In vivo testing of a tobacco plastid DNA segment for guide RNA function in psbL editing.
A C-to-U RNA editing event creates a functional initiation codon for translation of the psbL mRNA in tobacco plastids. Small trans-acting guide RNAs (gRNAs) have been shown to be involved in editing site selection in kinetoplastid mitochondria. A computer search of the tobacco plastid genome (ptDNA) identified such a putative gRNA, a 14-nucleotide sequence motif that is complementary to the psbL mRNA, including the A nucleotide required to direct the C-to-U change. The critical A nucleotide of the putative gRNA gene was changed to G by plastid transformation. We report here that the introduced mutation did not abolish psbL editing. Since no other region of the plastid genome contains significant complementarity to the psbL editing site we suggest that, if gRNAs serve as trans-acting factors for plastid psbL mRNA editing, they either have only a limited complementarity to the editing site, or are encoded in the nuclear genome.
Bock
R
R
Waksman Institute, Rutgers, State University of New Jersey, Piscataway 08855-0759, USA.
Maliga
P
P
D001483:Base Sequence; D017931:DNA Primers / Q000737:chemistry; D018742:DNA, Chloroplast / Q000235:genetics*; D017343:Genes, Plant; D008969:Molecular Sequence Data; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics*; D045332:Photosystem II Protein Complex; D010940:Plant Proteins / Q000235:genetics; D010947:Plants, Toxic; D018087:Plastids / Q000235:genetics*; D017393:RNA Editing; D012323:RNA Processing, Post-Transcriptional; D017394:RNA, Guide, Kinetoplastida / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D014026:Nicotiana / Q000235:genetics*
D017931:DNA Primers; D018742:DNA, Chloroplast; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D012333:RNA, Messenger; C075419:photosystem II, psbL subunit; D017394:RNA, Guide, Kinetoplastida