Beautiful, but deadly to salmonella

Dec 19, 2011 By Cindy Weiss
Beautiful, but deadly to Salmonella
Mature virion. Credit: Carol Teschke

(PhysOrg.com) -- A virus that was first found in sewers and shares its name – P22 – with a semi-automatic handgun might seem an unlikely object of beauty.

But to Carolyn Teschke, professor of molecular and cell biology, P22 is not only beautiful, it has absorbed her attention since she was a postdoctoral researcher in the early ’90s at MIT.

She recently was awarded a renewal of her $1.2 million National Institutes of Health (NIH) grant to study how P22 assembles itself, knowledge that could one day be applied to other, more complex viruses. Ultimately, this type of basic research could help identify ways for drugs to target viruses, such as those that cause the flu or common colds.

P22, which infects only Salmonella bacteria, might itself become an object of interest – and beauty – to more than microbiologists. As bacteria become more and more resistant to antibiotics, interest is renewing in phage therapy – using bacteriophages (viruses that attack bacteria) to combat infections.

While phage therapy was first popularized in the early 20th century, the discovery of antibiotics overshadowed it. Now that antibiotics are losing effectiveness, clinical trials are being done in the U.S. on using phages to treat wounds, among other things. In other parts of the world, such as eastern Europe, phage therapy has long been more popular.

Bacteriophages have also been identified as potential defensive weapons in bio-warfare.

But Teschke’s interest in P22 is more basic. She wants to know how it forms its capsid, an outer shell of proteins that encapsulates its DNA. Each capsid of P22 has exactly 420 proteins – no more, no less – arranged in a sphere that is always the same size. It looks, Teschke says, like a perfect little soccer ball, only the inside contains genetic material.

“We don’t understand how the proteins know to do this,” she says. “And they generally don’t make mistakes.”

When P22 attacks Salmonella, its DNA takes over Salmonella’s own replication process to produce more of itself. Eventually, P22 overwhelms the .

Viruses have a wide variety of shapes and sizes, all starting with a protein. Knowing how they form would help scientists understand how to inhibit their formation and how to design drugs to do this.

P22 has a simpler structure than viruses such as HIV or herpes, making it an ideal subject for study. All of its double-stranded DNA has been identified, and biologists know what all of its proteins do. They can mutate it and see what changes, knowing which protein caused the change.

In altering it, “We find the ones that don’t make the right things,” says Teschke. By mutating P22, they can force it to form tubes instead of spheres, or to make spheres of the wrong size, for instance.

“So we can get ideas about what parts of the capsid protein are important to determine size or shape,” she says.

“We are hoping that by understanding a very simple , we’ll be able to translate that understanding to a more complex one.”

That would include any virus that has a capsid – such as the adenoviruses that cause respiratory infections like the common cold. A capsid inhibitor could then halt the virus’s formation at an early stage.

“It’s definitely possible that we could someday develop a drug that would specifically inhibit a particular virus,” she says.

Teschke’s research group includes graduate students Maggie Suhanovsky, Alex Rizzo, Pauline Padilla-Meier, Molly Siegel, undergraduate Jonathan Novak ’12 (CLAS), and grad student Nadia D’lima.

Explore further: How plant cell compartments change with cell growth

add to favorites email to friend print save as pdf

Related Stories

What does my child's sneeze mean?

Apr 26, 2011

(Medical Xpress) -- Though much of the beauty of spring is its vivid colors, rosy-red eyes and noses aren’t usually considered a welcome part of the landscape. Runny noses, sneezing and coughing often trumpet spring’s ...

Major breakthrough on how viruses infect plants

Jul 14, 2011

(PhysOrg.com) -- CSIRO plant scientists have shed light on a problem that has puzzled researchers since the first virus was discovered in 1892 – how exactly do they cause disease?

Recommended for you

How plant cell compartments change with cell growth

18 hours ago

A research team led by Kiminori Toyooka from the RIKEN Center for Sustainable Resource Science has developed a sophisticated microscopy technique that for the first time captures the detailed movement of ...

Plants can 'switch off' virus DNA

19 hours ago

A team of virologists and plant geneticists at Wageningen UR has demonstrated that when tomato plants contain Ty-1 resistance to the important Tomato yellow leaf curl virus (TYLCV), parts of the virus DNA ...

A better understanding of cell to cell communication

19 hours ago

Researchers of the ISREC Institute at the School of Life Sciences, EPFL, have deciphered the mechanism whereby some microRNAs are retained in the cell while others are secreted and delivered to neighboring ...

A glimpse at the rings that make cell division possible

20 hours ago

Forming like a blown smoke ring does, a "contractile ring" similar to a tiny muscle pinches yeast cells in two. The division of cells makes life possible, but the actual mechanics of this fundamental process ...

User comments : 0