A small internal antisense RNA (aftsH) of all3642 (ftsH) in Anabaena sp. PCC 7120

In bacteria, FtsH proteases are involved in quality maintenance of membrane proteins and cellular regulation at the level of protein stability. Among the 4 predicted ftsH genes in the cyanobacterium Anabaena sp. PCC 7120, namely alr1262, all3642, all4776 and all4936, at least the first two showed reduced transcription in specialized N2-fixing cells called heterocysts. In contrast, the transcription of a small internal antisense RNA (aftsH) of all3642 was up-regulated in heterocysts. Overexpression of the antisense RNA suppressed the expression of all3642, alr1262 and all4776. Control of promoter and modulation by antisense RNA may both contribute to gene regulation in heterocysts of filamentous cyanobacteria.