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Raa4 is a trans ‐splicing factor that specifically binds chloroplast tscA intron RNA
Author(s) -
Glanz Stephanie,
Jacobs Jessica,
Kock Vera,
Mishra Arti,
Kück Ulrich
Publication year - 2012
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2011.04801.x
Subject(s) - intron , rna splicing , biology , group ii intron , chlamydomonas reinhardtii , exon , gene , rna , trans splicing , genetics , complementation , sr protein , exonic splicing enhancer , rna binding protein , microbiology and biotechnology , mutant
Summary During trans ‐splicing of discontinuous organellar introns, independently transcribed coding sequences are joined together to generate a continuous mRNA. The chloroplast psaA gene from Chlamydomonas reinhardtii encoding the P 700 core protein of photosystem I (PSI) is split into three exons and two group IIB introns, which are both spliced in trans . Using forward genetics, we isolated a novel PSI mutant, raa4 , with a defect in trans ‐splicing of the first intron. Complementation analysis identified the affected gene encoding the 112.4 kDa Raa4 protein, which shares no strong sequence identity with other known proteins. The chloroplast localization of the protein was confirmed by confocal fluorescence microscopy, using a GFP‐tagged Raa4 fusion protein. RNA‐binding studies showed that Raa4 binds specifically to domains D2 and D3, but not to other conserved domains of the tripartite group II intron. Raa4 may play a role in stabilizing folding intermediates or functionally active structures of the split intron RNA.