The Virus That Makes a Disposable Syringe

Researchers have discovered a tube-shaped structure that forms temporarily in a certain type of virus to deliver its DNA during the infection process and then dissolves after its job is completed. The tube is long enough to span the inner and outer cell membranes of an E. coli bacterium, bridging the
Researchers have discovered a tube-shaped structure that forms temporarily in a certain type of virus to deliver its DNA during the infection process and then dissolves after its job is completed. The tube is long enough to span the inner and outer cell membranes of an E. coli bacterium, bridging the "periplasmic space" in between. (Image: Lei Sun/Purdue University)

A research team led by the University of Arizona and Purdue University has discovered something very unique about a virus that has been studied for decades: It has the ability to grow a temporary tube-shaped structure, enabling it to inject its DNA into the bacteria on which it preys.
 
The finding solves an almost century-long mystery.
 
Typically, a virus will use a tail-like structure to deliver its DNA. The question was how that transfer happened in viruses with no apparent "tail." The explanation was found by examining phiX174, a bacteriophage that preys on E. coli bacteria, which is able to grow a tube-like structure to do the job – and then disassemble that structure after infection.
 
The discovery, published in the journal Nature, represents the first known viral DNA-transmitting structure that has been decoded at the atomic scale and could hold implications for nanotechnology and medical research.
 
Most bacteriophages, as viruses that specifically attack bacteria are called, have a tail-like structure that they use to attach to the bacteria's cell wall, punch a hole in it and insert their own genetic material in an effort to hijack the cell's machinery to produce more viruses. Not so phiX174, a bacteriophage that preys on E. coli bacteria. This bacteriophage is in a class of viruses that do not contain an obvious tail section for the transfer of its DNA into host cells
 
"Since this virus was discovered in the 1920's, no one knew how the DNA got into the cell," said Bentley Fane, a professor in the School of Plant Sciences in the UA College of Agriculture and Life Sciences, "because phiX doesn't have a visible tail."
 
"But, lo and behold, it appears to make its own tail," said Michael Rossmann, the Hanley Distinguished Professor of Biological Sciences at Purdue University, who led the research project together with Fane. "It doesn’t carry its tail around with it, but when it is about to infect the host it makes a tail."
 
Researchers were surprised to discover the fleeting tail.

Read more from this December 17 UANews article at the link below.

Date released: 
Dec 19 2013
Contact: 
Bentley Fane