The human malaria parasite, Plasmodium falciparum,
maintains at least two distinct types, A and S, of developmentally
controlled ribosomal RNAs. To investigate specific functions
associated with these rRNAs, we replaced the Saccharomyces
cerevisiae GTPase domain of the 25S rRNA with GTPase
domains corresponding to the Plasmodium A- and
S-type 28S rRNAs. The A-type rRNA differs in a single nonconserved
base pair from the yeast GTPase domain. The S-type rRNA
GTPase domain has three additional changes in highly conserved
residues, making it unique among all known rRNA sequences.
The expression of either A- or S-type chimeric rRNA in
yeast increased translational accuracy. Yeast containing
only A-type chimeric rRNA and no wild-type yeast rRNA grew
at the wild-type level. In contrast, S-type chimeric rRNA
severely inhibited growth in the presence of wild-type
yeast rRNA, and caused lethality in the absence of the
wild-type yeast rRNA. We show what before could only be
hypothesized, that the changes in the GTPase center of
ribosomes present during different developmental stages
of Plasmodium species can result in fundamental
changes in the biology of the organism.