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Li C, Liao H, Xu L, Wang C, Yao M, Wang J, Li X. Comparative genomics reveals the adaptation of ammonia-oxidising Thaumarchaeota to arid soils. Environ Microbiol 2024; 26:e16601. [PMID: 38454574 DOI: 10.1111/1462-2920.16601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 02/09/2024] [Indexed: 03/09/2024]
Abstract
Thaumarchaeota are predominant in oligotrophic habitats such as deserts and arid soils, but their adaptations to these arid conditions are not well understood. In this study, we assembled 23 Thaumarchaeota genomes from arid and semi-arid soils collected from the Inner Mongolia Steppe and the Qinghai-Tibet Plateau. Using a comparative genomics approach, integrated with 614 Thaumarchaeota genomes from public databases, we identified the traits and evolutionary forces that contribute to their adaptations to aridity. Our results showed that the newly assembled genomes represent an early diverging group within the lineage of ammonia-oxidising Thaumarchaeota. While the genomic functions previously identified in arid soil lineages were conserved across terrestrial, shallow-ocean and deep-ocean lineages, several traits likely contribute to Thaumarchaeota's adaptation to aridity. These include chlorite dismutase, arsenate reductase, V-type ATPase and genes dealing with oxidative stresses. The acquisition and loss of traits at the last common ancestor of arid soil lineages may have facilitated the specialisation of Thaumarchaeota in arid soils. Additionally, the acquisition of unique adaptive traits, such as a urea transporter, Ca2+ :H+ antiporter, mannosyl-3-phosphoglycerate synthase and phosphatase, DNA end-binding protein Ku and phage shock protein A, further distinguishes arid soil Thaumarchaeota. This study provides evidence for the adaptations of Thaumarchaeota to arid soil, enhancing our understanding of the nitrogen and carbon cycling driven by Thaumarchaeota in drylands.
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Affiliation(s)
- Chaonan Li
- Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang, China
| | - Haijun Liao
- Engineering Research Center of Chuanxibei RHS Construction at Mianyang Normal University of Sichuan Province, Mianyang Normal University, Mianyang, China
| | - Lin Xu
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, China
| | - Changting Wang
- Institute of Qinghai-Tibet Plateau, Southwest Minzu University, Chengdu, China
| | - Minjie Yao
- Engineering Research Center of Soil Remediation of Fujian Province University, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Junming Wang
- Section of Climate Science, Illinois State Water Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Champaign, Illinois, USA
| | - Xiangzhen Li
- Engineering Research Center of Soil Remediation of Fujian Province University, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
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2
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Niu W, Zhou W, Lu S, Vu T, Jayaraman V, Faraldo-Gómez JD, Zheng L. Ca 2+ efflux facilitated by co-transport of inorganic phosphate anion in the H +/Ca 2+ antiporter YfkE. Commun Biol 2023; 6:573. [PMID: 37248347 PMCID: PMC10227063 DOI: 10.1038/s42003-023-04944-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 05/15/2023] [Indexed: 05/31/2023] Open
Abstract
Ca2+ is an important signaling messenger. In microorganisms, fungi, and plants, H+/Ca2+ antiporters (CAX) are known to play key roles in the homeostasis of intracellular Ca2+ by catalyzing its efflux across the cell membrane. Here, we reveal that the bacterial CAX homolog YfkE transports Ca2+ in two distinct modes: a low-flux H+/Ca2+ exchange mode and a high-flux mode in which Ca2+ and phosphate ions are co-transported (1:1) in exchange for H+. Coupling with phosphate greatly accelerates the Ca2+ efflux activity of YfkE. Our studies reveal that Ca2+ and phosphate bind to adjacent sites in a central translocation pathway and lead to mechanistic insights that explain how this CAX alters its conserved alpha-repeat motifs to adopt phosphate as a specific "transport chaperon" for Ca2+ translocation. This finding uncovers a co-transport mechanism within the CAX family that indicates this class of proteins contributes to the cellular homeostasis of both Ca2+ and phosphate.
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Affiliation(s)
- Wei Niu
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, the University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX, USA
| | - Wenchang Zhou
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Shuo Lu
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, the University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX, USA
| | - Trung Vu
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, the University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX, USA
| | - Vasanthi Jayaraman
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, the University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX, USA
| | - José D Faraldo-Gómez
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Lei Zheng
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, the University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX, USA.
