THE GENES AROA AND TRNQ ARE LOCATED UPSTREAM OF PSBO IN THE CHROMOSOME OF SYNECHOCYSTIS 6803

We have identified the existence of two genes, trnQ and aroA, located upstream of the psbO gene in Synechocystis sp. PCC 6803. The trnQ gene encodes a glutamine-specific transfer RNA (tRNA(Gln)) and the sequenc e given is the first reported for any cyanobacterium. The gene seems t o exist as a single copy since its deletion results in non-viable muta tion. The aroA gene encodes for 5-enolpyruvylshikimate 3-phosphate syn thase and its discovery in the genome of Synechocystis 6803 is the fir st genetic evidence for the existence of the shikimate biosynthetic pa thway in cyanobacteria. Interestingly, the partial sequence shares clo se homologies with the sequences of aroA from Gram-positive bacteria.