An intron-encoded protein assists RNA splicing of multiple similar introns of different bacterial genes.
Four group II introns were found in an unusually intron-rich dnaN gene (encoding the beta subunit of DNA polymerase III) of the cyanobacterium Trichodesmium erythraeum, and they have strong similarities to two introns of the RIR gene (encoding ribonucleotide reductase) of the same organism. Of these six introns, only the RIR-3 intron encodes a maturase protein and showed efficient RNA splicing when expressed in Escherichia coli cells. The other five introns do not encode a maturase protein and did not show RNA splicing in E. coli. But these maturase-less introns showed efficient RNA splicing when the RIR-3 intron-encoded maturase protein was co-expressed from a freestanding gene in the same cell. These findings demonstrated that an intron-encoded protein could function as a general maturase for multiple introns of different genes. Major implications may include an intron-mediated co-regulation of the different genes and a resemblance of the evolutionary origin of spliceosomal introns.
Meng
Qing
Q
Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada.
Wang
Yanfei
Y
Liu
Xiang-Qin
XQ
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D000458:Cyanobacteria / Q000235:genetics*; D004258:DNA Polymerase III / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D015964:Gene Expression Regulation, Bacterial; D007438:Introns; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry; D012326:RNA Splicing; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012313:RNA; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase; C083980:dnaN protein, Bacteria