Submitted on January 8, 2008
Accepted on March 7, 2008
Metabolic Diversification—Independent Assembly of Operon-Like Gene Clusters in Plants
Ben Field 1 and Anne E. Osbourn 1*
1 Department of Metabolic Biology, John Innes Centre, Colney Lane, Norwich, NR4 7UH, UK.
* To whom correspondence should be addressed.
Anne E. Osbourn , E-mail: anne.osbourn{at}bbsrc.ac.uk
Operons are clusters of unrelated genes with related functions that are a feature of prokaryotic genomes. Here we report on an operon-like gene cluster in the plant Arabidopsis thaliana that is required for triterpene synthesis (the thalianol pathway). The clustered genes are coexpressed, as in bacterial operons. However, despite the resemblance to a bacterial operon, this gene cluster has been assembled from plant genes by gene duplication, neofunctionalization and genome reorganization rather than by horizontal gene transfer from bacteria. Furthermore, recent assembly of operon-like gene clusters for triterpene synthesis has occurred independently in divergent plant lineages (Arabidopsis and oat). Thus selection pressure may act during the formation of certain plant metabolic pathways to drive gene clustering.
