title: A nucleosome assembly protein-like polypeptide binds to chloroplast group II intron RNA in Chlamydomonas reinhardtii.
abstract: 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.
authors.affiliation: Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Glanz
authors.forename: Astrid
authors.initials: A
authors.lastname: Bunse
authors.forename: Andrea
authors.initials: A
authors.lastname: Wimbert
authors.forename: Carsten
authors.initials: C
authors.lastname: Balczun
authors.forename: Ulrich
authors.initials: U
authors.lastname: Kück
mesh_terms: D020418:Algal Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D016825:Chlamydomonas reinhardtii / Q000235:genetics* / Q000378:metabolism; D002736:Chloroplasts / Q000737:chemistry / Q000235:genetics*; D007438:Introns; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics; D009707:Nucleosomes / Q000378:metabolism; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D048030:RNA, Algal / Q000737:chemistry / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques
chemical_list: D020418:Algal Proteins; D009687:Nuclear Proteins; D009707:Nucleosomes; D010455:Peptides; D048030:RNA, Algal; D012333:RNA, Messenger; D016601:RNA-Binding Proteins