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3
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Improvement of Lignocellulolytic Enzyme Production Mediated by Calcium Signaling in Bacillus subtilis Z2 under Graphene Oxide Stress. Appl Environ Microbiol 2022; 88:e0096022. [PMID: 36121214 PMCID: PMC9552604 DOI: 10.1128/aem.00960-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An increase in exoenzyme production can be enhanced by environmental stresses such as graphene oxide (GO) stress, but the link between the two events is still unclear. In this work, the effect of GO as an environmental stress factor on exoenzyme (lignocellulolytic enzyme, amylase, peptidase, and protease) biosynthesis was investigated in Bacillus subtilis Z2, and a plausible mechanism by which cytosolic Ca2+ regulates lignocellulolytic enzyme production in B. subtilis Z2 subjected to GO stress was proposed. The filter paper-hydrolyzing (FPase [representing total cellulase]), carboxymethylcellulase (CMCase [representing endoglucanase]), and β-glucosidase activities and extracellular protein concentration of the wild-type strain under 10 μg/mL GO stress were 1.37-, 1.64-, 1.24-, and 1.16-fold those of the control (without GO stress), respectively. Correspondingly, the transcription levels of lignocellulolytic enzyme genes, cytosolic Ca2+ level, and biomass concentration of B. subtilis were all increased. With lignocellulolytic enzyme from B. subtilis used to hydrolyze alkali-pretreated rice straw, the released reducing sugar concentration reached 265.53 mg/g, and the removal rates of cellulose, hemicellulose, and lignin were 52.4%, 30.1%, and 7.5%, respectively. Furthermore, transcriptome data revealed that intracellular Ca2+ homeostasis played a key role in regulating the levels of gene transcription related to the synthesis of lignocellulolytic enzymes and exoenzymes. Finally, the use of Ca2+ inhibitors (LaCl3 and EDTA) and deletion of spcF (a calmodulin-like protein gene) further demonstrated that the overexpression of those genes was regulated via calcium signaling in B. subtilis subjected to GO stress. IMPORTANCE To effectively convert lignocellulose into fermentable sugars, high lignocellulolytic enzyme loading is needed. Graphene oxide (GO) has been shown to promote exoenzyme (lignocellulolytic enzyme, amylase, peptidase, and protease) production in some microorganisms; however, the regulatory mechanism of the biosynthesis of lignocellulolytic enzymes under GO stress remains unclear. In this work, the lignocellulolytic enzyme production of B. subtilis under GO stress was investigated, and the potential mechanism by which B. subtilis enhanced lignocellulolytic enzyme production through the calcium signaling pathway under GO stress was proposed. This work revealed the role of calcium signaling in the production of enzymes under external environmental stress and provided a direction to facilitate lignocellulolytic enzyme production by B. subtilis.
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4
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Keren-Paz A, Maan H, Karunker I, Olender T, Kapishnikov S, Dersch S, Kartvelishvily E, Wolf SG, Gal A, Graumann PL, Kolodkin-Gal I. The roles of intracellular and extracellular calcium in Bacillus subtilis biofilms. iScience 2022; 25:104308. [PMID: 35663026 PMCID: PMC9160756 DOI: 10.1016/j.isci.2022.104308] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 03/26/2022] [Accepted: 04/22/2022] [Indexed: 11/06/2022] Open
Abstract
In nature, bacteria reside in biofilms– multicellular differentiated communities held together by an extracellular matrix. This work identified a novel subpopulation—mineral-forming cells—that is essential for biofilm formation in Bacillus subtilis biofilms. This subpopulation contains an intracellular calcium-accumulating niche, in which the formation of a calcium carbonate mineral is initiated. As the biofilm colony develops, this mineral grows in a controlled manner, forming a functional macrostructure that serves the entire community. Consistently, biofilm development is prevented by the inhibition of calcium uptake. Our results provide a clear demonstration of the orchestrated production of calcite exoskeleton, critical to morphogenesis in simple prokaryotes. The orchestrated formation of calcite scaffolds supports the morphogenesis of microbial biofilms A novel subpopulation—mineral-forming cells—is essential for biofilm formation This subpopulation contains an intracellular calcium-accumulating niche, supporting the formation of calcium carbonate Intracellular calcium homeostasis and calcium export are associated with a functional biofilm macrostructure
