1
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Hlanze H, Mutshembele A, Reva ON. Universal Lineage-Independent Markers of Multidrug Resistance in Mycobacterium tuberculosis. Microorganisms 2024; 12:1340. [PMID: 39065108 PMCID: PMC11278869 DOI: 10.3390/microorganisms12071340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2024] [Revised: 06/23/2024] [Accepted: 06/24/2024] [Indexed: 07/28/2024] Open
Abstract
(1) Background: This study was aimed to identify universal genetic markers of multidrug resistance (MDR) in Mycobacterium tuberculosis (Mtb) and establish statistical associations among identified mutations to enhance understanding of MDR in Mtb and inform diagnostic and treatment development. (2) Methods: GWAS analysis and the statistical evaluation of identified polymorphic sites within protein-coding genes of Mtb were performed. Statistical associations between specific mutations and antibiotic resistance were established using attributable risk statistics. (3) Results: Sixty-four polymorphic sites were identified as universal markers of drug resistance, with forty-seven in PE/PPE regions and seventeen in functional genes. Mutations in genes such as cyp123, fadE36, gidB, and ethA showed significant associations with resistance to various antibiotics. Notably, mutations in cyp123 at codon position 279 were linked to resistance to ten antibiotics. The study highlighted the role of PE/PPE and PE_PGRS genes in Mtb's evolution towards a 'mutator phenotype'. The pathways of acquisition of mutations forming the epistatic landscape of MDR were discussed. (4) Conclusions: This research identifies marker mutations across the Mtb genome associated with MDR. The findings provide new insights into the molecular basis of MDR acquisition in Mtb, aiding in the development of more effective diagnostics and treatments targeting these mutations to combat MDR tuberculosis.
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Affiliation(s)
- Hleliwe Hlanze
- Centre for Bioinformatics and Computational Biology, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Hillcrest, Lynnwood Rd, Pretoria 0002, South Africa;
| | - Awelani Mutshembele
- South African Medical Research Council, TB Platform, 1 Soutpansberg Road, Private Bag X385, Pretoria 0001, South Africa;
| | - Oleg N. Reva
- Centre for Bioinformatics and Computational Biology, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Hillcrest, Lynnwood Rd, Pretoria 0002, South Africa;
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2
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Kawamoto N, Nakanishi S, Shimakawa G. Light Wavelength as a Contributory Factor of Environmental Fitness in the Cyanobacterial Circadian Clock. PLANT & CELL PHYSIOLOGY 2024; 65:798-808. [PMID: 38441328 DOI: 10.1093/pcp/pcae022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 02/23/2024] [Accepted: 02/28/2024] [Indexed: 05/31/2024]
Abstract
A circadian clock is an essential system that drives the 24-h expression rhythms for adaptation to day-night cycles. The molecular mechanism of the circadian clock has been extensively studied in cyanobacteria harboring the KaiC-based timing system. Nevertheless, our understanding of the physiological significance of the cyanobacterial circadian clock is still limited. In this study, we cultured wild-type Synechococcus elongatus PCC 7942 and circadian clock mutants in day-night cycles at different light qualities and found that the growth of the circadian clock mutants was specifically impaired during 12-h blue light/12-h dark (BD) cycles for the first time. The arrhythmic mutant kaiCAA was further analyzed by photosynthetic measurements. Compared with the wild type, the mutant exhibited decreases in the chlorophyll content, the ratio of photosystem I to II, net O2 evolution rate and efficiency of photosystem II photochemistry during BD cycles. These results indicate that the circadian clock is necessary for the growth and the maintenance of the optimum function of the photosynthetic apparatus in cyanobacteria under blue photoperiodic conditions.
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Affiliation(s)
- Naohiro Kawamoto
- Research Center for Solar Energy Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
- RNA Systems Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Wako, Saitama 351-0198, Japan
| | - Shuji Nakanishi
- Research Center for Solar Energy Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
| | - Ginga Shimakawa
- Research Center for Solar Energy Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei-Gakuin University, 1 Gakuen-Uegahara, Sanda, Hyogo 669-1330, Japan
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3
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Chavan A, Heisler J, Chang YG, Golden SS, Partch CL, LiWang A. Protocols for in vitro reconstitution of the cyanobacterial circadian clock. Biopolymers 2024; 115:e23559. [PMID: 37421636 PMCID: PMC10772220 DOI: 10.1002/bip.23559] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 05/26/2023] [Accepted: 06/16/2023] [Indexed: 07/10/2023]
Abstract
Circadian clocks are intracellular systems that orchestrate metabolic processes in anticipation of sunrise and sunset by providing an internal representation of local time. Because the ~24-h metabolic rhythms they produce are important to health across diverse life forms there is growing interest in their mechanisms. However, mechanistic studies are challenging in vivo due to the complex, that is, poorly defined, milieu of live cells. Recently, we reconstituted the intact circadian clock of cyanobacteria in vitro. It oscillates autonomously and remains phase coherent for many days with a fluorescence-based readout that enables real-time observation of individual clock proteins and promoter DNA simultaneously under defined conditions without user intervention. We found that reproducibility of the reactions required strict adherence to the quality of each recombinant clock protein purified from Escherichia coli. Here, we provide protocols for preparing in vitro clock samples so that other labs can ask questions about how changing environments, like temperature, metabolites, and protein levels are reflected in the core oscillator and propagated to regulation of transcription, providing deeper mechanistic insights into clock biology.
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Affiliation(s)
- Archana Chavan
- Center for Circadian Biology, University of California – San Diego, La Jolla, CA 92093
- School of Natural Sciences, University of California – Merced, Merced, CA 95343
| | - Joel Heisler
- Center for Circadian Biology, University of California – San Diego, La Jolla, CA 92093
- School of Natural Sciences, University of California – Merced, Merced, CA 95343
| | - Yong-Gang Chang
- Center for Circadian Biology, University of California – San Diego, La Jolla, CA 92093
- School of Natural Sciences, University of California – Merced, Merced, CA 95343
| | - Susan S. Golden
- Center for Circadian Biology, University of California – San Diego, La Jolla, CA 92093
- Department of Molecular Biology, University of California – San Diego, La Jolla, CA 92093
| | - Carrie L. Partch
- Center for Circadian Biology, University of California – San Diego, La Jolla, CA 92093
- Department of Chemistry & Biochemistry, University of California – Santa Cruz, Santa Cruz, CA 95064
| | - Andy LiWang
- Center for Circadian Biology, University of California – San Diego, La Jolla, CA 92093
- School of Natural Sciences, University of California – Merced, Merced, CA 95343
- Department of Chemistry & Biochemistry, University of California – Merced, Merced, CA 95343
- Center for Cellular and Biomolecular Machines, University of California – Merced, Merced, CA 95343
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4
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Tamaru Y, Nakanishi S, Tanaka K, Umetsu M, Nakazawa H, Sugiyama A, Ito T, Shimokawa N, Takagi M. Recent research advances on non-linear phenomena in various biosystems. J Biosci Bioeng 2023:S1389-1723(23)00107-X. [PMID: 37246137 DOI: 10.1016/j.jbiosc.2023.03.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 03/03/2023] [Accepted: 03/22/2023] [Indexed: 05/30/2023]
Abstract
All biological phenomena can be classified as open, dissipative and non-linear. Moreover, the most typical phenomena are associated with non-linearity, dissipation and openness in biological systems. In this review article, four research topics on non-linear biosystems are described to show the examples from various biological systems. First, membrane dynamics of a lipid bilayer for the cell membrane is described. Since the cell membrane separates the inside of the cell from the outside, self-organizing systems that form spatial patterns on membranes often depend on non-linear dynamics. Second, various data banks based on recent genomics analysis supply the data including vast functional proteins from many organisms and their variable species. Since the proteins existing in nature are only a very small part of the space represented by amino acid sequence, success of mutagenesis-based molecular evolution approach crucially depends on preparing a library with high enrichment of functional proteins. Third, photosynthetic organisms depend on ambient light, the regular and irregular changes of which have a significant impact on photosynthetic processes. The light-driven process proceeds through many redox couples in the cyanobacteria constituting chain of redox reactions. Forth topics focuses on a vertebrate model, the zebrafish, which can help to understand, predict and control the chaos of complex biological systems. In particular, during early developmental stages, developmental differentiation occurs dynamically from a fertilized egg to divided and mature cells. These exciting fields of complexity, chaos, and non-linear science have experienced impressive growth in recent decades. Finally, future directions for non-liner biosystems are presented.
