title: The group I intron of apocytochrome b gene from Chlamydomonas smithii encodes a site-specific endonuclease.
abstract: The mitochondrial DNA molecules of two interfertile algal species, Chlamydomonas smithii and C. reinhardtii, are co-linear except for a 1075 bp intron (the alpha-insert) that is present in the cob gene of C. smithii. The alpha-insert, a group I intron (Cs cob.1) containing an open reading frame (ORF) which encodes a basic, hydrophilic protein of 237 amino acids, is unidirectionally transmitted to all diploid progeny during interspecific crosses. In this report, we show that the Cs cob.1-encoded protein is a site-specific endonuclease (I-Csm I) which could mediate the intron transfer via the gene conversion mechanism. The Cs cob.1 ORF was cloned into the vector pMALcr1 and over-expressed as a hybrid protein fused to maltose-binding protein (MBP). This fusion protein exhibited an in vivo endonuclease activity which specifically cleaved the intron homing site within the intronless cob gene.
authors.affiliation: Department of Biochemistry and Molecular Biology, Mississippi State University 39762.
authors.forename: D P
authors.initials: DP
authors.lastname: Ma
authors.forename: Y T
authors.initials: YT
authors.lastname: King
authors.forename: Y
authors.initials: Y
authors.lastname: Kim
authors.forename: W S
authors.initials: WS
authors.lastname: Luckett
mesh_terms: D020418:Algal Proteins; D000818:Animals; D001059:Apoproteins / Q000235:genetics*; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics; D002696:Chlamydomonas / Q000201:enzymology / Q000235:genetics*; D003573:Cytochrome b Group / Q000235:genetics*; D045303:Cytochromes b; D004272:DNA, Mitochondrial / Q000235:genetics; D004706:Endodeoxyribonucleases / Q000235:genetics*; D004720:Endonucleases / Q000235:genetics*; D005785:Gene Conversion / Q000235:genetics; D005822:Genetic Vectors / Q000235:genetics*; D007438:Introns / Q000235:genetics*; D058619:Maltose-Binding Proteins; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D015800:Protozoan Proteins / Q000235:genetics; D016337:RNA, Catalytic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics
chemical_list: D020418:Algal Proteins; D001059:Apoproteins; D002352:Carrier Proteins; D003573:Cytochrome b Group; D004272:DNA, Mitochondrial; D058619:Maltose-Binding Proteins; D015800:Protozoan Proteins; D016337:RNA, Catalytic; D011993:Recombinant Fusion Proteins; D045303:Cytochromes b; D004706:Endodeoxyribonucleases; D004720:Endonucleases