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Affiliation(s)
- Alona Keren-Paz
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Harsh Maan
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Iris Karunker
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Tsviya Olender
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Sergey Kapishnikov
- Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Simon Dersch
- Centre for Synthetic Microbiology (SYNMIKRO), Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany
| | | | - Sharon G Wolf
- Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Assaf Gal
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Peter L Graumann
- Centre for Synthetic Microbiology (SYNMIKRO), Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany
| | - Ilana Kolodkin-Gal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.,Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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5
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Zhai L, Xie J, Feng H, Sun S, Cheng K, Yao S. Mechanism of TonB-dependent transport system in Halomonas alkalicola CICC 11012s in response to alkaline stress. Extremophiles 2020; 25:39-49. [PMID: 33123748 DOI: 10.1007/s00792-020-01209-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 10/14/2020] [Indexed: 11/25/2022]
Abstract
Halomonas alkalicola CICC 11012s can grow at pH 12.5, the highest pH at which the organisms in the genus Halomonas can grow. Genomic analysis reveals that H. alkalicola adapts to alkaline stress using a variety of adaptive strategies; however, the detailed mechanism for its growth at high-alkaline conditions has not been elucidated. Therefore, in this study, the adaptations of H. alkalicola in response to extreme alkaline stress were investigated. A sharp decrease of alkaliphilic tolerance was observed in mutants E. coli ΔEctonB and H. alkalicola ΔHatonB. Expressions of the gene clusters encoding TonB-dependent transport system and iron complex transport system in H. alkalicola grown under extreme alkaline conditions were markedly up-regulated. We then compared the intracellular ionic iron content and iron-chelating ability of mutant strain with those of wild-type strain to understand the influence of TonB-dependent transport system on the alkaline responses. The results indicated that the presence of TonB-dependent transport system increased the alkaline tolerance of H. alkalicola grown at high-alkaline conditions, but had no effects when the strain was grown at neutral pH and low-alkaline conditions. Meanwhile, the presence of this system increased the transport and accumulation of ionic irons to maintain intracellular metabolic homeostasis, which in turn could increase the tolerance of the strain to extreme alkaline conditions. Based on the results, we established a model representing the interactions between TonB-dependent transport system, alkaline tolerance, and intracellular ionic iron that could help deepen the understanding of the alkaline response mechanism of alkaliphilic bacteria.
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Affiliation(s)
- Lei Zhai
- China Center of Industrial Culture Collection (CICC), China National Research Institute of Food and Fermentation Industries, Building 6, No. 24 Yard, Jiuxianqiao Middle Road, Chaoyang District, Beijing, China
| | - Jiuyan Xie
- China Center of Industrial Culture Collection (CICC), China National Research Institute of Food and Fermentation Industries, Building 6, No. 24 Yard, Jiuxianqiao Middle Road, Chaoyang District, Beijing, China
| | - Huijun Feng
- China Center of Industrial Culture Collection (CICC), China National Research Institute of Food and Fermentation Industries, Building 6, No. 24 Yard, Jiuxianqiao Middle Road, Chaoyang District, Beijing, China
| | - Sijia Sun
- China Center of Industrial Culture Collection (CICC), China National Research Institute of Food and Fermentation Industries, Building 6, No. 24 Yard, Jiuxianqiao Middle Road, Chaoyang District, Beijing, China
| | - Kun Cheng
- China Center of Industrial Culture Collection (CICC), China National Research Institute of Food and Fermentation Industries, Building 6, No. 24 Yard, Jiuxianqiao Middle Road, Chaoyang District, Beijing, China
| | - Su Yao
- China Center of Industrial Culture Collection (CICC), China National Research Institute of Food and Fermentation Industries, Building 6, No. 24 Yard, Jiuxianqiao Middle Road, Chaoyang District, Beijing, China.