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Affiliation(s)
- Yutaka Tamaru
- Department of Life Sciences, Graduate School of Bioresources, Mie University, 1577 Kurimamachiya, Tsu, Mie 514-8507, Japan.
| | - Shuji Nakanishi
- Research Center for Solar Energy Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Kenya Tanaka
- Research Center for Solar Energy Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Mitsuo Umetsu
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, 6-6-11 Aramakiazaaoba, Aoba, Sendai, Miyagi 980-8579, Japan
| | - Hikaru Nakazawa
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, 6-6-11 Aramakiazaaoba, Aoba, Sendai, Miyagi 980-8579, Japan
| | - Aruto Sugiyama
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, 6-6-11 Aramakiazaaoba, Aoba, Sendai, Miyagi 980-8579, Japan
| | - Tomoyuki Ito
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, 6-6-11 Aramakiazaaoba, Aoba, Sendai, Miyagi 980-8579, Japan
| | - Naofumi Shimokawa
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
| | - Masahiro Takagi
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
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Determinants of Total and Active Microbial Communities Associated with Cyanobacterial Aggregates in a Eutrophic Lake. mSystems 2023; 8:e0099222. [PMID: 36927063 PMCID: PMC10134853 DOI: 10.1128/msystems.00992-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023] Open
Abstract
Cyanobacterial aggregates (CAs) comprised of photosynthetic and phycospheric microorganisms are often the cause of cyanobacterial blooms in eutrophic freshwater lakes. Although phylogenetic diversity in CAs has been extensively studied, much less was understood about the activity status of microorganisms inside CAs and determinants of their activities. In this study, the 16S rRNA gene (rDNA)-based total communities within CAs in Lake Taihu of China were analyzed over a period of 6 months during the bloom season; the 16S rRNA-based active communities during daytime, nighttime, and under anoxic conditions were also profiled. Synchronous turnover of both cyanobacterial and phycospheric communities was observed, suggesting the presence of close interactions. The rRNA/rDNA ratio-based relative activities of individual taxa were predominantly determined by their rDNA-based relative abundances. In particular, high-abundance taxa demonstrated comparatively lower activities, whereas low-abundance taxa were generally more active. In comparison, hydrophysicochemical factors as well as diurnal and redox conditions showed much less impact on relative activities of microbial taxa within CAs. Nonetheless, total and active communities exhibited differences in community assembly processes, the former of which were almost exclusively controlled by homogeneous selection during daytime and under anoxia. Taken together, the results from this study provide novel insights into the relationships among microbial activities, community structure, and environmental conditions and highlight the importance of further exploring the regulatory mechanisms of microbial activities at the community level. IMPORTANCE Cyanobacterial aggregates are important mediators of biogeochemical cycles in eutrophic lakes during cyanobacterial blooms, yet regulators of microbial activities within them are not well understood. This study revealed rDNA-based abundances strongly affected the relative activities of microbial taxa within Microcystis aggregates, as well as trade-off effects between microbial abundances and activities. Environmental conditions further improved the levels of relative activities and affected community assembly mechanisms in phycospheric communities. The relationships among microbial activities, abundances, and environmental conditions improve our understanding of the regulatory mechanisms of microbial activities in cyanobacterial aggregates and also provide a novel clue for studying determinants of microbial activities in other ecosystems.
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6
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Bishé B, Golden SS, Golden JW. Glycogen metabolism is required for optimal cyanobacterial growth in the rapid light-dark cycle of low-Earth orbit. LIFE SCIENCES IN SPACE RESEARCH 2023; 36:18-26. [PMID: 36682825 PMCID: PMC9989776 DOI: 10.1016/j.lssr.2022.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/10/2022] [Accepted: 11/01/2022] [Indexed: 06/17/2023]
Abstract
Some designs for bioregenerative life support systems to enable human space missions incorporate cyanobacteria for removal of carbon dioxide, generation of oxygen, and treatment of wastewater, as well as providing a source of nutrition. In this study, we examined the effects of the short light-dark (LD) cycle of low-Earth orbit on algal and cyanobacterial growth, approximating conditions on the International Space Station, which orbits Earth roughly every 90 min. We found that growth of green algae was similar in both normal 12 h light:12 h dark (12 h:12 h LD) and 45':45' LD cycles. Three diverse strains of cyanobacteria were not only capable of growth in short 45':45' LD cycles, but actually grew better than in 12 h:12 h LD cycles. We showed that 45':45' LD cycles do not affect the endogenous 24 h circadian rhythms of Synechococcus elongatus. Using a dense library of randomly barcoded transposon mutants, we identified genes whose loss is detrimental for the growth of S. elongatus under 45':45' LD cycles. These include several genes involved in glycogen metabolism and the oxidative pentose phosphate pathway. Notably, 45':45' LD cycles did not affect the fitness of strains that carry mutations in the biological circadian oscillator or the clock input and output regulatory pathways. Overall, this study shows that cultures of cyanobacteria could be grown under natural sunlight of low-Earth orbit and highlights the utility of a functional genomic study in a model organism to better understand key biological processes in conditions that are relevant to space travel.
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Affiliation(s)
- Bryan Bishé
- Department of Molecular Biology, University of California San Diego, 92093 La Jolla, CA, United States
| | - Susan S Golden
- Department of Molecular Biology, University of California San Diego, 92093 La Jolla, CA, United States
| | - James W Golden
- Department of Molecular Biology, University of California San Diego, 92093 La Jolla, CA, United States.
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7
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To Die or Not to Die—Regulated Cell Death and Survival in Cyanobacteria. Microorganisms 2022; 10:microorganisms10081657. [PMID: 36014075 PMCID: PMC9415839 DOI: 10.3390/microorganisms10081657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/06/2022] [Accepted: 08/12/2022] [Indexed: 11/24/2022] Open
Abstract
Regulated cell death (RCD) is central to the development, integrity, and functionality of multicellular organisms. In the last decade, evidence has accumulated that RCD is a universal phenomenon in all life domains. Cyanobacteria are of specific interest due to their importance in aquatic and terrestrial habitats and their role as primary producers in global nutrient cycling. Current knowledge on cyanobacterial RCD is based mainly on biochemical and morphological observations, often by methods directly transferred from vertebrate research and with limited understanding of the molecular genetic basis. However, the metabolism of different cyanobacteria groups relies on photosynthesis and nitrogen fixation, whereas mitochondria are the central executioner of cell death in vertebrates. Moreover, cyanobacteria chosen as biological models in RCD studies are mainly colonial or filamentous multicellular organisms. On the other hand, unicellular cyanobacteria have regulated programs of cellular survival (RCS) such as chlorosis and post-chlorosis resuscitation. The co-existence of different genetically regulated programs in cyanobacterial populations may have been a top engine in life diversification. Development of cyanobacteria-specific methods for identification and characterization of RCD and wider use of single-cell analysis combined with intelligent image-based cell sorting and metagenomics would shed more light on the underlying molecular mechanisms and help us to address the complex colonial interactions during these events. In this review, we focus on the functional implications of RCD in cyanobacterial communities.
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8
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Abstract
Strains of the freshwater cyanobacterium Synechococcus elongatus were first isolated approximately 60 years ago, and PCC 7942 is well established as a model for photosynthesis, circadian biology, and biotechnology research. The recent isolation of UTEX 3055 and subsequent discoveries in biofilm and phototaxis phenotypes suggest that lab strains of S. elongatus are highly domesticated. We performed a comprehensive genome comparison among the available genomes of S. elongatus and sequenced two additional laboratory strains to trace the loss of native phenotypes from the standard lab strains and determine the genetic basis of useful phenotypes. The genome comparison analysis provides a pangenome description of S. elongatus, as well as correction of extensive errors in the published sequence for the type strain PCC 6301. The comparison of gene sets and single nucleotide polymorphisms (SNPs) among strains clarifies strain isolation histories and, together with large-scale genome differences, supports a hypothesis of laboratory domestication. Prophage genes in laboratory strains, but not UTEX 3055, affect pigmentation, while unique genes in UTEX 3055 are necessary for phototaxis. The genomic differences identified in this study include previously reported SNPs that are, in reality, sequencing errors, as well as SNPs and genome differences that have phenotypic consequences. One SNP in the circadian response regulator rpaA that has caused confusion is clarified here as belonging to an aberrant clone of PCC 7942, used for the published genome sequence, that has confounded the interpretation of circadian fitness research.
