title: Transcription of the apicoplast genome.
abstract: Many members of the Apicomplexa contain a remnant chloroplast, known as an apicoplast. The apicoplast encodes numerous genes, and loss of the organelle is lethal. Here, we present a summary of what is known about apicoplast transcription. Unlike plant chloroplasts, there is a single RNA polymerase, and initial transcription is polycistronic. RNA is then cleaved into tRNA, mRNA and rRNA molecules. Significant levels of antisense transcription have been reported, together with a single case of RNA editing. Polycistronic transcription is also observed in the related algae Chromera and Vitrella, which retain a photosynthetic chloroplast. Surprisingly, a polyU tail is added to Chromera and Vitrella transcripts which encode proteins involved in photosynthesis. No such tail is added to Plasmodium transcripts. Transcription in the Apicomplexa is remarkably similar to that seen in the chloroplast of the related peridinin dinoflagellate algae, reflecting the common evolutionary origins of the organelle.
authors.affiliation: Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK. Electronic address: rern2@cam.ac.uk.
authors.forename: R E R
authors.initials: RE
authors.lastname: Nisbet
authors.affiliation: Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK.
authors.forename: J L
authors.initials: JL
authors.lastname: McKenzie
mesh_terms: D016782:Apicomplexa / Q000235:genetics; D063546:Apicoplasts / Q000235:genetics*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004141:Dinoflagellida / Q000235:genetics; D005786:Gene Expression Regulation; D017125:Genes, Protozoan; D016678:Genome; D017393:RNA Editing; D012323:RNA Processing, Post-Transcriptional; D014158:Transcription, Genetic
chemical_list: D012321:DNA-Directed RNA Polymerases
keywords: Apicomplexa; Apicoplast; Chloroplast; Plastid; Post-transcriptional processing; Transcription