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6
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Garg R, Borbora SM, Bansia H, Rao S, Singh P, Verma R, Balaji KN, Nagaraja V. Mycobacterium tuberculosis Calcium Pump CtpF Modulates the Autophagosome in an mTOR-Dependent Manner. Front Cell Infect Microbiol 2020; 10:461. [PMID: 33042857 PMCID: PMC7525011 DOI: 10.3389/fcimb.2020.00461] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 07/28/2020] [Indexed: 12/17/2022] Open
Abstract
Calcium is a very important second messenger, whose concentration in various cellular compartments is under tight regulation. A disturbance in the levels of calcium in these compartments can play havoc in the cell, as it regulates various cellular processes by direct or indirect mechanisms. Here, we have investigated the functional importance of a calcium transporting P2A ATPase, CtpF of Mycobacterium tuberculosis (Mtb) in the pathogen's interaction with the host. Among its uncanny ways of dealing with the host with umpteen strategies for survival and persistence in humans, CtpF is identified as a new player. The levels of ctpF are upregulated in macrophage stresses like hypoxia, high nitric oxide levels and acidic pH. Using confocal microscopy and fluorimetry, we show that CtpF effluxes calcium in macrophages in early stages of Mtb infection. Downregulation of ctpF expression by conditional knockdown resulted in perturbation of host calcium levels and consequent decreased activation of mTOR. We present a mechanism how calcium efflux by the pathogen inhibits mTOR-dependent autophagy and enhances bacterial survival. Our work highlights how Mtb engages its metal efflux pumps to exploit host autophagic process for its proliferation.
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Affiliation(s)
- Rajni Garg
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India.,Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Salik Miskat Borbora
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Harsh Bansia
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Sandhya Rao
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Prakruti Singh
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Rinkee Verma
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | | | - Valakunja Nagaraja
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India.,Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
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7
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Intracellular Ca 2+ regulation of H +/Ca 2+ antiporter YfkE mediated by a Ca 2+ mini-sensor. Proc Natl Acad Sci U S A 2020; 117:10313-10321. [PMID: 32341169 DOI: 10.1073/pnas.1918604117] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The H+/Ca2+ (calcium ion) antiporter (CAX) plays an important role in maintaining cellular Ca2+ homeostasis in bacteria, yeast, and plants by promoting Ca2+ efflux across the cell membranes. However, how CAX facilitates Ca2+ balance in response to dynamic cytosolic Ca2+ perturbations is unknown. Here, we identified a type of Ca2+ "mini-sensor" in YfkE, a bacterial CAX homolog from Bacillus subtilis. The mini-sensor is formed by six tandem carboxylate residues within the transmembrane (TM)5-6 loop on the intracellular membrane surface. Ca2+ binding to the mini-sensor triggers the transition of the transport mode of YfkE from a high-affinity to a low-affinity state. Molecular dynamics simulation and fluorescence resonance energy transfer analysis suggest that Ca2+ binding to the mini-sensor causes an adjacent segment, namely, the exchanger inhibitory peptide (XIP), to move toward the Ca2+ translocation pathway to interact with TM2a in an inward-open cavity. The specific interaction was demonstrated with a synthetic peptide of the XIP, which inhibits YfkE transport and interrupts conformational changes mediated by the mini-sensor. By comparing the apo and Ca2+-bound CAX structures, we propose the following Ca2+ transport regulatory mechanism of YfkE: Ca2+ binding to the mini-sensor induces allosteric conformational changes in the Ca2+ translocation pathway via the XIP, resulting in a rearrangement of the Ca2+-binding transport site in the midmembrane. Since the Ca2+ mini-sensor and XIP sequences are also identified in other CAX homologs and/or Ca2+ transporters, including the mammalian Na+/Ca2+ exchanger (NCX), our study provides a regulatory mechanism for the Ca2+/cation transporter superfamily.
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Zhai L, Xie J, Lin Y, Cheng K, Wang L, Yue F, Guo J, Liu J, Yao S. Genome sequencing and heterologous expression of antiporters reveal alkaline response mechanisms of Halomonas alkalicola. Extremophiles 2017; 22:221-231. [PMID: 29270851 DOI: 10.1007/s00792-017-0991-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 12/08/2017] [Indexed: 11/30/2022]
Abstract
Halomonas alkalicola CICC 11012s is an alkaliphilic and halotolerant bacterium isolated from a soap-making tank (pH > 10) from a household-product plant. This strain can propagate at pH 12.5, which is fatal to most bacteria. Genomic analysis revealed that the genome size was 3,511,738 bp and contained 3295 protein-coding genes, including a complete cell wall and plasma membrane lipid biosynthesis pathway. Furthermore, four putative Na+/H+ and K+/H+ antiporter genes, or gene clusters, designated as HaNhaD, HaNhaP, HaMrp and HaPha, were identified within the genome. Heterologous expression of these genes in antiporter-deficient Escherichia coli indicated that HaNhaD, an Na+/H+ antiporter, played a dominant role in Na+ tolerance and pH homeostasis in acidic, neutral and alkaline environments. In addition, HaMrp exhibited Na+ tolerance; however, it functioned mainly in alkaline conditions. Both HaNhaP and HaPha were identified as K+/H+ antiporters that played an important role in high alkalinity and salinity. In summary, genome analysis and heterologous expression experiments demonstrated that a complete set of adaptive strategies have been developed by the double extremophilic strain CICC 11012s in response to alkalinity and salinity. Specifically, four antiporters exhibiting different physiological roles for different situations worked together to support the strain in harsh surroundings.
