title: Knockout of the plastid RNase E leads to defective RNA processing and chloroplast ribosome deficiency.
abstract: Ribonuclease E (RNase E) represents a key enzyme in bacterial RNA metabolism. It plays multifarious roles in RNA processing and also initiates degradation of mRNA by endonucleolytic cleavage. Plastids (chloroplasts) are derived from formerly free-living bacteria and have largely retained eubacterial gene expression mechanisms. Here we report the functional characterization of a chloroplast RNase E that is encoded by a single-copy nuclear gene in the model plant Arabidopsis thaliana. Analysis of knockout plants revealed that, unlike in bacteria, RNase E is not essential for survival. Absence of RNase E results in multiple defects in chloroplast RNA metabolism. Most importantly, polycistronic precursor transcripts overaccumulate in the knockout plants, while several mature monocistronic mRNAs are strongly reduced, suggesting an important function of RNase E in intercistronic processing of primary transcripts from chloroplast operons. We further show that disturbed maturation of a transcript encoding essential ribosomal proteins results in plastid ribosome deficiency and, therefore, provides a molecular explanation for the observed mutant phenotype.
authors.affiliation: Institut für Botanik, Universität Münster, Schlossplatz 4, 48149 Münster, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Walter
authors.forename: Katrin
authors.initials: K
authors.lastname: Piepenburg
authors.forename: Mark Aurel
authors.initials: MA
authors.lastname: Schöttler
authors.forename: Kerstin
authors.initials: K
authors.lastname: Petersen
authors.forename: Sabine
authors.initials: S
authors.lastname: Kahlau
authors.forename: Nadine
authors.initials: N
authors.lastname: Tiller
authors.forename: Oliver
authors.initials: O
authors.lastname: Drechsel
authors.forename: Magdalena
authors.initials: M
authors.lastname: Weingartner
authors.forename: Jörg
authors.initials: J
authors.lastname: Kudla
authors.forename: Ralph
authors.initials: R
authors.lastname: Bock
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D002736:Chloroplasts / Q000201:enzymology*; D018744:DNA, Plant / Q000235:genetics; D004722:Endoribonucleases / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D026723:Polyadenylation; D018747:RNA, Chloroplast / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*
chemical_list: D018744:DNA, Plant; D018747:RNA, Chloroplast; D004722:Endoribonucleases; C022537:ribonuclease E