New Research
Molecule that ‘blocks’ key bacterial enzyme may lead to new antibiotics
Archived article from Sep 20, 2004
By Joseph Blumberg
Scientists at Rutgers’ Waksman Institute of Microbiology have deciphered the complex mechanics of microcin J25 (MccJ25), a tiny, natural molecule that acts like a cork in a bottle to block a key bacterial enzyme – potentially leading to a new generation of antibiotics.
Two teams of researchers at the institute describe in separate reports how each group used different experimental methods to reach the same conclusions in the journal “Molecular Cell” in June.
Richard Ebright, a Howard Hughes Medical Institute investigator, and his colleagues; and Konstantin Severinov, an associate professor in the department of molecular biology and biochemistry, and members of his research team, discovered independently that MccJ25 uniquely blocks a "tunnel" into the bacterial enzyme, RNA polymerase (RNAP). The tunnel is used to bring raw materials for RNA synthesis into the enzyme and to expel byproducts of RNA synthesis.
“Closing the crowded, two-way ‘tunnel’ starves RNAP, shuts it down and kills the bacteria,” said Ebright, who is also a professor in the department of chemistry and chemical biology.
Understanding the way in which MccJ25 works sets the stage for the development of novel antibacterial drug designs. Ebright’s group used genetic methods to test hundreds of thousands of RNAP derivatives that define the binding sites for MccJ25 on RNAP.
The researchers also used biophysical methods, attaching fluorescent tags to MccJ25 and to each of a dozen sites in RNAP. Using the tags, they gauged the position of each bound pair, verifying the results of the genetic work. They then used biochemical methods to find out what happened once MccJ25 binds to the RNAP.
Severinov’s research team had been the first to demonstrate that RNAP from cells resistant to MccJ25 also showed resistance to the drug in a test tube. In their current work, these researchers used biochemical methods to characterize, in molecular detail, the mechanism of MccJ25 action.
In addition, Severinov’s group used sophisticated biophysical methods that revealed how MccJ25 binds to a single RNAP molecule, stopping it instantaneously.
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