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9
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Ibrahim IM, Rowden SJL, Cramer WA, Howe CJ, Puthiyaveetil S. Thiol redox switches regulate the oligomeric state of cyanobacterial Rre1, RpaA, and RpaB response regulators. FEBS Lett 2022; 596:1533-1543. [PMID: 35353903 PMCID: PMC9321951 DOI: 10.1002/1873-3468.14340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/11/2022] [Accepted: 03/16/2022] [Indexed: 11/18/2022]
Abstract
Cyanobacteria employ two‐component sensor‐response regulator systems to monitor and respond to environmental challenges. The response regulators RpaA, RpaB, Rre1 and RppA are integral to circadian clock function and abiotic stress acclimation in cyanobacteria. RpaA, RpaB and Rre1 are known to interact with ferredoxin or thioredoxin, raising the possibility of their thiol regulation. Here, we report that Synechocystis sp. PCC 6803 Rre1, RpaA and RpaB exist as higher‐order oligomers under oxidising conditions and that reduced thioredoxin A converts them to monomers. We further show that these response regulators contain redox‐responsive cysteine residues with an Em7 around −300 mV. These findings suggest a direct thiol modulation of the activity of these response regulators, independent of their cognate sensor kinases.
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Affiliation(s)
- Iskander M Ibrahim
- Department of Biochemistry and Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA
| | - Stephen J L Rowden
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - William A Cramer
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Christopher J Howe
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Sujith Puthiyaveetil
- Department of Biochemistry and Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA
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10
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Chele KH, Steenkamp P, Piater LA, Dubery IA, Huyser J, Tugizimana F. A Global Metabolic Map Defines the Effects of a Si-Based Biostimulant on Tomato Plants under Normal and Saline Conditions. Metabolites 2021; 11:metabo11120820. [PMID: 34940578 PMCID: PMC8709197 DOI: 10.3390/metabo11120820] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 11/10/2021] [Accepted: 11/13/2021] [Indexed: 01/19/2023] Open
Abstract
The ongoing unpredictability of climate changes is exponentially exerting a negative impact on crop production, further aggravating detrimental abiotic stress effects. Several research studies have been focused on the genetic modification of crop plants to achieve more crop resilience against such stress factors; however, there has been a paradigm shift in modern agriculture focusing on more organic, eco-friendly and long-lasting systems to improve crop yield. As such, extensive research into the use of microbial and nonmicrobial biostimulants has been at the core of agricultural studies to improve crop growth and development, as well as to attain tolerance against several biotic and abiotic stresses. However, the molecular mechanisms underlying the biostimulant activity remain enigmatic. Thus, this study is a liquid chromatography-mass spectrometry (LC-MS)-based untargeted metabolomics approach to unravel the hypothetical biochemical framework underlying effects of a nonmicrobial biostimulant (a silicon-based formulation) on tomato plants (Solanum lycopersium) under salinity stress conditions. This metabolomics study postulates that Si-based biostimulants could alleviate salinity stress in tomato plants through modulation of the primary metabolism involving changes in the tricarboxylic acid cycle, fatty acid and numerous amino acid biosynthesis pathways, with further reprogramming of several secondary metabolism pathways such as the phenylpropanoid pathway, flavonoid biosynthesis pathways including flavone and flavanol biosynthesis. Thus, the postulated hypothetical framework, describing biostimulant-induced metabolic events in tomato plants, provides actionable knowledge necessary for industries and farmers to, confidently and innovatively, explore, design, and fully implement Si-based formulations and strategies into agronomic practices for sustainable agriculture and food production.
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Affiliation(s)
- Kekeletso H. Chele
- Department of Biochemistry, University of Johannesburg, Auckland Park, Johannesburg 2006, South Africa; (K.H.C.); (P.S.); (L.A.P.); (I.A.D.)
| | - Paul Steenkamp
- Department of Biochemistry, University of Johannesburg, Auckland Park, Johannesburg 2006, South Africa; (K.H.C.); (P.S.); (L.A.P.); (I.A.D.)
| | - Lizelle A. Piater
- Department of Biochemistry, University of Johannesburg, Auckland Park, Johannesburg 2006, South Africa; (K.H.C.); (P.S.); (L.A.P.); (I.A.D.)
| | - Ian A. Dubery
- Department of Biochemistry, University of Johannesburg, Auckland Park, Johannesburg 2006, South Africa; (K.H.C.); (P.S.); (L.A.P.); (I.A.D.)
| | - Johan Huyser
- International Research and Development Division, Omnia Group, Ltd., Johannesburg 2021, South Africa;
| | - Fidele Tugizimana
- Department of Biochemistry, University of Johannesburg, Auckland Park, Johannesburg 2006, South Africa; (K.H.C.); (P.S.); (L.A.P.); (I.A.D.)
- International Research and Development Division, Omnia Group, Ltd., Johannesburg 2021, South Africa;
- Correspondence: ; Tel.: +27-011-559-7784
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11
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Kim P, Thati N, Peshori S, Jang HI, Kim YI. Shift in Conformational Equilibrium Underlies the Oscillatory Phosphoryl Transfer Reaction in the Circadian Clock. Life (Basel) 2021; 11:life11101058. [PMID: 34685430 PMCID: PMC8538168 DOI: 10.3390/life11101058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/01/2021] [Accepted: 10/05/2021] [Indexed: 11/26/2022] Open
Abstract
Oscillatory phosphorylation/dephosphorylation can be commonly found in a biological system as a means of signal transduction though its pivotal presence in the workings of circadian clocks has drawn significant interest: for example in a significant portion of the physiology of Synechococcus elongatus PCC 7942. The biological oscillatory reaction in the cyanobacterial circadian clock can be visualized through its reconstitution in a test tube by mixing three proteins—KaiA, KaiB and KaiC—with adenosine triphosphate and magnesium ions. Surprisingly, the oscillatory phosphorylation/dephosphorylation of the hexameric KaiC takes place spontaneously and almost indefinitely in a test tube as long as ATP is present. This autonomous post-translational modification is tightly regulated by the conformational change of the C-terminal peptide of KaiC called the “A-loop” between the exposed and the buried states, a process induced by the time-course binding events of KaiA and KaiB to KaiC. There are three putative hydrogen-bond forming residues of the A-loop that are important for stabilizing its buried conformation. Substituting the residues with alanine enabled us to observe KaiB’s role in dephosphorylating hyperphosphorylated KaiC, independent of KaiA’s effect. We found a novel role of KaiB that its binding to KaiC induces the A-loop toward its buried conformation, which in turn activates the autodephosphorylation of KaiC. In addition to its traditional role of sequestering KaiA, KaiB’s binding contributes to the robustness of cyclic KaiC phosphorylation by inhibiting it during the dephosphorylation phase, effectively shifting the equilibrium toward the correct phase of the clock.
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Affiliation(s)
- Pyonghwa Kim
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102, USA;
| | - Neha Thati
- Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA; (N.T.); (S.P.)
| | - Shreya Peshori
- Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA; (N.T.); (S.P.)
| | - Hye-In Jang
- School of Cosmetic Science and Beauty Biotechnology, Semyung University, Jecheon 27136, Korea
- Correspondence: (H.-I.J.); (Y.-I.K.)
| | - Yong-Ick Kim
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102, USA;
- Institute for Brain and Neuroscience Research, New Jersey Institute of Technology, Newark, NJ 07102, USA
- Correspondence: (H.-I.J.); (Y.-I.K.)
