title: Awakening of a Dormant Cyanobacterium from Nitrogen Chlorosis Reveals a Genetically Determined Program.
abstract: The molecular and physiological mechanisms involved in the transition of microbial cells from a resting state to the active vegetative state are critically relevant for solving problems in fields ranging from microbial ecology to infection microbiology. Cyanobacteria that cannot fix nitrogen are able to survive prolonged periods of nitrogen starvation as chlorotic cells in a dormant state. When provided with a usable nitrogen source, these cells re-green within 48 hr and return to vegetative growth. Here we investigated the resuscitation of chlorotic Synechocystis sp. PCC 6803 cells at the physiological and molecular levels with the aim of understanding the awakening process of a dormant bacterium. Almost immediately upon nitrate addition, the cells initiated a highly organized resuscitation program. In the first phase, they suppressed any residual photosynthetic activity and activated respiration to gain energy from glycogen catabolism. Concomitantly, they restored the entire translational apparatus, ATP synthesis, and nitrate assimilation. After only 12-16 hr, the cells re-activated the synthesis of the photosynthetic apparatus and prepared for metabolic re-wiring toward photosynthesis. When the cells reached full photosynthetic capacity after ∼48 hr, they resumed cell division and entered the vegetative cell cycle. An analysis of the transcriptional dynamics during the resuscitation process revealed a perfect match to the observed physiological processes, and it suggested that non-coding RNAs play a major regulatory role during the lifestyle switch in awakening cells. This genetically encoded program ensures rapid colonization of habitats in which nitrogen starvation imposes a recurring growth limitation.
authors.affiliation: Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen, Auf der Morgenstelle 28, Tübingen 72076, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Klotz
authors.affiliation: Faculty of Biology Genetics and Experimental Bioinformatics, University of Freiburg, Freiburg 79104, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Georg
authors.affiliation: Centre Algatech, Institute of Microbiology, Academy of Sciences of the Czech Republic, Třeboň 379 01, Czech Republic; Faculty of Science, University of South Bohemia, České Budějovice 370 01, Czech Republic.
authors.forename: Lenka
authors.initials: L
authors.lastname: Bučinská
authors.affiliation: Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: Faculty of Biology Genetics and Experimental Bioinformatics, University of Freiburg, Freiburg 79104, Germany.
authors.forename: Viktoria
authors.initials: V
authors.lastname: Reimann
authors.affiliation: Faculty of Biology Genetics and Experimental Bioinformatics, University of Freiburg, Freiburg 79104, Germany.
authors.forename: Witold
authors.initials: W
authors.lastname: Januszewski
authors.affiliation: Centre Algatech, Institute of Microbiology, Academy of Sciences of the Czech Republic, Třeboň 379 01, Czech Republic; Faculty of Science, University of South Bohemia, České Budějovice 370 01, Czech Republic.
authors.forename: Roman
authors.initials: R
authors.lastname: Sobotka
authors.affiliation: Institute of Microbiology, University Stuttgart, Allmandring 31, Stuttgart 70569, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Jendrossek
authors.affiliation: Faculty of Biology Genetics and Experimental Bioinformatics, University of Freiburg, Freiburg 79104, Germany.
authors.forename: Wolfgang R
authors.initials: WR
authors.lastname: Hess
authors.affiliation: Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen, Auf der Morgenstelle 28, Tübingen 72076, Germany. Electronic address: karl.forchhammer@uni-tuebingen.de.
authors.forename: Karl
authors.initials: K
authors.lastname: Forchhammer
mesh_terms: D015964:Gene Expression Regulation, Bacterial; D009584:Nitrogen / Q000378:metabolism*; D012329:RNA, Bacterial / Q000378:metabolism; D022661:RNA, Untranslated / Q000378:metabolism; D046939:Synechocystis / Q000235:genetics / Q000502:physiology*
chemical_list: D012329:RNA, Bacterial; D022661:RNA, Untranslated; D009584:Nitrogen
keywords: RuBisCO; chlorophyll biosynthesis; dormancy; glycogen; nitrate assimilation; non-coding RNA; polyhydroxybutyrate; polyploidy; starvation; synechocystis