Electron microscopy of the DT57C bacteriophage** (taken by transmission electron microscopy**) These types of images have been used to obtain the three-dimensional structure of the entire virus. Scale bar: 80 nm. **oist
The term "virus" is often associated with a negative connotation. However, it is important to note that not all viruses are harmful. In fact, there are many viruses that live in our bodies and play an important role in our health. An example is bacteriophage, a virus that infects bacteria and can be used to control bacterial infections.
These viruses are known to have more complex shapes and have not previously been studied in full detail at the atomic level. They can be designed to be more suitable for applications of human interest, such as providing an alternative to antibiotic use.
Scientists from the Okinawa University of Science and Technology (OIST), together with international collaborators from Moscow State University, Shenzhen University, and Taiwan** Research Institute, studied the molecular structure of Tequint**Irus, also known as T5-like bacteriophage, to understand how these viruses are organized at the molecular level.
T5 viruses are non-enveloped viruses with an icosahedral head that contains viral DNA and a flexible tail without shrinkage, which is a channel through which DNA is injected into the bacterial host cell.
Scientists have obtained atomic models of all the structural components of the virus. This is the first time that a tail virus with a flexible tail has been revealed in its entirety at this level of detail. Their findings have been published in the journal Nature Communications and provide a foundation for future studies of the infection mechanisms of these viruses.
In order to effectively design and modify these viruses for specific purposes, we must understand their tissues at the atomic level and the mechanisms by which they infect the target bacteria. For these reasons, we decided to use cryo-electron microscopy to visualize the DT57C bacteriophage in its entirety with high resolution," explains Prof. Matthias Wolf, Head of the Department of Molecular Cryo-Electron Microscopy.
Researchers studying bacteriophages** can benefit from the results of this study by using bacteriophages to**bacterial infections in crops, fish farming, and other areas. "The structural knowledge we gained could enable the engineering of bacteriophages with a higher ability to kill these bacterial pathogens," Professor Wolf added.
Does this mean that bacteriophages are "good" viruses?Dr. Rafael Ayala, lead author of the study, explained that these viruses are good when they behave well for us, and bad when they cause harm to us, just like bacteria.
An example of how bacteriophages can benefit us is their use in genes. "One of the ways to assign genes to cells is to put them in a human virus that is modified in two ways, firstly without causing disease, and secondly with the gene you want to introduce to a specific disease. In this way, the virus is used as a tool to introduce the ** method," Dr. Ayala said.
One of the main challenges of the study was the detailed reconstruction of the entire phage, not just some of its components, from electron microscopy**. The DT57C bacteriophage consists of a base plate at the head, neck, tail, and end of the tail. Many of these components are flexible and can move freely, which makes it difficult to visualize their molecular structure in detail, similar to how difficult it is to take a good picture of a fast-moving object.
To solve this problem, researchers have developed new methods, which they plan to apply to other viruses with complex shapes. "We have to come up with new ways to solve the problems we are experiencing, and we believe that the methods developed in this study will be of interest to many researchers working on the virus," Dr. Ayala explained. "Bacteriophages are an active area of research, and we are likely to see these methods in our lifetimes.
The use of viruses to modify bacteria is a huge area of interest, as bacteria are at the heart of many natural and engineered processes, including nutrition**, symbiosis, bioremediation (bacteria are used to clean up environmental contaminants), and food production. This research will help design viruses to fight bacterial diseases that affect humans, plants, and other organisms.
More information: Rafael Ayala et al., Near-complete structure of bacteriophage DT57C reveals structure of head-caudal interface and lateral tail fibers, Nature Communications (2023). doi： 10.1038/s41467-023-43824-9