The Duke researchers performed chemical experiments that confirmed this contact, producing altered versions of the protein that would chemically cross-link with the RNA in the cleft, allowing them to unequivocally determine that the protein was holding the RNA.
The Duke researchers also are tinkering with the protein's structure to explore a potential third key RNA binding region on the protein that may help the RNA of the ribonuclease P grab magnesium atoms that it needs to function optimally.
Such findings may offer intriguing insights into how the machinery of living cells first evolved, Fierke said.
"We really didn't expect such a role for the protein," she said. "And, if it turns out to be true, one could speculate that one of the reasons life evolved from an RNA-dependent world to a protein-dependent world is that the RNA required magnesium to do anything. And RNA is not particularly good at forming specific metal binding sites, whereas proteins are particularly good."
The biochemists' work might offer new targets for antibiotics, since ribonuclease P is essential for making all tRNAs, and since the bacterial enzyme is different from the enzyme in higher organisms. Thus, both the Duke and University of Pennsylvania groups propose to design inhibitor compounds that will block some aspect of the critical contacts among the protein, the RNA portion of the ribozyme, and the pre-tRNA.
"There are a great many places one could target to thwart this enzyme," Fierke said.