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Life
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Cellular and Molecular Strategies in Cyanobacterial Survival, Volume II
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Cellular and Molecular Strategies in Cyanobacterial Survival, Volume II

A special issue of Life (ISSN 2075-1729). This special issue belongs to the section "Microbiology".

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 15418

Special Issue Editors

Dr. Iris Maldener

E-Mail Website
Guest Editor
Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72074 Tübingen, Germany
Interests: microbial cell biology; filamentous cyanobacteria; heterocysts; cell–cell communication; septal junctions; akinetes; stress adaptation; ABC-transporter
Special Issues, Collections and Topics in MDPI journals
Dr. Khaled Selim

E-Mail Website
Guest Editor
Interfaculty Institute of Microbiology and Infection Medicine, Eberhard Karls Universität Tübingen, 72074 Tübingen, Germany
Interests: cell signaling in cyanobacteria; molecular mechanisms of carbon/nitrogen regulations; cyanobacterial carbon concentrating mechanisms; PII and PII-like signal transduction proteins; developmental and structural biology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

All species of cyanobacteria are capable of oxygenic photosynthesis. Despite this common mode of metabolism, they exist in different morphologies as single cells or as multicellular filaments, which may even differentiate specialized cells. Furthermore, cyanobacteria occupy almost all illuminated aquatic and terrestrial habitats, including harsh environments of deserts, oceans, and hypersaline, volcanic, and thermal biospheres. Therefore, they represent one of the quantitatively most abundant organisms on earth and can be dated back in evolution for more then 2.4 billion years. In addition to this biodiversity, many species have developed strategies to adapt to various stress conditions, including nutrient starvation, occurring in their own habitat.

In recent years, our knowledge on cyanobacterial survival strategies has increased tremendously by applying global studies like transcriptomics and proteomics, as well as advanced microscopic technics. Protein structure and function analysis have revealed the great potential of cellular and metabolic adaptation mechanisms of single cells and multicellular filaments towards environmental stress, including cell differentiation, signal transduction, formation of reserve materials, and resuscitation from dormant states, just to name a few examples.

In this Special Issue of Life, we invite researchers from all over the world to share with us the advances in our understanding of ecological, cellular, and molecular mechanisms of cyanobacterial survival. This includes original work and review articles dealing with signaling pathways, strategies of gene and protein regulation, global studies, and new discoveries related to differentiation of spore like akinetes, motile hormogonia, and nitrogen-fixing heterocysts.

Dr. Iris Maldener
Dr. Khaled Selim
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Life is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • akinete
  • carbon concentrating mechanisms
  • cell–cell communication
  • cell differentiation
  • central metabolism and C/N balance
  • cyanobacterial OMICS
  • heterocyst
  • reserve compounds
  • signal transduction
  • transcription and gene regulation

Related Special Issue

Published Papers (5 papers)

