A group I intron in the chloroplast large subunit rRNA gene of Chlamydomonas eugametos encodes a double-strand endonuclease that cleaves the homing site of this intron. 1991

A Gauthier, and M Turmel, and C Lemieux
Départment de biochimie, Faculté des Sciences et de Génie, Université Laval, Québec, Canada.

During interspecific crosses between Chlamydomonas eugametos and Chlamydomonas moewusii, an optional group I intron of 955 base pairs (CeLSU.5) in the C. eugametos chloroplast large subunit rRNA gene undergoes a duplicative transposition event which is associated with frequent co-conversion of flanking cpDNA sequences. In the present study, we show that the basic protein of 218 amino acids encoded by CeLSU.5 could mediate the phenomenon of intron transposition, also called intron homing. We overexpressed the ORF specifying this protein in E. coli using expression vectors that contain a C. moewusii cpDNA sequence encompassing the intron homing site. The expression product was found to exhibit a double-strand DNA endonuclease activity that is specific for the homing site. This activity was detected in vivo by self-linearization of the expression plasmids.

UI MeSH Term Description Entries
D007438 Introns Sequences of DNA in the genes that are located between the EXONS. They are transcribed along with the exons but are removed from the primary gene transcript by RNA SPLICING to leave mature RNA. Some introns code for separate genes. Intervening Sequences,Sequences, Intervening,Intervening Sequence,Intron,Sequence, Intervening
D008969 Molecular Sequence Data Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories. Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D002696 Chlamydomonas A genus GREEN ALGAE in the order VOLVOCIDA. It consists of solitary biflagellated organisms common in fresh water and damp soil. Chlamydomona
D002736 Chloroplasts Plant cell inclusion bodies that contain the photosynthetic pigment CHLOROPHYLL, which is associated with the membrane of THYLAKOIDS. Chloroplasts occur in cells of leaves and young stems of plants. They are also found in some forms of PHYTOPLANKTON such as HAPTOPHYTA; DINOFLAGELLATES; DIATOMS; and CRYPTOPHYTA. Chloroplast,Etioplasts,Etioplast
D004275 DNA, Ribosomal DNA sequences encoding RIBOSOMAL RNA and the segments of DNA separating the individual ribosomal RNA genes, referred to as RIBOSOMAL SPACER DNA. Ribosomal DNA,rDNA
D004706 Endodeoxyribonucleases A group of enzymes catalyzing the endonucleolytic cleavage of DNA. They include members of EC 3.1.21.-, EC 3.1.22.-, EC 3.1.23.- (DNA RESTRICTION ENZYMES), EC 3.1.24.- (DNA RESTRICTION ENZYMES), and EC 3.1.25.-.
D005822 Genetic Vectors DNA molecules capable of autonomous replication within a host cell and into which other DNA sequences can be inserted and thus amplified. Many are derived from PLASMIDS; BACTERIOPHAGES; or VIRUSES. They are used for transporting foreign genes into recipient cells. Genetic vectors possess a functional replicator site and contain GENETIC MARKERS to facilitate their selective recognition. Cloning Vectors,Shuttle Vectors,Vectors, Genetic,Cloning Vector,Genetic Vector,Shuttle Vector,Vector, Cloning,Vector, Genetic,Vector, Shuttle,Vectors, Cloning,Vectors, Shuttle
D000595 Amino Acid Sequence The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION. Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D001483 Base Sequence The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence. DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D012335 RNA, Ribosomal The most abundant form of RNA. Together with proteins, it forms the ribosomes, playing a structural role and also a role in ribosomal binding of mRNA and tRNAs. Individual chains are conventionally designated by their sedimentation coefficients. In eukaryotes, four large chains exist, synthesized in the nucleolus and constituting about 50% of the ribosome. (Dorland, 28th ed) Ribosomal RNA,15S RNA,RNA, 15S

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