Some protists tend to depart from the universal genetic code, with frequent reassignments found in stop codons of flagellates. Unexpectedly, all three stop codons were recently shown to code for amino acids also in one trypanosome species. Still, one stop codon retains ambiguous meaning and acts both as a sense codon and as a termination codon. We are in the process of dissecting this enigmatic alteration of the genetic code in the trypanosomatid flagellate Blastocrithidia. We have sequenced and analyzed its genome, transcriptome and proteome, and in the process created an annotation software able to deal with this ambiguity. By analyzing the genome-wide distribution of the in-frame stops, we want to address questions such as: How does translation termination function without defined stop codons? How is translation influenced by numerous reassigned stop codons? What are the prerequisites that made this extensive and unique reassignment possible?

IPHYS Contact Person: Petr Pecina, petr.pecina@fgu.cas.cz