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Research

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12 pages, 2609 KiB  
Article
Changes in Envelope Structure and Cell–Cell Communication during Akinete Differentiation and Germination in Filamentous Cyanobacterium Trichormus variabilis ATCC 29413
by Ritu Garg, Manja Luckner, Jürgen Berger, Katharina Hipp, Gerhard Wanner, Karl Forchhammer and Iris Maldener
Life 2022, 12(3), 429; https://doi.org/10.3390/life12030429 - 16 Mar 2022
Cited by 1 | Viewed by 2757
Abstract
Planktonic freshwater filamentous cyanobacterium Trichormus variabilis ATCC 29413 (previously known as Anabaena variabilis) can differentiate heterocysts and akinetes to survive under different stress conditions. Whilst heterocysts enable diazotrophic growth, akinetes are spore-like resting cells that make the survival of the species possible [...] Read more.
Planktonic freshwater filamentous cyanobacterium Trichormus variabilis ATCC 29413 (previously known as Anabaena variabilis) can differentiate heterocysts and akinetes to survive under different stress conditions. Whilst heterocysts enable diazotrophic growth, akinetes are spore-like resting cells that make the survival of the species possible under adverse growth conditions. Under suitable environmental conditions, they germinate to produce new vegetative filaments. Several morphological and physiological changes occur during akinete formation and germination. Here, using scanning electron microscopy (SEM), we found that the mature akinetes had a wrinkled envelope, and the surface of the envelope smoothened as the cell size increased during germination. Thereupon, the akinete envelope ruptured to release the short emerging filament. Focused ion beam–scanning electron microscopy (FIB/SEM) tomography of immature akinetes revealed the presence of cytoplasmic granules, presumably consisting of cyanophycin or glycogen. In addition, the akinete envelope architecture of different layers, the exopolysaccharide and glycolipid layers, could be visualized. We found that this multilayered envelope helped to withstand osmotic stress and to maintain the structural integrity. Furthermore, by fluorescence recovery after photobleaching (FRAP) measurements, using the fluorescent tracer calcein, we found that intercellular communication decreased during akinete formation as compared with the vegetative cells. In contrast, freshly germinating filaments restored cell communication. Full article
(This article belongs to the Special Issue Cellular and Molecular Strategies in Cyanobacterial Survival, Volume II)
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17 pages, 3362 KiB  
Article
Roles of Close Homologues SigB and SigD in Heat and High Light Acclimation of the Cyanobacterium Synechocystis sp. PCC 6803
by Otso Turunen, Satu Koskinen, Juha Kurkela, Outi Karhuvaara, Kaisa Hakkila and Taina Tyystjärvi
Life 2022, 12(2), 162; https://doi.org/10.3390/life12020162 - 21 Jan 2022
Cited by 5 | Viewed by 2265
Abstract
Acclimation of cyanobacterium Synechocystis sp. PCC6803 to suboptimal conditions is largely dependent on adjustments of gene expression, which is highly controlled by the σ factor subunits of RNA polymerase (RNAP). The SigB and SigD σ factors are close homologues. Here we show that [...] Read more.
Acclimation of cyanobacterium Synechocystis sp. PCC6803 to suboptimal conditions is largely dependent on adjustments of gene expression, which is highly controlled by the σ factor subunits of RNA polymerase (RNAP). The SigB and SigD σ factors are close homologues. Here we show that the sigB and sigD genes are both induced in high light and heat stresses. Comparison of transcriptomes of the control strain (CS), ΔsigB, ΔsigD, ΔsigBCE (containing SigD as the only functional group 2 σ factor), and ΔsigCDE (SigB as the only functional group 2 σ factor) strains in standard, high light, and high temperature conditions revealed that the SigB and SigD factors regulate different sets of genes and SigB and SigD regulons are highly dependent on stress conditions. The SigB regulon is bigger than the SigD regulon at high temperature, whereas, in high light, the SigD regulon is bigger than the SigB regulon. Furthermore, our results show that favoring the SigB or SigD factor by deleting other group 2 σ factors does not lead to superior acclimation to high light or high temperature, indicating that all group 2 σ factors play roles in the acclimation processes. Full article
(This article belongs to the Special Issue Cellular and Molecular Strategies in Cyanobacterial Survival, Volume II)
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19 pages, 4714 KiB  
Article
Slr0320 Is Crucial for Optimal Function of Photosystem II during High Light Acclimation in Synechocystis sp. PCC 6803
by Hao Zhang, Haitao Ge, Ye Zhang, Yingchun Wang and Pengpeng Zhang
Life 2021, 11(4), 279; https://doi.org/10.3390/life11040279 - 26 Mar 2021
Cited by 2 | Viewed by 2314
Abstract
Upon exposure of photosynthetic organisms to high light (HL), several HL acclimation responses are triggered. Herein, we identified a novel gene, slr0320, critical for HL acclimation in Synechocystis sp. PCC 6803. The growth rate of the Δslr0320 mutant was similar to [...] Read more.
Upon exposure of photosynthetic organisms to high light (HL), several HL acclimation responses are triggered. Herein, we identified a novel gene, slr0320, critical for HL acclimation in Synechocystis sp. PCC 6803. The growth rate of the Δslr0320 mutant was similar to wild type (WT) under normal light (NL) but severely declined under HL. Net photosynthesis of the mutant was lower under HL, but maximum photosystem II (PSII) activity was higher under NL and HL. Immunodetection revealed the accumulation and assembly of PSII were similar between WT and the mutant. Chlorophyll fluorescence traces showed the stable fluorescence of the mutant under light was much higher. Kinetics of single flash-induced chlorophyll fluorescence increase and decay revealed the slower electron transfer from QA to QB in the mutant. These data indicate that, in the Δslr0320 mutant, the number of functional PSIIs was comparable to WT even under HL but the electron transfer between QA and QB was inefficient. Quantitative proteomics and real-time PCR revealed that expression profiles of psbL, psbH and psbI were significantly altered in the Δslr0320 mutant. Thus, Slr0320 protein plays critical roles in optimizing PSII activity during HL acclimation and is essential for PSII electron transfer from QA to QB. Full article
(This article belongs to the Special Issue Cellular and Molecular Strategies in Cyanobacterial Survival, Volume II)
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12 pages, 1580 KiB  
Communication
Fast Diffusion of the Unassembled PetC1-GFP Protein in the Cyanobacterial Thylakoid Membrane
by Radek Kaňa, Gábor Steinbach, Roman Sobotka, György Vámosi and Josef Komenda
Life 2021, 11(1), 15; https://doi.org/10.3390/life11010015 - 29 Dec 2020
Cited by 6 | Viewed by 2677
Abstract
Biological membranes were originally described as a fluid mosaic with uniform distribution of proteins and lipids. Later, heterogeneous membrane areas were found in many membrane systems including cyanobacterial thylakoids. In fact, cyanobacterial pigment–protein complexes (photosystems, phycobilisomes) form a heterogeneous mosaic of thylakoid membrane [...] Read more.
Biological membranes were originally described as a fluid mosaic with uniform distribution of proteins and lipids. Later, heterogeneous membrane areas were found in many membrane systems including cyanobacterial thylakoids. In fact, cyanobacterial pigment–protein complexes (photosystems, phycobilisomes) form a heterogeneous mosaic of thylakoid membrane microdomains (MDs) restricting protein mobility. The trafficking of membrane proteins is one of the key factors for long-term survival under stress conditions, for instance during exposure to photoinhibitory light conditions. However, the mobility of unbound ‘free’ proteins in thylakoid membrane is poorly characterized. In this work, we assessed the maximal diffusional ability of a small, unbound thylakoid membrane protein by semi-single molecule FCS (fluorescence correlation spectroscopy) method in the cyanobacterium Synechocystis sp. PCC6803. We utilized a GFP-tagged variant of the cytochrome b6f subunit PetC1 (PetC1-GFP), which was not assembled in the b6f complex due to the presence of the tag. Subsequent FCS measurements have identified a very fast diffusion of the PetC1-GFP protein in the thylakoid membrane (D = 0.14 − 2.95 µm2s−1). This means that the mobility of PetC1-GFP was comparable with that of free lipids and was 50–500 times higher in comparison to the mobility of proteins (e.g., IsiA, LHCII—light-harvesting complexes of PSII) naturally associated with larger thylakoid membrane complexes like photosystems. Our results thus demonstrate the ability of free thylakoid-membrane proteins to move very fast, revealing the crucial role of protein–protein interactions in the mobility restrictions for large thylakoid protein complexes. Full article
(This article belongs to the Special Issue Cellular and Molecular Strategies in Cyanobacterial Survival, Volume II)
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Review

