DURHAM, N.C. -- Biochemists from the University of Pennsylvania and Duke University Medical Center have reported analytical studies revealing unexpected new insights into how two very different molecules - a protein and an RNA - work together to form an enzyme that performs one of the fundamental tasks of constructing the protein-making machinery of the cell.
Their findings suggest that the partnership between the two molecules might represent an ancient remnant of an early era in life's evolution when RNA molecules were the enzymatic workhorses of primordial cells, before more versatile proteins evolved to take over the job.
The findings also may offer new targets for antibiotic compounds that could disrupt this key process in bacteria to kill them, the researchers said.
The biochemists reported in the May 1 issue of Science that they had obtained the crystal structure of the protein that is part of the enzyme "ribonuclease P." This enzyme is also known as a "ribozyme," because it is one in which the ribonucleic acid (RNA) functions as a catalyst.
Reporting their work were graduate student Travis Stams and Professor David Christianson of the University of Pennsylvania chemistry department; and Duke Medical Center postdoctoral fellow S. Niranjanakumari and Carol Fierke, associate professor of biochemistry. Their work is supported by the National Institutes of Health.
Ribonuclease P plays a key role in activating a molecule called transfer-RNA (tRNA) after it is first synthesized. Such tRNA molecules are the cellular equivalent of errand boys, latching onto individual subunits of proteins, called amino acids, to carry them to the cell's protein-making machinery, where the amino acids are chemically attached to one another in long stringlike molecules that fold into the cell's working proteins.
Specifically, ribonuclease P is a molecular scissors that helps turn
a newly synthesized precursor into a functioning tRNA
Contact: Dennis Meredith