title: A cyanobacterial strain with all chromosomal rRNA operons inactivated: a single nucleotide mutation of 23S rRNA confers temperature-sensitive phenotypes.
abstract: The presence of a multicopy chromosome, with each copy containing two rRNA operons (rrnA and rrnB), has been an obstacle to analysing mutated rRNA in Synechococcus PCC 7942. To create a system for expressing homogeneous mutated rRNA, the chromosomal rrn operons were sequentially inactivated and a final strain was successfully obtained with all the chromosomal rrn operons inactivated but carrying a replaceable multicopy plasmid containing a single rrn operon. The lag time required for growth response on dark/light shift of mutant strains with chromosomal rrnA or rrnB inactivated was increased 50 % over that of the wild-type strain; however, the presence of the plasmid-borne rrn operon restored the lag time. The doubling time of mutant strains carrying only a functional rrnB operon, but not strains carrying only a functional rrnA operon, was significantly longer than that of the wild-type strain. A strain in which essentially all the cellular 23S rRNA contained the mutation C2588A was temperature sensitive at 16 degrees C and 45 degrees C. Position C2588 is equivalent to C2611 of the peptidyltransferase centre in domain V of Escherichia coli 23S rRNA.
authors.affiliation: Institute of Molecular Biology and Genetics, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand.
authors.forename: Tanakarn
authors.initials: T
authors.lastname: Monshupanee
authors.affiliation: Institute of Molecular Biology and Genetics, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand.
authors.forename: Sirirat
authors.initials: S
authors.lastname: Fa-Aroonsawat
authors.affiliation: Institute of Molecular Biology and Genetics, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand.
authors.forename: Wipa
authors.initials: W
authors.lastname: Chungjatupornchai
mesh_terms: D001483:Base Sequence; D015139:Blotting, Southern; D004926:Escherichia coli; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009690:Nucleic Acid Conformation; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D017354:Point Mutation; D012338:RNA, Ribosomal, 23S / Q000235:genetics*; D017384:Sequence Deletion; D046940:Synechococcus / Q000235:genetics* / Q000254:growth & development; D013696:Temperature; D012407:rRNA Operon / Q000235:genetics*
chemical_list: D012338:RNA, Ribosomal, 23S