Staphylococcus Epidermidis Bacteriophage

Staphylococcus Epidermidis Bacteriophage Atomic Structure Revealed By Cryo-Electron Microscopy

As per the latest findings, Birmingham researchers have revealed the atomic structure of Staphylococcus epidermidis bacteriophage using Cryo-electron microscopy.

he research itself looks quite accomplished as the researchers have managed to expose the structure of a bacterial virus with precise detail.

Bacteriophages are the virus infecting bacteria. Researchers like Asma Hatoum-Aslan, Ph.D., at the University of Illinois Urbana-Champaign in association with Terje Dokland, Ph.D. at the University of Illinois Urbana-Champaign have unleashed the atmoic models of 11 different structural proteins in phage Andhra.

The above study has been published in phage Andhra which is a member of picovirus group. The skin bacterium is mostly known to be a leading cause of infections.

This is what one of the researchers have to say, . “Picoviruses are rarely found in phage collections and remain understudied and underused for therapeutic applications,” he said.

With emergence of antibiotic resistance in S. epidermidis and the related pathogen Staphylococcus aureus, researchers have renewed interest in potentially using bacteriophages to treat bacterial infections. Picoviruses always kill the cells they infect, after binding to the bacterial cell wall, enzymatically breaking through that wall, penetrating the cell membrane and injecting viral DNA into the cell. They also have other traits that make them attractive candidates for therapeutic use, including a small genome and an inability to transfer bacterial genes between bacteria.

Knowledge of protein structure in Andhra and understanding of how those structures allow the virus to infect a bacterium will make it possible to produce custom-made phages tailored to a specific purpose, using genetic manipulation.

 

The structural basis for host specificity between phages that infect S. aureus and S. epidermidis is still poorly understood. With the present study, we have gained a better understanding of the structures and functions of the Andhra gene products and the determinants of host specificity, paving the way for a more rational design of custom phages for therapeutic applications. Our findings elucidate critical features for virion assembly, host recognition and penetration.”

 

Terje Dokland, professor of microbiology at UAB and director of the UAB Cryo-Electron Microscopy Core

 

Also Read: COVID Induced Disruptions May Lead to the Return of Measles

Staphylococcal phages typically have a narrow range of bacteria they can infect, depending on the variable polymers of wall teichoic acid on the surface of different bacterial strains. “This narrow host range is a double-edged sword: On one hand, it allows the phages to target only the specific pathogen causing the disease; on the other hand, it means that the phage may need to be tailored to the patient in each specific case,” Dokland said.

The general structure of Andhra is a 20-faced, roundish icosahedral capsid head that contains the viral genome. The capsid is attached to a short tail. The tail is largely responsible for binding to S. epidermidis and enzymatically breaking the cell wall. The viral DNA is injected into the bacterium through the tail. Segments of the tail include the portal from the capsid to the tail, and the stem, appendages, knob and tail tip.

Electron microscopes use a beam of accelerated electrons to illuminate an object, providing much higher resolution than a light microscope.

In the past eight years, new electron detectors have created a tremendous jump in resolution for cryo-electron microscopy over normal electron microscopy. Key elements of this so-called “resolution revolution” for cryo-electron microscopy are:

    • Flash-freezing aqueous samples in liquid ethane cooled to below -256 degrees F. Instead of ice crystals that disrupt samples and scatter the electron beam, the water freezes to a window-like “vitreous ice.”
    • The sample is kept at super-cold temperatures in the microscope, and a low dose of electrons is used to avoid damage to the proteins.
    • Extremely fast direct electron detectors are able to count individual atoms at hundreds of frames per second, allowing sample movement to be corrected on the fly.
    • Advanced computing merges thousands of images to generate three-dimensional structures at high resolution. Graphics processing units are used to churn through terabytes of data.
    • The microscope stage that holds the sample can also be tilted as images are taken, allowing construction of a three-dimensional tomographic image, similar to a CT scan at the hospital.

The analysis of Andhra virion structure by the UAB researchers started with 230,714 particle images. Molecular reconstruction of the capsid, tail, distal tail and tail tip started with 186,542, 159,489, 159,489 and 159,489 images, respectively. Resolution ranged from 3.50 to 4.90 angstroms.

 

Source:

Journal reference:

Hawkins, N.C., et al. (2022) Structure and host specificity of Staphylococcus epidermidis bacteriophage Andhra. Science Advances. doi.org/10.1126/sciadv.ade0459.

 

Leave a Comment

Scroll to Top