Email updates

Keep up to date with the latest news and content from BMC Biology and BioMed Central.

Journal App

google play app store
Open Access Highly Accessed Research article

Complex chloroplast RNA metabolism: just debugging the genetic programme?

Uwe G Maier1*, Andrew Bozarth1, Helena T Funk1, Stefan Zauner1, Stefan A Rensing2, Christian Schmitz-Linneweber3, Thomas Börner3 and Michael Tillich3

Author Affiliations

1 Philipps University Marburg, Cell Biology, Karl-von-Frisch Str., D-35032, Marbur, Germany

2 University of Freiburg, Faculty of Biology, Schaenzlestr. 1, D-79104, Freiburg, Germany

3 Humboldt University Berlin, Institute of Biology, Chausseestr. 117, D-10115, Berlin, Germany

For all author emails, please log on.

BMC Biology 2008, 6:36  doi:10.1186/1741-7007-6-36

Published: 28 August 2008

Abstract

Background

The gene expression system of chloroplasts is far more complex than that of their cyanobacterial progenitor. This gain in complexity affects in particular RNA metabolism, specifically the transcription and maturation of RNA. Mature chloroplast RNA is generated by a plethora of nuclear-encoded proteins acquired or recruited during plant evolution, comprising additional RNA polymerases and sigma factors, and sequence-specific RNA maturation factors promoting RNA splicing, editing, end formation and translatability. Despite years of intensive research, we still lack a comprehensive explanation for this complexity.

Results

We inspected the available literature and genome databases for information on components of RNA metabolism in land plant chloroplasts. In particular, new inventions of chloroplast-specific mechanisms and the expansion of some gene/protein families detected in land plants lead us to suggest that the primary function of the additional nuclear-encoded components found in chloroplasts is the transgenomic suppression of point mutations, fixation of which occurred due to an enhanced genetic drift exhibited by chloroplast genomes. We further speculate that a fast evolution of transgenomic suppressors occurred after the water-to-land transition of plants.

Conclusion

Our inspections indicate that several chloroplast-specific mechanisms evolved in land plants to remedy point mutations that occurred after the water-to-land transition. Thus, the complexity of chloroplast gene expression evolved to guarantee the functionality of chloroplast genetic information and may not, with some exceptions, be involved in regulatory functions.