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BMC Microbiol. 2017 Dec 8;17(1):229. doi: 10.1186/s12866-017-1137-9.

6S RNA plays a role in recovery from nitrogen depletion in Synechocystis sp. PCC 6803.

Author information

1
Institute for Synthetic Microbiology, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Düsseldorf, Universitätsstrasse 1, 40225, Düsseldorf, Germany.
2
Department of Biotechnology, Beuth University of Applied Sciences, Seestr. 64, 13347, Berlin, Germany.
3
Department of Biochemistry, University of Turku, FI-20014, Turku, Finland.
4
Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Schänzlestr. 1, 79104, Freiburg, Germany.
5
Institute for Synthetic Microbiology, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Düsseldorf, Universitätsstrasse 1, 40225, Düsseldorf, Germany. ilka.axmann@hhu.de.
6
Department of Chemistry - Microbial Chemistry, Ångström and Science for Life Laboratory, Uppsala University, Box 523, SE-751 20, Uppsala, Sweden.

Abstract

BACKGROUND:

The 6S RNA is a global transcriptional riboregulator, which is exceptionally widespread among most bacterial phyla. While its role is well-characterized in some heterotrophic bacteria, we subjected a cyanobacterial homolog to functional analysis, thereby extending the scope of 6S RNA action to the special challenges of photoautotrophic lifestyles.

RESULTS:

Physiological characterization of a 6S RNA deletion strain (ΔssaA) demonstrates a delay in the recovery from nitrogen starvation. Significantly decelerated phycobilisome reassembly and glycogen degradation are accompanied with reduced photosynthetic activity compared to the wild type. Transcriptome profiling further revealed that predominantly genes encoding photosystem components, ATP synthase, phycobilisomes and ribosomal proteins were negatively affected in ΔssaA. In vivo pull-down studies of the RNA polymerase complex indicated that the presence of 6S RNA promotes the recruitment of the cyanobacterial housekeeping σ factor SigA, concurrently supporting dissociation of group 2 σ factors during recovery from nitrogen starvation.

CONCLUSIONS:

The combination of genetic, physiological and biochemical studies reveals the homologue of 6S RNA as an integral part of the cellular response of Synechocystis sp. PCC 6803 to changing nitrogen availability. According to these results, 6S RNA supports a rapid acclimation to changing nitrogen supply by accelerating the switch from group 2 σ factors SigB, SigC and SigE to SigA-dependent transcription. We therefore introduce the cyanobacterial 6S RNA as a novel candidate regulator of RNA polymerase sigma factor recruitment in Synechocystis sp. PCC 6803. Further studies on mechanistic features of the postulated interaction should shed additional light on the complexity of transcriptional regulation in cyanobacteria.

KEYWORDS:

Cyanobacteria; RNA polymerase; Small RNA; Transcriptional regulation; σ factor

PMID:
29216826
PMCID:
PMC5721685
DOI:
10.1186/s12866-017-1137-9
[Indexed for MEDLINE]
Free PMC Article

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