Sequence evidence for an altered genetic code in the Neospora caninum plastid

The plastid DNA of Neospora caninum encodes a homologue of the rpoB gene, w hich is believed to encode a subunit of a bacterial or chloroplast-like RNA polymerase. The predicted protein product of the N. caninum rpoB gene has three in-frame UGA codons which appear to encode tryptophan residues rather than act as stop codons. Based on the nucleotide sequence of a portion of the ssrRNA gene of the N. caninum plastid, a model for suppression of UGA t ermination in this plastid is presented. (C) 1999 Australian Society for Pa rasitology Inc. Published by Elsevier Science Ltd. All rights reserved.