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Affiliation(s)
- Lei Zhai
- China Center of Industrial Culture Collection (CICC), China National Research Institute of Food and Fermentation Industries, Beijing, 100015, People's Republic of China
| | - Jiuyan Xie
- China Center of Industrial Culture Collection (CICC), China National Research Institute of Food and Fermentation Industries, Beijing, 100015, People's Republic of China
| | - Yafang Lin
- Procter & Gamble Technologies (Beijing) Ltd, Beijing, 101312, People's Republic of China
| | - Kun Cheng
- China Center of Industrial Culture Collection (CICC), China National Research Institute of Food and Fermentation Industries, Beijing, 100015, People's Republic of China
| | - Lijiang Wang
- Procter & Gamble Technologies (Beijing) Ltd, Beijing, 101312, People's Republic of China
| | - Feng Yue
- Procter & Gamble Technologies (Beijing) Ltd, Beijing, 101312, People's Republic of China
| | - Jingyan Guo
- Procter & Gamble Technologies (Beijing) Ltd, Beijing, 101312, People's Republic of China
| | - Jiquan Liu
- Procter & Gamble International Operations SA Singapore Branch, 70 Biopolis Street, Singapore, 138547, Singapore.
| | - Su Yao
- China Center of Industrial Culture Collection (CICC), China National Research Institute of Food and Fermentation Industries, Beijing, 100015, People's Republic of China.
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A Novel Calcium Uptake Transporter of Uncharacterized P-Type ATPase Family Supplies Calcium for Cell Surface Integrity in Mycobacterium smegmatis. mBio 2017; 8:mBio.01388-17. [PMID: 28951477 PMCID: PMC5615198 DOI: 10.1128/mbio.01388-17] [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] [Indexed: 11/20/2022] Open
Abstract
Ca2+ plays an important role in the physiology of bacteria. Intracellular Ca2+ concentrations are tightly maintained in the nanomolar range. Molecular mechanisms of Ca2+ uptake in bacteria remain elusive. Here we show that CtpE is responsible for Ca2+ uptake in Mycobacterium smegmatis. It represents a previously uncharacterized P-type ATPase family in bacteria. Disruption of ctpE in M. smegmatis resulted in a mutant with impaired growth under Ca2+-deficient conditions. The growth defect of the mutant could be rescued by Ca2+ or by ectopic expression of ctpE from M. smegmatis or the orthologous gene (Rv0908) from Mycobacterium tuberculosis H37Rv. Radioactive transport assays revealed that CtpE is a Ca2+-specific transporter. Ca2+ deficiency increased expression of ctpE, resulting in increased 45Ca2+ accumulation in cells. ctpE is a gene that is part of an operon, which is negatively regulated by Ca2+. The ctpE mutant also showed hypersensitivity to polymyxin B, increased biofilm formation, and higher cell aggregation, indicating cell envelope defects. Our work establishes, for the first time, the presence of Ca2+ uptake pumps of the energy-dependent P-type ATPase superfamily in bacteria and also implicates that intracellular Ca2+ is essential for growth and cell envelope integrity in M. smegmatis. Ca2+ is essential for gene regulation, enzymatic activity, and maintenance of structural integrity of cell walls in bacteria. Bacteria maintain intracellular calcium concentrations in a narrow range, creating a gradient with low cytoplasmic calcium concentration and high extracellular calcium concentration. Due to this steep gradient, active pumps belonging to family 2 of P-type ATPases and antiporters are used for Ca2+ efflux, whereas Ca2+ uptake is usually carried out by channels. Molecular mechanisms of Ca2+ uptake in bacteria are still elusive and are mainly limited to a nonproteinaceous channel in Escherichia coli and a pH-dependent channel protein from Bacillus subtilis. Energy-dependent active transporters are not reported for Ca2+ uptake from any organism. Here we show that CtpE belonging to a family of previously uncharacterized bacterial P-type ATPases is involved in specific uptake of Ca2+ into Mycobacterium smegmatis. We also demonstrate that intracellular Ca2+ obtained through CtpE is essential for growth and maintenance of cell surface properties under Ca2+-deficient conditions.
