Nucleic Acids Research Advance Access originally published online on September 29, 2006
Nucleic Acids Research 2006 34(18):5337-5351; doi:10.1093/nar/gkl611
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Nucleic Acids Research, 2006, Vol. 34, No. 18 5337-5351
© 2006 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Molecular Biology |
A nucleosome assembly protein-like polypeptide binds to chloroplast group II intron RNA in Chlamydomonas reinhardtii
Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum D-44780 Bochum, Germany
*To whom correspondence should be addressed. Tel: +49 234 3226212; Fax: +49 234 3214184; Email: ulrich.kueck{at}ruhr-uni-bochum.de
Received May 2, 2006. Revised August 4, 2006. Accepted August 4, 2006.
In the unicellular green alga Chlamydomonas reinhardtii, the chloroplast-encoded tscA RNA is part of a tripartite group IIB intron, which is involved in trans-splicing of precursor mRNAs. We have used the yeast three-hybrid system to identify chloroplast group II intron RNA-binding proteins, capable of interacting with the tscA RNA. Of 14 candidate cDNAs, 13 encode identical polypeptides with significant homology to members of the nuclear nucleosome assembly protein (NAP) family. The RNA-binding property of the identified polypeptide was demonstrated by electrophoretic mobility shift assays using different domains of the tripartite group II intron as well as further chloroplast transcripts. Because of its binding to chloroplast RNA it was designated as NAP-like (cNAPL). In silico analysis revealed that the derived polypeptide carries a 46 amino acid chloroplast leader peptide, in contrast to nuclear NAPs. The chloroplast localization of cNAPL was demonstrated by laser scanning confocal fluorescence microscopy using different chimeric cGFP fusion proteins. Phylogenetic analysis shows that no homologues of cNAPL and its related nuclear counterparts are present in prokaryotic genomes. These data indicate that the chloroplast protein described here is a novel member of the NAP family and most probably has not been acquired from a prokaryotic endosymbiont.
Present address: Astrid Bunse, Qiagen GmbH, Qiagen Straße 1, D-40724 Hilden, Germany