RT Journal Article SR Electronic(1) A1 Monshupanee, Tanakarn A1 Fa-aroonsawat, Sirirat A1 Chungjatupornchai, WipaYR 2006 T1 A cyanobacterial strain with all chromosomal rRNA operons inactivated: a single nucleotide mutation of 23S rRNA confers temperature-sensitive phenotypes JF Microbiology, VO 152 IS 5 SP 1417 OP 1425 DO https://doi.org/10.1099/mic.0.28691-0 PB Microbiology Society, SN 1465-2080, AB 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 °C and 45 °C. Position C2588 is equivalent to C2611 of the peptidyltransferase centre in domain V of Escherichia coli 23S rRNA., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.28691-0