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12
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Hasegawa H, Tsurumaki T, Imamura S, Sonoike K, Tanaka K. The circadian rhythm regulator RpaA modulates photosynthetic electron transport and alters the preferable temperature range for growth in a cyanobacterium. FEBS Lett 2021; 595:1480-1492. [PMID: 33728661 DOI: 10.1002/1873-3468.14075] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 03/07/2021] [Accepted: 03/09/2021] [Indexed: 11/07/2022]
Abstract
Cyanobacterial strains can grow within a specific temperature range that approximately corresponds to their natural habitat. However, how the preferable temperature range for growth (PTRG) is determined at the molecular level remains unclear. In this study, we detected a PTRG upshift in a mutant strain of Synechococcus elongatus PCC 7942 lacking the circadian rhythm regulator RpaA. Subsequent analyses revealed that RpaA decreases the electron transport from photosystem I to NADPH. The change in electron transport likely inhibits H2 O2 generation under high-temperature conditions and contributes to the observed PTRG upshift in rpaA-deficient cells. The importance of the effects of the circadian rhythm regulator on the PTRG is discussed.
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Affiliation(s)
- Hazuki Hasegawa
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Tatsuhiro Tsurumaki
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Sousuke Imamura
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Kintake Sonoike
- Faculty of Education and Integrated Arts and Sciences, Waseda University, Tokyo, Japan
| | - Kan Tanaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
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13
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Alamoudi AA. Why do cancer cells break from host circadian rhythm? Insights from unicellular organisms. Bioessays 2021; 43:e2000205. [PMID: 33533033 DOI: 10.1002/bies.202000205] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 11/30/2020] [Accepted: 12/17/2020] [Indexed: 12/12/2022]
Abstract
It is not clear why cancer cells choose to disrupt their circadian clock rhythms, and whether such disruption governs a selective fitness and a survival advantage. In this review, I focus on understanding the impacts of clock gene disruption on a simpler model, such as the unicellular cyanobacterium, in order to explain how cancer cells may alter the circadian rhythm to reprogram their metabolism based on their needs and status. It appears to be that the activation of the oxidative pentose phosphate pathway (OPPP) and production of NADPH, the preferred molecule for detoxification of reactive oxygen species, is a critical process for night survival in unicellular organisms. The circadian clock acts as a gatekeeper that controls how the organism will utilize its sugar, shifting sugar influx between glycolysis and OPPP. The circadian clock can thus act as a gatekeeper between an anabolic, proliferative mode and a homeostatic, survival mode.
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Affiliation(s)
- Aliaa A Alamoudi
- Clinical Biochemistry Department, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia.,Stem Cell Unit, King Fahad Medical Research Center, Jeddah, Saudi Arabia
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14
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Scheurer NM, Rajarathinam Y, Timm S, Köbler C, Kopka J, Hagemann M, Wilde A. Homologs of Circadian Clock Proteins Impact the Metabolic Switch Between Light and Dark Growth in the Cyanobacterium Synechocystis sp. PCC 6803. FRONTIERS IN PLANT SCIENCE 2021; 12:675227. [PMID: 34239525 PMCID: PMC8258377 DOI: 10.3389/fpls.2021.675227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 05/26/2021] [Indexed: 05/06/2023]
Abstract
The putative circadian clock system of the facultative heterotrophic cyanobacterial strain Synechocystis sp. PCC 6803 comprises the following three Kai-based systems: a KaiABC-based potential oscillator that is linked to the SasA-RpaA two-component output pathway and two additional KaiBC systems without a cognate KaiA component. Mutants lacking the genes encoding the KaiAB1C1 components or the response regulator RpaA show reduced growth in light/dark cycles and do not show heterotrophic growth in the dark. In the present study, the effect of these mutations on central metabolism was analyzed by targeted and non-targeted metabolite profiling. The strongest metabolic changes were observed in the dark in ΔrpaA and, to a lesser extent, in the ΔkaiAB1C1 mutant. These observations included the overaccumulation of 2-phosphoglycolate, which correlated with the overaccumulation of the RbcL subunit in the mutants, and taken together, these data suggest enhanced RubisCO activity in the dark. The imbalanced carbon metabolism in the ΔrpaA mutant extended to the pyruvate family of amino acids, which showed increased accumulation in the dark. Hence, the deletion of the response regulator rpaA had a more pronounced effect on metabolism than the deletion of the kai genes. The larger impact of the rpaA mutation is in agreement with previous transcriptomic analyses and likely relates to a KaiAB1C1-independent function as a transcription factor. Collectively, our data demonstrate an important role of homologs of clock proteins in Synechocystis for balanced carbon and nitrogen metabolism during light-to-dark transitions.
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Affiliation(s)
- Nina M. Scheurer
- Institute of Biology III, University of Freiburg, Freiburg, Germany
| | - Yogeswari Rajarathinam
- Applied Metabolome Analysis, Department of Molecular Physiology, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Stefan Timm
- Department of Plant Physiology, University of Rostock, Rostock, Germany
| | - Christin Köbler
- Institute of Biology III, University of Freiburg, Freiburg, Germany
| | - Joachim Kopka
- Applied Metabolome Analysis, Department of Molecular Physiology, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Martin Hagemann
- Department of Plant Physiology, University of Rostock, Rostock, Germany
| | - Annegret Wilde
- Institute of Biology III, University of Freiburg, Freiburg, Germany
- *Correspondence: Annegret Wilde
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15
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Kim P, Kaur M, Jang HI, Kim YI. The Circadian Clock-A Molecular Tool for Survival in Cyanobacteria. Life (Basel) 2020; 10:life10120365. [PMID: 33419320 PMCID: PMC7766417 DOI: 10.3390/life10120365] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 12/16/2020] [Accepted: 12/17/2020] [Indexed: 11/16/2022] Open
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. 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.
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Affiliation(s)
- Pyonghwa Kim
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102, USA; (P.K.); (M.K.)
| | - Manpreet Kaur
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102, USA; (P.K.); (M.K.)
| | - Hye-In Jang
- School of Cosmetic Science and Beauty Biotechnology, Semyung University, Jecheon 27136, Korea
- Correspondence: (H.-I.J.); (Y.-I.K.)
| | - Yong-Ick Kim
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102, USA; (P.K.); (M.K.)
- Institute for Brain and Neuroscience Research, New Jersey Institute of Technology, Newark, NJ 07102, USA
- Correspondence: (H.-I.J.); (Y.-I.K.)
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16
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The Many Roles of the Bacterial Second Messenger Cyclic di-AMP in Adapting to Stress Cues. J Bacteriol 2020; 203:JB.00348-20. [PMID: 32839175 DOI: 10.1128/jb.00348-20] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Bacteria respond to changes in environmental conditions through adaptation to external cues. Frequently, bacteria employ nucleotide signaling molecules to mediate a specific, rapid response. Cyclic di-AMP (c-di-AMP) was recently discovered to be a bacterial second messenger that is essential for viability in many species. In this review, we highlight recent work that has described the roles of c-di-AMP in bacterial responses to various stress conditions. These studies show that depending on the lifestyle and environmental niche of the bacterial species, the c-di-AMP signaling network results in diverse outcomes, such as regulating osmolyte transport, controlling plant attachment, or providing a checkpoint for spore formation. c-di-AMP achieves this signaling specificity through expression of different classes of synthesis and catabolic enzymes as well as receptor proteins and RNAs, which will be summarized.
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17
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Time-of-day-dependent responses of cyanobacterial cellular viability against oxidative stress. Sci Rep 2020; 10:20029. [PMID: 33208874 PMCID: PMC7676254 DOI: 10.1038/s41598-020-77141-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 11/03/2020] [Indexed: 01/05/2023] Open
Abstract
As an adaptation to periodic fluctuations of environmental light, photosynthetic organisms have evolved a circadian clock. Control by the circadian clock of many cellular physiological functions, including antioxidant enzymes, metabolism and the cell cycle, has attracted attention in the context of oxidative stress tolerance. However, since each physiological function works in an integrated manner to deal with oxidative stress, whether or not cell responses to oxidative stress are under circadian control remains an open question. In fact, circadian rhythms of oxidative stress tolerance have not yet been experimentally demonstrated. In the present work, we applied an assay using methyl viologen (MV), which generates reactive oxygen species (ROS) under light irradiation, and experimentally verified the circadian rhythms of oxidative stress tolerance in photosynthetic cells of the cyanobacterium Synechococcus elongatus PCC 7942, a standard model species for investigation of the circadian clock. Here, we report that ROS generated by MV treatment causes damage to stroma components and not to the photosynthetic electron transportation chain, leading to reduced cell viability. The degree of decrease in cell viability was dependent on the subjective time at which oxidative stress was applied. Thus, oxidative stress tolerance was shown to exhibit circadian rhythms. In addition, the rhythmic pattern of oxidative stress tolerance disappeared in mutant cells lacking the essential clock genes. Notably, ROS levels changed periodically, independent of the MV treatment. Thus, we demonstrate for the first time that in cyanobacterial cells, oxidative stress tolerance shows circadian oscillation.
