Down-Regulation of the Alternative Sigma Factor SigJ Confers a Photoprotective Phenotype to Anabaena PCC 7120

摘要: Alternative sigma factors belonging to Group 3 are thought play an important role in the adaptation of cyanobacteria environmental challenges by altering expression genes needed for coping with such stresses. In this study, alternative factor, SigJ, was analyzed filamentous nitrogen-fixing cyanobacterium, Anabaena sp. PCC 7120 knocking down sigJ gene (alr0277) employing antisense RNA-mediated approach. absence any stress, knock-down (KD0277) or wild-type strain both grew similarly. Upon exposure high-intensity light, KD0277 showed substantially reduced bleaching its pigments, higher photosynthetic activity and consequently better survival than wild type. also enhanced accumulation two carotenoids, which were identified as myxoxanthophyll keto-myxoxanthophyll. Further, more tolerant ammonium-triggered photodamage Moreover, PSII protected against Down-regulation 7120, however, ability cope desiccation. This study demonstrates that down-regulation differentially affects tolerate environmentally relevant stresses, i.e. light