( ith its small subunit. In the new study...)North & South American researchers find architectural abnormalities in T. cruzi ribosome

The researchers found a gigantic addition tacked onto one side of the small subunit, resembling a turret topped by a spire. "It's larger than anything we've seen anywhere, as far as peripheral additions in ribosomes are concerned," Frank said. "It's almost freestanding."

The exact purpose of the turret and its spire is unknown, but the researchers suspect the function will be as unique as its architecture. They speculate that it may have something to do with the 39-nucleotide leader of the mRNA that the parasite's ribosomes must process. The spot where the ribosome binds to the mRNA, for example, is roughly as far away from the turret and spire as the length of the 39-nucleotide leader sequence.

"It could provide a unique scanning mechanism different from other eukaryotes," Frank said. "For instance, the splice leader of the mRNA might attach at the turret, which may swivel out and drag the mRNA across the binding site on the ribosome to initiate protein translation."

The findings may also advance studies of parasitic relatives Trypanosoma brucei, which causes sleeping sickness in Africa, and Leishmania, a parasite spread by sand flies. Higher resolution models of the ribosome structure will be needed to design targeted drugs, Frank said.