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10
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A high-throughput genetic screen identifies previously uncharacterized Borrelia burgdorferi genes important for resistance against reactive oxygen and nitrogen species. PLoS Pathog 2017; 13:e1006225. [PMID: 28212410 PMCID: PMC5333916 DOI: 10.1371/journal.ppat.1006225] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 03/02/2017] [Accepted: 02/08/2017] [Indexed: 02/06/2023] Open
Abstract
Borrelia burgdorferi, the causative agent of Lyme disease in humans, is exposed to reactive oxygen and nitrogen species (ROS and RNS) in both the tick vector and vertebrate reservoir hosts. B. burgdorferi contains a limited repertoire of canonical oxidative stress response genes, suggesting that novel gene functions may be important for protection of B. burgdorferi against ROS or RNS exposure. Here, we use transposon insertion sequencing (Tn-seq) to conduct an unbiased search for genes involved in resistance to nitric oxide, hydrogen peroxide, and tertiary-butyl hydroperoxide in vitro. The screens identified 66 genes whose disruption resulted in increased susceptibility to at least one of the stressors. These genes include previously characterized mediators of ROS and RNS resistance (including components of the nucleotide excision repair pathway and a subunit of a riboflavin transporter), as well as novel putative resistance candidates. DNA repair mutants were among the most sensitive to RNS in the Tn-seq screen, and survival assays with individual Tn mutants confirmed that the putative ribonuclease BB0839 is involved in resistance to nitric oxide. In contrast, mutants lacking predicted inner membrane proteins or transporters were among the most sensitive to ROS, and the contribution of three such membrane proteins (BB0017, BB0164, and BB0202) to ROS sensitivity was confirmed using individual Tn mutants and complemented strains. Further analysis showed that levels of intracellular manganese are significantly reduced in the Tn::bb0164 mutant, identifying a novel role for BB0164 in B. burgdorferi manganese homeostasis. Infection of C57BL/6 and gp91phox-/- mice with a mini-library of 39 Tn mutants showed that many of the genes identified in the in vitro screens are required for infectivity in mice. Collectively, our data provide insight into how B. burgdorferi responds to ROS and RNS and suggests that this response is relevant to the in vivo success of the organism.
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11
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A novel type bacterial flagellar motor that can use divalent cations as a coupling ion. Sci Rep 2016; 6:19773. [PMID: 26794857 PMCID: PMC4726428 DOI: 10.1038/srep19773] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 12/18/2015] [Indexed: 12/25/2022] Open
Abstract
The bacterial flagellar motor is a sophisticated nanomachine embedded in the cell envelope and powered by an electrochemical gradient of H(+), Na(+), or K(+)across the cytoplasmic membrane. Here we describe a new member of the bacterial flagellar stator channel family (MotAB1 of Paenibacillus sp. TCA20 (TCA-MotAB1)) that is coupled to divalent cations (Ca(2+)and Mg(2+)). In the absence of divalent cations of alkaline earth metals, no swimming was observed in Paenibacillus sp. TCA20, which grows optimally in Ca(2+)-rich environments. This pattern was confirmed by swimming assays of a stator-free Bacillus subtilis mutant expressing TCA-MotAB1. Both a stator-free and major Mg(2+)uptake system-deleted B. subtilis mutant expressing TCA-MotAB1 complemented both growth and motility deficiency under low Mg(2+)conditions and exhibited [Mg(2+)]in identical to that of the wild-type. This is the first report of a flagellar motor that can use Ca(2+)and Mg(2+)as coupling ions. These findings will promote the understanding of the operating principles of flagellar motors and molecular mechanisms of ion selectivity.
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12
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Calcium binding proteins and calcium signaling in prokaryotes. Cell Calcium 2014; 57:151-65. [PMID: 25555683 DOI: 10.1016/j.ceca.2014.12.006] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/08/2014] [Accepted: 12/09/2014] [Indexed: 11/20/2022]
Abstract
With the continued increase of genomic information and computational analyses during the recent years, the number of newly discovered calcium binding proteins (CaBPs) in prokaryotic organisms has increased dramatically. These proteins contain sequences that closely resemble a variety of eukaryotic calcium (Ca(2+)) binding motifs including the canonical and pseudo EF-hand motifs, Ca(2+)-binding β-roll, Greek key motif and a novel putative Ca(2+)-binding domain, called the Big domain. Prokaryotic CaBPs have been implicated in diverse cellular activities such as division, development, motility, homeostasis, stress response, secretion, transport, signaling and host-pathogen interactions. However, the majority of these proteins are hypothetical, and only few of them have been studied functionally. The finding of many diverse CaBPs in prokaryotic genomes opens an exciting area of research to explore and define the role of Ca(2+) in organisms other than eukaryotes. This review presents the most recent developments in the field of CaBPs and novel advancements in the role of Ca(2+) in prokaryotes.
