. Unlike many viruses infecting humans and animals that contain only one compartment, phages consist of a tail attached to a spiky, prismlike protein shell containing their DNA.

Phage tails are crucial for puncturing the dense, viscous substance that coats bacteria and P74-26’s long tail is optimized for invading and infecting formidable bacterium. Working with a phage that thrives in such high temperatures forced Agnello to adjust the experimental conditions to coax the phage tail to assemble itself in a test tube.

Using high-power imaging techniques and computer simulations, the researchers found that the tail’s building blocks lean on each other to stabilize themselves. They also found that P74-26 uses a “ball and socket” mechanism to sturdy itself.

Compared with most phages, P74-26 uses half the number of building blocks to form stacking rings that make up the tail, and the researchers believe that some ancient virus fused its building blocks into one protein, creating a larger, sturdier building block that could stabilize the tail at high temperatures.

Phages are essential to various industries, and long-tailed phages like P74-26 have been used in preliminary clinical trials to treat certain bacterial infections. The researchers now plan to use genetic manipulation to alter the length of the phage tail and see how that changes its behavior. The study of phage assembly could lead to the development of more effective phage-based therapies.