Expression of intron-encoded maturase-like polypeptides in potato chloroplasts.
The trnK gene has been identified on a cloned plastid DNA fragment of potato (Solanum tuberosum cv Désirée). This gene codes for a tRNA-Lys and is interrupted by a 2.5-kb intron belonging to the group II organellar introns. In addition, this intervening sequence contains a long open reading frame potentially coding for a 509 amino-acid polypeptide (ORF509) related to mitochondrial intron-encoded maturases from fungi. The translational capacity of the trnK intron was first demonstrated in vitro in a prokaryotic DNA-directed expression system. In order to examine the expression of the intron in the potato plant, a synthetic peptide corresponding to the last nine amino acids of the predicted ORF509 product was used to raise antibodies. Western-blot experiments on chloroplast protein extracts, using a sensitive chemiluminescent detection system, identified polypeptides similar to in-vitro products. These results suggest that the trnK intron is expressed at the protein level in the plant. This is the first report of the in-vivo expression of an intron-encoded polypeptide in higher plant plastids.
du Jardin
P
P
Unité de Génétique et d'Amélioration des Plantes, Faculté des Sciences Agronomiques, Gemboux, Belgium.
Portetelle
D
D
Harvengt
L
L
Dumont
M
M
Wathelet
B
B
D000595:Amino Acid Sequence; D000818:Animals; D002736:Chloroplasts / Q000378:metabolism; D004722:Endoribonucleases / Q000737:chemistry*; D015870:Gene Expression; D007438:Introns / Q000235:genetics*; D007518:Isoantibodies / Q000276:immunology; D008969:Molecular Sequence Data; D009713:Nucleotidyltransferases / Q000737:chemistry*; D016366:Open Reading Frames / Q000235:genetics*; D010452:Peptide Biosynthesis; D010455:Peptides / Q000235:genetics; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D012357:RNA, Transfer, Lys / Q000096:biosynthesis / Q000235:genetics; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D011198:Solanum tuberosum / Q000235:genetics*
D007518:Isoantibodies; D010455:Peptides; D010940:Plant Proteins; D012357:RNA, Transfer, Lys; D011993:Recombinant Fusion Proteins; D009713:Nucleotidyltransferases; C034038:mRNA maturase; D004722:Endoribonucleases