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Draft Genome Sequence of Calcium-Dependent Paenibacillus sp. Strain TCA20, Isolated from a Hot Spring Containing a High Concentration of Calcium Ions. GENOME ANNOUNCEMENTS 2014; 2:2/5/e00866-14. [PMID: 25189580 PMCID: PMC4155585 DOI: 10.1128/genomea.00866-14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Calcium-dependent Paenibacillus sp. strain TCA20 was isolated from a water sample of a hot spring containing a high concentration of calcium ions. Here, we report the draft genome sequence of this bacterium, which may be the basis for the research of calcium ion homeostasis.
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Calcium homeostasis in Pseudomonas aeruginosa requires multiple transporters and modulates swarming motility. Cell Calcium 2013; 54:350-61. [PMID: 24074964 DOI: 10.1016/j.ceca.2013.08.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 08/21/2013] [Accepted: 08/30/2013] [Indexed: 11/21/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen causing severe acute and chronic infections. Earlier we have shown that calcium (Ca(2+)) induces P. aeruginosa biofilm formation and production of virulence factors. To enable further studies of the regulatory role of Ca(2+), we characterized Ca(2+) homeostasis in P. aeruginosa PAO1 cells. By using Ca(2+)-binding photoprotein aequorin, we determined that the concentration of free intracellular Ca(2+) ([Ca(2+)]in) is 0.14±0.05μM. In response to external Ca(2+), the [Ca(2+)]in quickly increased at least 13-fold followed by a multi-phase decline by up to 73%. Growth at elevated Ca(2+) modulated this response. Treatment with inhibitors known to affect Ca(2+) channels, monovalent cations gradient, or P-type and F-type ATPases impaired [Ca(2+)]in response, suggesting the importance of the corresponding mechanisms in Ca(2+) homeostasis. To identify Ca(2+) transporters maintaining this homeostasis, bioinformatic and LC-MS/MS-based membrane proteomic analyses were used. [Ca(2+)]in homeostasis was monitored for seven Ca(2+)-affected and eleven bioinformatically predicted transporters by using transposon insertion mutants. Disruption of P-type ATPases PA2435, PA3920, and ion exchanger PA2092 significantly impaired Ca(2+) homeostasis. The lack of PA3920 and vanadate treatment abolished Ca(2+)-induced swarming, suggesting the role of the P-type ATPase in regulating P. aeruginosa response to Ca(2+).
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Crystal structure of Ca2+/H+ antiporter protein YfkE reveals the mechanisms of Ca2+ efflux and its pH regulation. Proc Natl Acad Sci U S A 2013; 110:11367-72. [PMID: 23798403 DOI: 10.1073/pnas.1302515110] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ca(2+) efflux by Ca(2+) cation antiporter (CaCA) proteins is important for maintenance of Ca(2+) homeostasis across the cell membrane. Recently, the monomeric structure of the prokaryotic Na(+)/Ca(2+) exchanger (NCX) antiporter NCX_Mj protein from Methanococcus jannaschii shows an outward-facing conformation suggesting a hypothesis of alternating substrate access for Ca(2+) efflux. To demonstrate conformational changes essential for the CaCA mechanism, we present the crystal structure of the Ca(2+)/H(+) antiporter protein YfkE from Bacillus subtilis at 3.1-Å resolution. YfkE forms a homotrimer, confirmed by disulfide crosslinking. The protonated state of YfkE exhibits an inward-facing conformation with a large hydrophilic cavity opening to the cytoplasm in each protomer and ending in the middle of the membrane at the Ca(2+)-binding site. A hydrophobic "seal" closes its periplasmic exit. Four conserved α-repeat helices assemble in an X-like conformation to form a Ca(2+)/H(+) exchange pathway. In the Ca(2+)-binding site, two essential glutamate residues exhibit different conformations compared with their counterparts in NCX_Mj, whereas several amino acid substitutions occlude the Na(+)-binding sites. The structural differences between the inward-facing YfkE and the outward-facing NCX_Mj suggest that the conformational transition is triggered by the rotation of the kink angles of transmembrane helices 2 and 7 and is mediated by large conformational changes in their adjacent transmembrane helices 1 and 6. Our structural and mutational analyses not only establish structural bases for mechanisms of Ca(2+)/H(+) exchange and its pH regulation but also shed light on the evolutionary adaptation to different energy modes in the CaCA protein family.
