title: DNA macroarray and real-time PCR analysis of two nuclear photosystem I mutants from Chlamydomonas reinhardtii reveal downregulation of Lhcb genes but different regulation of Lhca genes.
abstract: In photoautotrophic organisms, the expression of nuclear genes encoding plastid proteins is known to be regulated at various levels. In this study, we present the analysis of two non-photosynthetic mutants (CC1051 and TR72) from the unicellular green alga Chlamydomonas reinhardtii. Both mutant strains show a defect in the processing of chloroplast psaA mRNA, and therefore they are assumed to be defective in photosystem I (PSI) assembly. We have performed macroarray experiments with trans-splicing mutants CC1051 and TR72 in order to analyse putative pleiotropic effects of nuclear-located mutations leading to a non-functional PSI. To the best of our knowledge, this is the first example of Chlamydomonas cDNA macroarray analysis comparing the transcriptional regulation of nuclear genes in wild-type and photosystem I mutants. The macroarray results demonstrated a transcriptional downregulation of members of the Lhcb gene family more than 2-fold in both mutant strains. In addition, real-time RT-PCR experiments found a 4- to 16-fold reduction in transcript levels of several Lhca genes in TR72; whereas in CC1051, no significant change in transcript levels was observed. Taken together, our data suggest that a signal is transmitted from the chloroplast to the nucleus that serves to regulate the level of light harvesting polypeptides in the organelle.
authors.affiliation: Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Balczun
authors.forename: Astrid
authors.initials: A
authors.lastname: Bunse
authors.forename: Minou
authors.initials: M
authors.lastname: Nowrousian
authors.forename: Alexandra
authors.initials: A
authors.lastname: Korbel
authors.forename: Stephanie
authors.initials: S
authors.lastname: Glanz
authors.forename: Ulrich
authors.initials: U
authors.lastname: Kück
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D016825:Chlamydomonas reinhardtii / Q000235:genetics*; D015536:Down-Regulation / Q000235:genetics*; D045342:Light-Harvesting Protein Complexes / Q000235:genetics*; D005810:Multigene Family; D009154:Mutation / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D045331:Photosystem I Protein Complex / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex