This Article Full Text Full Text (PDF) All Versions of this Article: 19/11/3627    most recent tpc.107.051722v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Schwarz, C. Articles by Nickelsen, J. Search for Related Content PubMed PubMed Citation Articles by Schwarz, C. Articles by Nickelsen, J. Agricola Articles by Schwarz, C. Articles by Nickelsen, J.

Synthesis of the D2 Protein of Photosystem II in Chlamydomonas Is Controlled by a High Molecular Mass Complex Containing the RNA Stabilization Factor Nac2 and the Translational Activator RBP40

^a Molekulare Pflanzenwissenschaften, Ludwig-Maximilians Universität München, 80638 Munich, Germany
^b Pflanzenphysiologie, Ruhr-Universität Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany

² Address correspondence to joerg.nickelsen{at}lrz.uni-muenchen.de.

Gene expression in chloroplasts is regulated mainly at the posttranscriptional level. In the green alga Chlamydomonas reinhardtii, synthesis of the D2 protein (PsbD), which is the rate-determining subunit for the assembly of photosystem II, depends on the RNA stability factor Nac2. In addition, the RNA binding protein RBP40 has been implicated in translational control via a U-rich element in the 5' untranslated region (5'UTR) of the psbD mRNA. Here, we report the identification of the RBP40 gene based on mass spectrometric analysis of its purified product. Unexpectedly, this was found to be identical to the previously described RNA binding protein RB38, which had been suggested to be involved in the regulation of D1 protein synthesis. However, we show that RBP40 binds to the psbD 5'UTR in a Nac2-dependent fashion both in vitro and in vivo. Molecular characterization of RBP40 RNA interference lines confirmed that RBP40 specifically affects the initiation of D2 synthesis. Native polyacrylamide gel electrophoresis, coimmunoprecipitation, and sedimentation analyses revealed that Nac2 and RBP40 form parts of a complex of 550 kD that is displaced from the psbD mRNA prior to polysome assembly. Together, these data indicate that the processes of 5'UTR-mediated RNA stabilization and translation initiation are tightly coupled in Chlamydomonas.

This article has been cited by other articles:

				C. Loiselay, N. J. Gumpel, J. Girard-Bascou, A. T. Watson, S. Purton, F.-A. Wollman, and Y. Choquet Molecular Identification and Function of cis- and trans-Acting Determinants for petA Transcript Stability in Chlamydomonas reinhardtii Chloroplasts Mol. Cell. Biol., September 1, 2008; 28(17): 5529 - 5542. [Abstract] [Full Text] [PDF]

				J. Uniacke and W. Zerges Photosystem II Assembly and Repair Are Differentially Localized in Chlamydomonas PLANT CELL, November 1, 2007; 19(11): 3640 - 3654. [Abstract] [Full Text] [PDF]