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Schaedler TA, Tong Z, van Veen HW. The multidrug transporter LmrP protein mediates selective calcium efflux. J Biol Chem 2012; 287:27682-90. [PMID: 22730320 DOI: 10.1074/jbc.m112.372334] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
LmrP is a major facilitator superfamily multidrug transporter from Lactococcus lactis that mediates the efflux of cationic amphiphilic substrates from the cell in a proton-motive force-dependent fashion. Interestingly, motif searches and docking studies suggested the presence of a putative Ca(2+)-binding site close to the interface between the two halves of inward facing LmrP. Binding experiments with radioactive (45)Ca(2+) demonstrated the presence of a high affinity Ca(2+)-binding site in purified LmrP, with an apparent K(d) of 7.2 μm, which is selective for Ca(2+) and Ba(2+) but not for Mn(2+), Mg(2+), or Co(2+). Consistent with our structure model and analogous to crystal structures of EF hand Ca(2+)-binding proteins, two carboxylates (Asp-235 and Glu-327) were found to be critical for (45)Ca(2+) binding. Using (45)Ca(2+) and a fluorescent Ca(2+)-selective probe, calcium transport measurements in intact cells, inside-out membrane vesicles, and proteoliposomes containing functionally reconstituted purified protein provided strong evidence for active efflux of Ca(2+) by LmrP with an apparent K(t) of 8.6 μm via electrogenic exchange with three or more protons. These observations demonstrate for the first time that LmrP mediates selective calcium/proton antiport and raise interesting questions about the functional and physiological links between this reaction and that of multidrug transport.
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Stael S, Wurzinger B, Mair A, Mehlmer N, Vothknecht UC, Teige M. Plant organellar calcium signalling: an emerging field. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:1525-42. [PMID: 22200666 PMCID: PMC3966264 DOI: 10.1093/jxb/err394] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
This review provides a comprehensive overview of the established and emerging roles that organelles play in calcium signalling. The function of calcium as a secondary messenger in signal transduction networks is well documented in all eukaryotic organisms, but so far existing reviews have hardly addressed the role of organelles in calcium signalling, except for the nucleus. Therefore, a brief overview on the main calcium stores in plants-the vacuole, the endoplasmic reticulum, and the apoplast-is provided and knowledge on the regulation of calcium concentrations in different cellular compartments is summarized. The main focus of the review will be the calcium handling properties of chloroplasts, mitochondria, and peroxisomes. Recently, it became clear that these organelles not only undergo calcium regulation themselves, but are able to influence the Ca(2+) signalling pathways of the cytoplasm and the entire cell. Furthermore, the relevance of recent discoveries in the animal field for the regulation of organellar calcium signals will be discussed and conclusions will be drawn regarding potential homologous mechanisms in plant cells. Finally, a short overview on bacterial calcium signalling is included to provide some ideas on the question where this typically eukaryotic signalling mechanism could have originated from during evolution.
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Affiliation(s)
- Simon Stael
- Department of Biochemistry and Cell Biology, MFPL, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria
| | - Bernhard Wurzinger
- Department of Biochemistry and Cell Biology, MFPL, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria
| | - Andrea Mair
- Department of Biochemistry and Cell Biology, MFPL, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria
| | - Norbert Mehlmer
- Department of Biology I, Botany, LMU Munich, Großhaderner Str. 2, D-82152 Planegg-Martinsried, Germany
| | - Ute C. Vothknecht
- Department of Biology I, Botany, LMU Munich, Großhaderner Str. 2, D-82152 Planegg-Martinsried, Germany
- Center for Integrated Protein Science (Munich) at the Department of Biology of the LMU Munich, D-81377 Munich, Germany
| | - Markus Teige
- Department of Biochemistry and Cell Biology, MFPL, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria
- To whom correspondence should be addressed.
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