The chloroplast chlL gene of the green alga Chlorella vulgaris C-27 contains a self-splicing group I intron.
The chlL gene product is involved in the light-independent synthesis of chlorophyll in photosynthetic bacteria, green algae and non-flowering plants. The chloroplast genome of Chlorella vulgaris strain C-27 contains the first example of a split chlL gene, which is interrupted by 951 bp group I intron in the coding region. In vitro synthesized pre-mRNA containing the entire intron and parts of the flanking exon sequence is able to efficiently self-splice in vitro in the presence of a divalent and a monovalent cation and GTP, to yield the ligated exons and other splicing intermediates characteristic of self-splicing group I introns. The 5' and 3' splice sites were confirmed by cDNA sequencing and the products of the splicing reaction were characterized by primer extension analysis. The absence of a significant ORF in the long P9 region (522 nt), separating the catalytic core from the 3' splice site, makes this intron different from the other known examples of group I introns. Guanosine-mediated attack at the 3' splice site and the presence of G-exchange reaction sites internal to the intron are some other properties demonstrated for the first time by an intron of a protein-coding plastid gene.
Kapoor
M
M
Center for Gene Research, Nagoya University, Japan.
Wakasugi
T
T
Yoshinaga
K
K
Sugiura
M
M
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D002708:Chlorella / Q000737:chemistry / Q000235:genetics*; D002734:Chlorophyll / Q000096:biosynthesis; D002736:Chloroplasts / Q000737:chemistry / Q000235:genetics*; D017124:Conserved Sequence; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D005796:Genes; D006160:Guanosine Triphosphate / Q000378:metabolism; D007438:Introns / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D016366:Open Reading Frames / Q000235:genetics; D011506:Proteins / Q000737:chemistry / Q000235:genetics*; D012322:RNA Precursors / Q000737:chemistry / Q000378:metabolism; D012326:RNA Splicing / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid
D017931:DNA Primers; D011506:Proteins; D012322:RNA Precursors; D002734:Chlorophyll; D006160:Guanosine Triphosphate