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14 pages, 1379 KiB  
Review
The Circadian Clock—A Molecular Tool for Survival in Cyanobacteria
by Pyonghwa Kim, Manpreet Kaur, Hye-In Jang and Yong-Ick Kim
Life 2020, 10(12), 365; https://doi.org/10.3390/life10120365 - 20 Dec 2020
Cited by 8 | Viewed by 4487
Abstract
Cyanobacteria are photosynthetic organisms that are known to be responsible for oxygenating Earth’s early atmosphere. Having evolved to ensure optimal survival in the periodic light/dark cycle on this planet, their genetic codes are packed with various tools, including a sophisticated biological timekeeping system. [...] Read more.
Cyanobacteria are photosynthetic organisms that are known to be responsible for oxygenating Earth’s early atmosphere. Having evolved to ensure optimal survival in the periodic light/dark cycle on this planet, their genetic codes are packed with various tools, including a sophisticated biological timekeeping system. Among the cyanobacteria is Synechococcus elongatus PCC 7942, the simplest clock-harboring organism with a powerful genetic tool that enabled the identification of its intricate timekeeping mechanism. The three central oscillator proteins—KaiA, KaiB, and KaiC—drive the 24 h cyclic gene expression rhythm of cyanobacteria, and the “ticking” of the oscillator can be reconstituted inside a test tube just by mixing the three recombinant proteins with ATP and Mg2+. Along with its biochemical resilience, the post-translational rhythm of the oscillation can be reset through sensing oxidized quinone, a metabolite that becomes abundant at the onset of darkness. In addition, the output components pick up the information from the central oscillator, tuning the physiological and behavioral patterns and enabling the organism to better cope with the cyclic environmental conditions. In this review, we highlight our understanding of the cyanobacterial circadian clock and discuss how it functions as a molecular chronometer that readies the host for predictable changes in its surroundings. Full article
(This article belongs to the Special Issue Cellular and Molecular Strategies in Cyanobacterial Survival, Volume II)
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