Evolution of Chloroplast Transcript Processing in Plasmodium and Its Chromerid Algal Relatives

Dorrell, Richard G.; Drew, James; Nisbet, R. Ellen R.; Howe, Christopher J.

Abstract

Chloroplasts contain their own genomes, containing two broad functional types of gene: genes encoding proteins directly involved in photosynthesis, and genes with a non-photosynthesis function, such as cofactor biosynthesis, assembly of protein complexes, or expression of the chloroplast genome. Thus far, to our knowledge, no chloroplast gene expression pathways in any lineage have been found to target one functional category of gene specifically. Here, we show that a chloroplast RNA processing pathway – the addition of a 3′ poly(U) tail – is specifically associated with photosynthesis genes in two species of algae, the ‘chromerids’ Chromera and Vitrella. The addition of the poly(U) tail enables the precise processing of mature photosynthesis gene transcripts from precursor RNA, and is likely to be essential for expression of the chromerid photosynthesis machinery. The chromerid algae are the closest photosynthetic relatives of a parasitic group of eukaryotes, the apicomplexans, which include the malaria pathogen Plasmodium. Apicomplexans are descended from algae, and retain a reduced chloroplast, which contains genes only of non-photosynthesis function. We have confirmed that 3′ poly(U) tails are not added to Plasmodium chloroplast transcripts. The expression pathways associated with photosynthesis genes have therefore been lost in the evolution of the apicomplexan chloroplast, and this loss could potentially have driven the transition from photosynthesis to parasitism.

• Journal Article Type: Article
• Acceptance Date: Oct 22, 2013
• Online Publication Date: Jan 16, 2014
• Publication Date: 2014-01
• Deposit Date: Jun 15, 2020
• Publicly Available Date: Jun 17, 2020
• Journal: PLoS Genetics
• Print ISSN: 1553-7390
• Publisher: Public Library of Science
• Peer Reviewed: Peer Reviewed
• Volume: 10
• Issue: 1
• Article Number: e1004008
• DOI: https://doi.org/10.1371/journal.pgen.1004008
• Keywords: Genetics(clinical); Genetics; Cancer Research; Ecology, Evolution, Behavior and Systematics; Molecular Biology
• Public URL: https://nottingham-repository.worktribe.com/output/4654890
• Publisher URL: https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1004008