A hidden layer of genetic information - regulatory ncRNAs in a model cyanobacterium

Recent efforts to reveal the transcriptome of the cyanobacterial model organism Synechocystis PCC6803 yielded an unexpectedly complex picture, especially with respect to possible regulatory RNAs. In fact, ca. 65% of all individual transcripts in an exponentially growing Synechocystis culture are ncRNAs, while 87% of the genome is protein-coding. The high number of inter- and intragenically encoded ncRNAs, as well as asRNAs (1,2), raises the question of their biological functions and the used molecular mechanisms. Moreover, only little is known about proteins involved in RNA metabolism with the exception of Hfq (3) and several RNases. Based on the data obtained from dRNA-seq, computational predictions and initial microarrays, we developed a compact whole transcriptome microarray able to follow changes in the abundance of any of these transcripts under a variety of experimental conditions. We applied variations in growth conditions and included wild-type cells as well as a mutant for the CrhR helicase which has the ability to promote RNA helix unwinding, annealing and strand exchange (4). Here we present a global interpretation of these data and first insight into the functions of selected ncRNAs.