IDENTIFICATION OF 10SA RNA (TMRNA) HOMOLOGS FROM THE CYANOBACTERIUM SYNECHOCOCCUS SP. STRAIN PCC6301 AND RELATED ORGANISMS

We have isolated the 1OSa RNA (tmRNA) from the unicellular cyanobacter ium Synechococcus sp. strain PCC6301. It comprises of 394 nucleotides (nt) and has 55% homology to Escherichia coli tmRNA. The cloning and s equencing of the corresponding gene have revealed that, like in many t RNA genes, the terminal CCA sequence reported in all the tmRNA species characterized so far is not encoded in the DNA. Hybridization analysi s has shown that the tmRNA gene is present as a single copy. Fairly hi gh levels of tmRNA accumulate throughout the cell cycle; however, a sl ight increase in its level is observed during late-log to stationary p hase. This suggests that tmRNA is functional not only when cells divid e actively but also when cell growth stops. (C) 1998 Elsevier Science B.V.