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18
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Ch R, Chevallier O, Elliott CT. Metabolomics reveal circadian control of cellular metabolism. Trends Analyt Chem 2020. [DOI: 10.1016/j.trac.2020.115986] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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19
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Pattanayak GK, Liao Y, Wallace EWJ, Budnik B, Drummond DA, Rust MJ. Daily Cycles of Reversible Protein Condensation in Cyanobacteria. Cell Rep 2020; 32:108032. [PMID: 32814039 PMCID: PMC10005845 DOI: 10.1016/j.celrep.2020.108032] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 07/08/2020] [Accepted: 07/23/2020] [Indexed: 12/21/2022] Open
Abstract
An emerging principle of cell biology is the regulated conversion of macromolecules between soluble and condensed states. To screen for such regulation of the cyanobacterial proteome, we use quantitative mass spectrometry to identify proteins that change solubility during the day-night cycle. We find a set of night-insoluble proteins that includes many enzymes in essential metabolic pathways. Using time-lapse microscopy and isotope labeling, we show that these proteins reversibly transition between punctate structures at night and a soluble state during the day without substantial degradation. We find that the cyanobacterial circadian clock regulates the kinetics of puncta formation during the night and that the appearance of puncta indicates the metabolic status of the cell. Reversible condensation of specific enzymes is thus a regulated response to the day-night cycle and may reflect a general bacterial strategy used in fluctuating growth conditions.
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Affiliation(s)
- Gopal K Pattanayak
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Yi Liao
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Edward W J Wallace
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Bogdan Budnik
- Mass Spectrometry and Proteomics Resource Laboratory, FAS Division of Science, Harvard University, Cambridge, MA 02138, USA
| | - D Allan Drummond
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Michael J Rust
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA; Department of Physics, University of Chicago, Chicago, IL 60637, USA.
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20
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Diallo AB, Coiffard B, Leone M, Mezouar S, Mege JL. For Whom the Clock Ticks: Clinical Chronobiology for Infectious Diseases. Front Immunol 2020; 11:1457. [PMID: 32733482 PMCID: PMC7363845 DOI: 10.3389/fimmu.2020.01457] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 06/04/2020] [Indexed: 12/20/2022] Open
Abstract
The host defense against pathogens varies among individuals. Among the factors influencing host response, those associated with circadian disruptions are emerging. These latter depend on molecular clocks, which control the two partners of host defense: microbes and immune system. There is some evidence that infections are closely related to circadian rhythms in terms of susceptibility, clinical presentation and severity. In this review, we overview what is known about circadian rhythms in infectious diseases and update the knowledge about circadian rhythms in immune system, pathogens and vectors. This heuristic approach opens a new fascinating field of time-based personalized treatment of infected patients.
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Affiliation(s)
- Aïssatou Bailo Diallo
- Aix-Marseille Univ, MEPHI, IRD, AP-HM, Marseille, France.,IHU-Méditerranée Infection, Marseille, France
| | - Benjamin Coiffard
- Aix-Marseille Univ, MEPHI, IRD, AP-HM, Marseille, France.,IHU-Méditerranée Infection, Marseille, France.,Aix-Marseille Univ, AP-HM, Hôpital Nord, Médecine Intensive-Réanimation, Marseille, France
| | - Marc Leone
- Aix-Marseille Univ, MEPHI, IRD, AP-HM, Marseille, France.,IHU-Méditerranée Infection, Marseille, France.,Aix-Marseille Univ, AP-HM, CHU Hôpital Nord, Service d'Anesthésie et de Réanimation, Marseille, France
| | - Soraya Mezouar
- Aix-Marseille Univ, MEPHI, IRD, AP-HM, Marseille, France.,IHU-Méditerranée Infection, Marseille, France
| | - Jean-Louis Mege
- Aix-Marseille Univ, MEPHI, IRD, AP-HM, Marseille, France.,IHU-Méditerranée Infection, Marseille, France.,AP-HM, UF Immunologie, Marseille, France
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21
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Philippou K, Davis AM, Davis SJ, Sánchez-Villarreal A. Chemical Perturbation of Chloroplast-Related Processes Affects Circadian Rhythms of Gene Expression in Arabidopsis: Salicylic Acid Application Can Entrain the Clock. Front Physiol 2020; 11:429. [PMID: 32625102 PMCID: PMC7314985 DOI: 10.3389/fphys.2020.00429] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 04/08/2020] [Indexed: 11/26/2022] Open
Abstract
The plant circadian system reciprocally interacts with metabolic processes. To investigate entrainment features in metabolic–circadian interactions, we used a chemical approach to perturb metabolism and monitored the pace of nuclear-driven circadian oscillations. We found that chemicals that alter chloroplast-related functions modified the circadian rhythms. Both vitamin C and paraquat altered the circadian period in a light-quality-dependent manner, whereas rifampicin lengthened the circadian period under darkness. Salicylic acid (SA) increased oscillatory robustness and shortened the period. The latter was attenuated by sucrose addition and was also gated, taking place during the first 3 h of the subjective day. Furthermore, the effect of SA on period length was dependent on light quality and genotype. Period lengthening or shortening by these chemicals was correlated to their inferred impact on photosynthetic electron transport activity and the redox state of plastoquinone (PQ). Based on these data and on previous publications on circadian effects that alter the redox state of PQ, we propose that the photosynthetic electron transport and the redox state of PQ participate in circadian periodicity. Moreover, coupling between chloroplast-derived signals and nuclear oscillations, as observed in our chemical and genetic assays, produces traits that are predicted by previous models. SA signaling or a related process forms a rhythmic input loop to drive robust nuclear oscillations in the context predicted by the zeitnehmer model, which was previously developed for Neurospora. We further discuss the possibility that electron transport chains (ETCs) are part of this mechanism.
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Affiliation(s)
- Koumis Philippou
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Amanda M Davis
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany.,Department of Biology, University of York, York, United Kingdom
| | - Seth J Davis
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany.,Department of Biology, University of York, York, United Kingdom.,Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng, China
| | - Alfredo Sánchez-Villarreal
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany
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22
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The circadian clock and darkness control natural competence in cyanobacteria. Nat Commun 2020; 11:1688. [PMID: 32245943 PMCID: PMC7125226 DOI: 10.1038/s41467-020-15384-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 03/05/2020] [Indexed: 11/15/2022] Open
Abstract
The cyanobacterium Synechococcus elongatus is a model organism for the study of circadian rhythms. It is naturally competent for transformation—that is, it takes up DNA from the environment, but the underlying mechanisms are unclear. Here, we use a genome-wide screen to identify genes required for natural transformation in S. elongatus, including genes encoding a conserved Type IV pilus, genes known to be associated with competence in other bacteria, and others. Pilus biogenesis occurs daily in the morning, while natural transformation is maximal when the onset of darkness coincides with the dusk circadian peak. Thus, the competence state in cyanobacteria is regulated by the circadian clock and can adapt to seasonal changes of day length. The cyanobacterium Synechococcus elongatus is a model organism for the study of circadian rhythms, and is naturally competent for transformation. Here, Taton et al. identify genes required for natural transformation in this organism, and show that the coincidence of circadian dusk and darkness regulates the competence state in different day lengths.
