Identification and function of regulatory RNA in the phototrophic model organism Synechocystis sp. PCC 6803

Recent data from pro- and eukaryotic organisms show the extremely high potential of non-coding RNAs (ncRNAs) as sequence-specific regulators of gene expression, thereby mediating a plethora of cellular responses to changing environmental clues, and morphological differentiation. Here, we suggest to unravel the full set of ncRNAs in a comprehensive and systematical way by cloning and sequencing all small RNAs from the cyanobacterium Synechocystis sp. PCC 6803, paralleled by a computational prediction of ncRNA genes in intergenic regions. Synechocystis sp. PCC 6803 is the genetically best studied and easiest to handle cyanobacterium. We therefore plan to use this information to develop this organism into a true model for the analysis of regulatory RNAs in cyanobacteria by targeted knock-out mutations of genes encoding the most promising ncRNA genes and proteins with key functions in the metabolism of RNA (RNase III, RNase E, Hfq). We will put special emphasis on the functional analysis of one ncRNA, which we have identified in the course of prior work that has led to this proposal. This ncRNA is over its full length in antisense orientation to the coding region of isiA, a gene that becomes rapidly induced under iron limitation and redox stress.