The non-coding RNA Ncr0700/PmgR1 is required for photomixotrophic growth and the regulation of glycogen accumulation in the cyanobacterium Synechocystis sp. PCC 6803
2016
de Porcellinis, A.J. (University of Copenhagen, Frederiksberg (Denmark). Faculty of Science, Department of Plant and Environmental Sciences, Copenhagen Plant Science Center) | Klaehn, S. | Rosgaard, L. | Kirsch, R. | Gutekunst, K. | Georg, J. | Hess, W.R. | Sakuragi, Y.
Carbohydrate metabolism is a tightly regulated process in photosynthetic organisms. In the cyanobacterium Synechocystis sp. PCC 6803, the photomixotrophic growth protein A (PmgA) is involved in the regulation of glucose and storage carbohydrate (i.e. glycogen) metabolism, while its biochemical activity and possible factors acting downstream of PmgA are unknown. Here, a genome-wide microarray analysis of a deltapmgA strain identified the expression of 36 protein-coding genes and 42 non-coding transcripts as significantly altered. From these, the non-coding RNA Ncr0700 was identified as the transcript most strongly reduced in abundance. Ncr0700 is widely conserved among cyanobacteria. In Synechocystis its expression is inversely correlated with light intensity. Similarly to a deltapmgA mutant, a deltancr0700 deletion strain showed an approximately 2-fold increase in glycogen content under photoautotrophic conditions and wild-type-like growth. Moreover, its growth was arrested by 38h after a shift to photomixotrophic conditions. Ectopic expression of Ncr0700 in deltancr0700 and deltapmgA restored the glycogen content and photomixotrophic growth to wild-type levels. These results indicate that Ncr0700 is required for photomixotrophic growth and the regulation of glycogen accumulation, and acts downstream of PmgA. Hence Ncr0700 is renamed here as PmgR1 for photomixotrophic growth RNA 1.
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