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23
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Synechocystis KaiC3 Displays Temperature- and KaiB-Dependent ATPase Activity and Is Important for Growth in Darkness. J Bacteriol 2020; 202:JB.00478-19. [PMID: 31767776 PMCID: PMC6989803 DOI: 10.1128/jb.00478-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 11/17/2019] [Indexed: 02/05/2023] Open
Abstract
Cyanobacteria form a heterogeneous bacterial group with diverse lifestyles, acclimation strategies, and differences in the presence of circadian clock proteins. In Synechococcus elongatus PCC 7942, a unique posttranslational KaiABC oscillator drives circadian rhythms. ATPase activity of KaiC correlates with the period of the clock and mediates temperature compensation. Synechocystis sp. strain PCC 6803 expresses additional Kai proteins, of which KaiB3 and KaiC3 proteins were suggested to fine-tune the standard KaiAB1C1 oscillator. In the present study, we therefore characterized the enzymatic activity of KaiC3 as a representative of nonstandard KaiC homologs in vitro KaiC3 displayed ATPase activity lower than that of the Synechococcus elongatus PCC 7942 KaiC protein. ATP hydrolysis was temperature dependent. Hence, KaiC3 is missing a defining feature of the model cyanobacterial circadian oscillator. Yeast two-hybrid analysis showed that KaiC3 interacts with KaiB3, KaiC1, and KaiB1. Further, KaiB3 and KaiB1 reduced in vitro ATP hydrolysis by KaiC3. Spot assays showed that chemoheterotrophic growth in constant darkness is completely abolished after deletion of ΔkaiAB1C1 and reduced in the absence of kaiC3 We therefore suggest a role for adaptation to darkness for KaiC3 as well as a cross talk between the KaiC1- and KaiC3-based systems.IMPORTANCE The circadian clock influences the cyanobacterial metabolism, and deeper understanding of its regulation will be important for metabolic optimizations in the context of industrial applications. Due to the heterogeneity of cyanobacteria, characterization of clock systems in organisms apart from the circadian model Synechococcus elongatus PCC 7942 is required. Synechocystis sp. strain PCC 6803 represents a major cyanobacterial model organism and harbors phylogenetically diverged homologs of the clock proteins, which are present in various other noncyanobacterial prokaryotes. By our in vitro studies we unravel the interplay of the multiple Synechocystis Kai proteins and characterize enzymatic activities of the nonstandard clock homolog KaiC3. We show that the deletion of kaiC3 affects growth in constant darkness, suggesting its involvement in the regulation of nonphotosynthetic metabolic pathways.
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24
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Shinde S, Zhang X, Singapuri SP, Kalra I, Liu X, Morgan-Kiss RM, Wang X. Glycogen Metabolism Supports Photosynthesis Start through the Oxidative Pentose Phosphate Pathway in Cyanobacteria. PLANT PHYSIOLOGY 2020; 182:507-517. [PMID: 31649110 PMCID: PMC6945877 DOI: 10.1104/pp.19.01184] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 10/17/2019] [Indexed: 06/07/2023]
Abstract
Cyanobacteria experience drastic changes in their carbon metabolism under daily light/dark cycles. During the day, the Calvin-Benson cycle fixes CO2 and diverts excess carbon into glycogen storage. At night, glycogen is degraded to support cellular respiration. The dark/light transition represents a universal environmental stress for cyanobacteria and other photosynthetic lifeforms. Recent studies revealed the essential genetic background necessary for the fitness of cyanobacteria during diurnal growth. However, the metabolic processes underlying the dark/light transition are not well understood. In this study, we observed that glycogen metabolism supports photosynthesis in the cyanobacterium Synechococcus elongatus PCC 7942 when photosynthesis reactions start upon light exposure. Compared with the wild type, the glycogen mutant ∆glgC showed a reduced photosynthetic efficiency and a slower P700+ rereduction rate when photosynthesis starts. Proteomic analyses indicated that glycogen is degraded through the oxidative pentose phosphate (OPP) pathway during the dark/light transition. We confirmed that the OPP pathway is essential for the initiation of photosynthesis and further showed that glycogen degradation through the OPP pathway contributes to the activation of key Calvin-Benson cycle enzymes by modulating NADPH levels. This strategy stimulates photosynthesis in cyanobacteria following dark respiration and stabilizes the Calvin-Benson cycle under fluctuating environmental conditions, thereby offering evolutionary advantages for photosynthetic organisms using the Calvin-Benson cycle for carbon fixation.
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Affiliation(s)
- Shrameeta Shinde
- Department of Microbiology, Miami University, Oxford, Ohio 45056
| | - Xiaohui Zhang
- Department of Microbiology, Miami University, Oxford, Ohio 45056
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300354, China
| | | | - Isha Kalra
- Department of Microbiology, Miami University, Oxford, Ohio 45056
| | - Xianhua Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300354, China
| | | | - Xin Wang
- Department of Microbiology, Miami University, Oxford, Ohio 45056
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25
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Babele PK, Kumar J, Chaturvedi V. Proteomic De-Regulation in Cyanobacteria in Response to Abiotic Stresses. Front Microbiol 2019; 10:1315. [PMID: 31263458 PMCID: PMC6584798 DOI: 10.3389/fmicb.2019.01315] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 05/27/2019] [Indexed: 11/13/2022] Open
Abstract
Cyanobacteria are oxygenic photoautotrophs, exhibiting a cosmopolitan distribution in almost all possible environments and are significantly responsible for half of the global net primary productivity. They are well adapted to the diverse environments including harsh conditions by evolving a range of fascinating repertoires of unique biomolecules and secondary metabolites to support their growth and survival. These phototrophs are proved as excellent models for unraveling the mysteries of basic biochemical and physiological processes taking place in higher plants. Several known species of cyanobacteria have tremendous biotechnological applications in diverse fields such as biofuels, biopolymers, secondary metabolites and much more. Due to their potential biotechnological and commercial applications in various fields, there is an imperative need to engineer robust cyanobacteria in such a way that they can tolerate and acclimatize to ever-changing environmental conditions. Adaptations to stress are mainly governed by a precise gene regulation pathways resulting in the expression of novel protein/enzymes and metabolites. Despite the demand, till date few proteins/enzymes have been identified which play a potential role in improving tolerance against abiotic stresses. Therefore, it is utmost important to study environmental stress responses related to post-genomic investigations, including proteomic changes employing advanced proteomics, synthetic and structural biology workflows. In this respect, the study of stress proteomics offers exclusive advantages to scientists working on these aspects. Advancements on these fields could be helpful in dissecting, characterization and manipulation of physiological and metabolic systems of cyanobacteria to understand the stress induced proteomic responses. Till date, it remains ambiguous how cyanobacteria perceive changes in the ambient environment that lead to the stress-induced proteins thus metabolic deregulation. This review briefly describes the current major findings in the fields of proteome research on the cyanobacteria under various abiotic stresses. These findings may improve and advance the information on the role of different class of proteins associated with the mechanism(s) of stress mitigation in cyanobacteria under harsh environmental conditions.
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Affiliation(s)
- Piyoosh Kumar Babele
- Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, India
- School of Biotechnology, Institute of Science, Banaras Hindu University, Varanasi, India
| | - Jay Kumar
- School of Biotechnology, Institute of Science, Banaras Hindu University, Varanasi, India
| | - Venkatesh Chaturvedi
- School of Biotechnology, Institute of Science, Banaras Hindu University, Varanasi, India
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26
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Transcription in cyanobacteria: a distinctive machinery and putative mechanisms. Biochem Soc Trans 2019; 47:679-689. [DOI: 10.1042/bst20180508] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 01/11/2019] [Accepted: 02/04/2019] [Indexed: 02/03/2023]
Abstract
Abstract
Transcription in cyanobacteria involves several fascinating features. Cyanobacteria comprise one of the very few groups in which no proofreading factors (Gre homologues) have been identified. Gre factors increase the efficiency of RNA cleavage, therefore helping to maintain the fidelity of the RNA transcript and assist in the resolution of stalled RNAPs to prevent genome damage. The vast majority of bacterial species encode at least one of these highly conserved factors and so their absence in cyanobacteria is intriguing. Additionally, the largest subunit of bacterial RNAP has undergone a split in cyanobacteria to form two subunits and the SI3 insertion within the integral trigger loop element is roughly 3.5 times larger than in Escherichia coli. The Rho termination factor also appears to be absent, leaving cyanobacteria to rely solely on an intrinsic termination mechanism. Furthermore, cyanobacteria must be able to respond to environment signals such as light intensity and tightly synchronise gene expression and other cell activities to a circadian rhythm.
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27
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Welkie DG, Rubin BE, Diamond S, Hood RD, Savage DF, Golden SS. A Hard Day's Night: Cyanobacteria in Diel Cycles. Trends Microbiol 2019; 27:231-242. [PMID: 30527541 PMCID: PMC6377297 DOI: 10.1016/j.tim.2018.11.002] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 11/01/2018] [Accepted: 11/02/2018] [Indexed: 12/31/2022]
Abstract
Cyanobacteria are photosynthetic prokaryotes that are influential in global geochemistry and are promising candidates for industrial applications. Because the livelihood of cyanobacteria is directly dependent upon light, a comprehensive understanding of metabolism in these organisms requires taking into account the effects of day-night transitions and circadian regulation. These events synchronize intracellular processes with the solar day. Accordingly, metabolism is controlled and structured differently in cyanobacteria than in heterotrophic bacteria. Thus, the approaches applied to engineering heterotrophic bacteria will need to be revised for the cyanobacterial chassis. Here, we summarize important findings related to diurnal metabolism in cyanobacteria and present open questions in the field.
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Affiliation(s)
- David G Welkie
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Benjamin E Rubin
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Spencer Diamond
- Department of Earth and Planetary Science, UC Berkeley, Berkeley, CA 94720, USA
| | - Rachel D Hood
- Department of Molecular and Cell Biology, UC Berkeley, Berkeley, CA 94720, USA
| | - David F Savage
- Department of Molecular and Cell Biology, UC Berkeley, Berkeley, CA 94720, USA
| | - Susan S Golden
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA 92093, USA; Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
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Comparative genomics reveals the molecular determinants of rapid growth of the cyanobacterium Synechococcus elongatus UTEX 2973. Proc Natl Acad Sci U S A 2018; 115:E11761-E11770. [PMID: 30409802 DOI: 10.1073/pnas.1814912115] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cyanobacteria are emerging as attractive organisms for sustainable bioproduction. We previously described Synechococcus elongatus UTEX 2973 as the fastest growing cyanobacterium known. Synechococcus 2973 exhibits high light tolerance and an increased photosynthetic rate and produces biomass at three times the rate of its close relative, the model strain Synechococcus elongatus 7942. The two strains differ at 55 genetic loci, and some of these loci must contain the genetic determinants of rapid photoautotrophic growth and improved photosynthetic rate. Using CRISPR/Cpf1, we performed a comprehensive mutational analysis of Synechococcus 2973 and identified three specific genes, atpA, ppnK, and rpaA, with SNPs that confer rapid growth. The fast-growth-associated allele of each gene was then used to replace the wild-type alleles in Synechococcus 7942. Upon incorporation, each allele successively increased the growth rate of Synechococcus 7942; remarkably, inclusion of all three alleles drastically reduced the doubling time from 6.8 to 2.3 hours. Further analysis revealed that our engineering effort doubled the photosynthetic productivity of Synechococcus 7942. We also determined that the fast-growth-associated allele of atpA yielded an ATP synthase with higher specific activity, while that of ppnK encoded a NAD+ kinase with significantly improved kinetics. The rpaA SNPs cause broad changes in the transcriptional profile, as this gene is the master output regulator of the circadian clock. This pioneering study has revealed the molecular basis for rapid growth, demonstrating that limited genetic changes can dramatically improve the growth rate of a microbe by as much as threefold.
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Köbler C, Schultz SJ, Kopp D, Voigt K, Wilde A. The role of the Synechocystis sp. PCC 6803 homolog of the circadian clock output regulator RpaA in day-night transitions. Mol Microbiol 2018; 110:847-861. [PMID: 30216574 DOI: 10.1111/mmi.14129] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 09/07/2018] [Accepted: 07/12/2018] [Indexed: 01/20/2023]
Abstract
Cyanobacteria exhibit rhythmic gene expression with a period length of 24 hours to adapt to daily environmental changes. In the model organism Synechococcuselongatus PCC 7942, the central oscillator consists of the three proteins KaiA, KaiB and KaiC and utilizes the histidine kinase SasA and its response regulator RpaA as output-signaling pathway. Synechocystis sp. PCC 6803 contains in addition to the canonical kaiAB1C1 gene cluster two further homologs of the kaiB and kaiC genes. Here, we demonstrate that the SasA-RpaA system interacts with the KaiAB1C1 core oscillator only. Interaction with KaiC2 and KaiC3 proteins was not detected, suggesting different signal transduction components for the clock homologs. Inactivation of rpaA in Synechocystis sp. PCC 6803 leads to reduced viability of the mutant in light-dark cycles, especially under mixotrophic growth conditions. Chemoheterotrophic growth of the ∆rpaA strain in the dark was abolished completely. Transcriptomic data revealed that RpaA is mainly involved in the regulation of genes related to CO2 - acclimation in the light and to carbon metabolism in the dark. Further, our results indicate a link between the circadian clock and phototaxis.
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Affiliation(s)
- Christin Köbler
- Faculty of Biology, Institute of Biology III, University of Freiburg, 79104, Freiburg, Germany
| | - Siri-Jasmin Schultz
- Faculty of Biology, Institute of Biology III, University of Freiburg, 79104, Freiburg, Germany
| | - Dominik Kopp
- Faculty of Biology, Institute of Biology III, University of Freiburg, 79104, Freiburg, Germany
| | - Karsten Voigt
- Faculty of Biology, Institute of Biology III, University of Freiburg, 79104, Freiburg, Germany
| | - Annegret Wilde
- Faculty of Biology, Institute of Biology III, University of Freiburg, 79104, Freiburg, Germany.,BIOSS Centre of Biological Signalling Studies, University of Freiburg, 79106, Freiburg, Germany
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Genome-wide fitness assessment during diurnal growth reveals an expanded role of the cyanobacterial circadian clock protein KaiA. Proc Natl Acad Sci U S A 2018; 115:E7174-E7183. [PMID: 29991601 DOI: 10.1073/pnas.1802940115] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The recurrent pattern of light and darkness generated by Earth's axial rotation has profoundly influenced the evolution of organisms, selecting for both biological mechanisms that respond acutely to environmental changes and circadian clocks that program physiology in anticipation of daily variations. The necessity to integrate environmental responsiveness and circadian programming is exemplified in photosynthetic organisms such as cyanobacteria, which depend on light-driven photochemical processes. The cyanobacterium Synechococcus elongatus PCC 7942 is an excellent model system for dissecting these entwined mechanisms. Its core circadian oscillator, consisting of three proteins, KaiA, KaiB, and KaiC, transmits time-of-day signals to clock-output proteins, which reciprocally regulate global transcription. Research performed under constant light facilitates analysis of intrinsic cycles separately from direct environmental responses but does not provide insight into how these regulatory systems are integrated during light-dark cycles. Thus, we sought to identify genes that are specifically necessary in a day-night environment. We screened a dense bar-coded transposon library in both continuous light and daily cycling conditions and compared the fitness consequences of loss of each nonessential gene in the genome. Although the clock itself is not essential for viability in light-dark cycles, the most detrimental mutations revealed by the screen were those that disrupt KaiA. The screen broadened our understanding of light-dark survival in photosynthetic organisms, identified unforeseen clock-protein interaction dynamics, and reinforced the role of the clock as a negative regulator of a nighttime metabolic program that is essential for S. elongatus to survive in the dark.
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31
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High-throughput interaction screens illuminate the role of c-di-AMP in cyanobacterial nighttime survival. PLoS Genet 2018; 14:e1007301. [PMID: 29608558 PMCID: PMC5897029 DOI: 10.1371/journal.pgen.1007301] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 04/12/2018] [Accepted: 03/08/2018] [Indexed: 11/19/2022] Open
Abstract
The broadly conserved signaling nucleotide cyclic di-adenosine monophosphate (c-di-AMP) is essential for viability in most bacteria where it has been studied. However, characterization of the cellular functions and metabolism of c-di-AMP has largely been confined to the class Bacilli, limiting our functional understanding of the molecule among diverse phyla. We identified the cyclase responsible for c-di-AMP synthesis and characterized the molecule’s role in survival of darkness in the model photosynthetic cyanobacterium Synechococcus elongatus PCC 7942. In addition to the use of traditional genetic, biochemical, and proteomic approaches, we developed a high-throughput genetic interaction screen (IRB-Seq) to determine pathways where the signaling nucleotide is active. We found that in S. elongatus c-di-AMP is produced by an enzyme of the diadenylate cyclase family, CdaA, which was previously unexplored experimentally. A cdaA-null mutant experiences increased oxidative stress and death during the nighttime portion of day-night cycles, in which potassium transport is implicated. These findings suggest that c-di-AMP is biologically active in cyanobacteria and has non-canonical roles in the phylum including oxidative stress management and day-night survival. The pipeline and analysis tools for IRB-Seq developed for this study constitute a quantitative high-throughput approach for studying genetic interactions. Cyclic di-adenosine monophosphate (c-di-AMP) is a molecule that has significant roles in many microorganisms. This work shows the existence of c-di-AMP for the first time in photosynthetic microorganisms, cyanobacteria, and demonstrates its role in survival during the light-to-dark shifts that occur in day-night cycles. Despite the obvious importance of adaptation to these daily cycles for organisms that are fundamentally reliant on light, such as cyanobacteria, understanding of diurnal physiology is lacking because most cyanobacterial research is conducted during growth in constant light. To identify other players in c-di-AMP’s function we developed a low-cost and efficient method for finding interactions between genes. The technique combines one mutation, in this case for the gene that encodes the enzyme for synthesis of c-di-AMP, with thousands of other individual mutations to find pairwise interactions that affect fitness of the resulting mutants. Mutants are tagged with DNA barcodes to allow their survival to be easily tracked in a population of cells. The method enables us to place the function of c-di-AMP within the context of pathways previously known to be involved in day-night survival. Taken together, this work expands the known roles of c-di-AMP, improves our understanding of cyanobacterial survival in day-night cycles, and presents an improved approach for determining genetic interactions.
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Tan X, Hou S, Song K, Georg J, Klähn S, Lu X, Hess WR. The primary transcriptome of the fast-growing cyanobacterium Synechococcus elongatus UTEX 2973. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:218. [PMID: 30127850 PMCID: PMC6091082 DOI: 10.1186/s13068-018-1215-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 07/25/2018] [Indexed: 05/04/2023]
Abstract
BACKGROUND Cyanobacteria have shown promising potential for the production of various biofuels and chemical feedstocks. Synechococcus elongatus UTEX 2973 is a fast-growing strain with pronounced tolerance to high temperatures and illumination. Hence, this strain appears to be ideal for the development of photosynthetic biotechnology. However, molecular insights on how this strain can rapidly accumulate biomass and carbohydrates under high-light and high-temperature conditions are lacking. RESULTS Differential RNA-Sequencing (dRNA-Seq) enabled the genome-wide identification of 4808 transcription start sites (TSSs) in S. elongatus UTEX 2973 using a background reduction algorithm. High light promoted the transcription of genes associated with central metabolic pathways, whereas the highly induced small RNA (sRNA) PsrR1 likely contributed to the repression of phycobilisome genes and the accelerated glycogen accumulation rates measured under this condition. Darkness caused transcriptome remodeling with a decline in the expression of genes for carbon fixation and other major metabolic pathways and an increase in the expression of genes for glycogen catabolism and Calvin cycle inhibitor CP12. Two of the identified TSSs drive the transcription of highly abundant sRNAs in darkness. One of them is widely conserved throughout the cyanobacterial phylum. Its gene is fused to a protein-coding gene in some species, illustrating the evolutionary origin of sRNAs from an mRNA 3'-end. CONCLUSIONS Our comprehensive set of genome-wide mapped TSSs, sRNAs and promoter activities will be valuable for projects requiring precise information about the control of transcription aimed at metabolic engineering and the elucidation of stress acclimation mechanisms in this promising strain.
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Affiliation(s)
- Xiaoming Tan
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, 266101 China
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
- Present Address: College of Life Sciences, Hubei University, 368 Youyi Avenue, Wuchang District, Wuhan, 430062 China
| | - Shengwei Hou
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
| | - Kuo Song
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, 266101 China
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
| | - Jens Georg
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
| | - Stephan Klähn
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
- Department of Solar Materials, Helmholtz Centre for Environmental Research-UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Xuefeng Lu
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, 266101 China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, No. 1 Wenhai Road, Qingdao, 266237 China
| | - Wolfgang R. Hess
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
- Freiburg Institute for Advanced Studies, University of Freiburg, Albertstraße 19, 79104 Freiburg, Germany
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Piechura JR, Amarnath K, O'Shea EK. Natural changes in light interact with circadian regulation at promoters to control gene expression in cyanobacteria. eLife 2017; 6:32032. [PMID: 29239721 PMCID: PMC5785211 DOI: 10.7554/elife.32032] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/13/2017] [Indexed: 12/31/2022] Open
Abstract
The circadian clock interacts with other regulatory pathways to tune physiology to predictable daily changes and unexpected environmental fluctuations. However, the complexity of circadian clocks in higher organisms has prevented a clear understanding of how natural environmental conditions affect circadian clocks and their physiological outputs. Here, we dissect the interaction between circadian regulation and responses to fluctuating light in the cyanobacterium Synechococcus elongatus. We demonstrate that natural changes in light intensity substantially affect the expression of hundreds of circadian-clock-controlled genes, many of which are involved in key steps of metabolism. These changes in expression arise from circadian and light-responsive control of RNA polymerase recruitment to promoters by a network of transcription factors including RpaA and RpaB. Using phenomenological modeling constrained by our data, we reveal simple principles that underlie the small number of stereotyped responses of dusk circadian genes to changes in light. Living things face daily, predictable challenges due to the regular day and night cycle imposed by the Earth’s rotation. Many of them have evolved an internal ‘circadian’ clock to anticipate daily changes in the environment. However, nature can also change in unpredictable ways, and in order to survive, organisms must account for both the time of day stipulated by their clocks and changes in their present environment. For example, cyanobacteria depend on the sun for survival and must cope with light variations throughout the day and the absence of light at nighttime. Circadian clocks are made up of specific genes and their proteins. Most of what we know about how these clocks control the behavior of an organism comes from experiments performed under constant conditions. Previous research has shown that under such circumstances, the circadian clock of cyanobacteria periodically turns on a set of genes every 24 hours via a protein called RpaA. However, to understand how cyanobacteria use this clock, we must know how it works in a fluctuating environment. To test this, Piechura, Amarnath and O’Shea measured the activation of genes in cyanobacteria that had been exposed to changes in light mimicking those in nature. Compared to constant conditions, fluctuating light drastically changed the timing of activation of circadian genes. When light decreased – as it would in nature during sunset or if a cloud blocks the sun – the circadian genes were activated. Changes in light did not change the ‘ticking’ of the clock, but did affect the ability of RpaA to turn on circadian genes. Moreover, the activity of a second protein called RpaB increased when light decreased and the genes were activated. Thus, cyanobacteria switch on circadian genes as the sun is setting or during unexpected shade, likely through RpaA and RpaB, to help them survive without light. This study shows that circadian clocks activate genes differently in the real world compared to unnatural, constant conditions. This may prompt scientists to think carefully about how an organism’s natural environment can affect its inner workings. A next step will be to see how else light affects circadian gene levels. A deeper understanding of how cyanobacteria control their genes in a natural environment will be useful for scientists who engineer these organisms to produce biofuels from sunlight.
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Affiliation(s)
- Joseph Robert Piechura
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States.,FAS Center for Systems Biology, Harvard University, Cambridge, United States.,Howard Hughes Medical Institute, Harvard University, Cambridge, United States
| | - Kapil Amarnath
- FAS Center for Systems Biology, Harvard University, Cambridge, United States.,Howard Hughes Medical Institute, Harvard University, Cambridge, United States
| | - Erin K O'Shea
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States.,FAS Center for Systems Biology, Harvard University, Cambridge, United States.,Howard Hughes Medical Institute, Harvard University, Cambridge, United States.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
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