1
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Pflüger T, Gschell M, Zhang L, Shnitsar V, Zabadné AJ, Zierep P, Günther S, Einsle O, Andrade SLA. How sensor Amt-like proteins integrate ammonium signals. SCIENCE ADVANCES 2024; 10:eadm9441. [PMID: 38838143 DOI: 10.1126/sciadv.adm9441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 04/30/2024] [Indexed: 06/07/2024]
Abstract
Unlike aquaporins or potassium channels, ammonium transporters (Amts) uniquely discriminate ammonium from potassium and water. This feature has certainly contributed to their repurposing as ammonium receptors during evolution. Here, we describe the ammonium receptor Sd-Amt1, where an Amt module connects to a cytoplasmic diguanylate cyclase transducer module via an HAMP domain. Structures of the protein with and without bound ammonium were determined to 1.7- and 1.9-Ångstrom resolution, depicting the ON and OFF states of the receptor and confirming the presence of a binding site for two ammonium cations that is pivotal for signal perception and receptor activation. The transducer domain was disordered in the crystals, and an AlphaFold2 prediction suggests that the helices linking both domains are flexible. While the sensor domain retains the trimeric fold formed by all Amt family members, the HAMP domains interact as pairs and serve to dimerize the transducer domain upon activation.
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Affiliation(s)
- Tobias Pflüger
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Mathias Gschell
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Lin Zhang
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Volodymyr Shnitsar
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Annas J Zabadné
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Paul Zierep
- Faculty of Chemistry and Pharmacy, Institute for Pharmaceutical Sciences, University Freiburg, Hermann-Herder-Str. 9, 79104 Freiburg, Germany
| | - Stefan Günther
- Faculty of Chemistry and Pharmacy, Institute for Pharmaceutical Sciences, University Freiburg, Hermann-Herder-Str. 9, 79104 Freiburg, Germany
| | - Oliver Einsle
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
- BIOSS Centre for Biological Signaling Studies, University Freiburg, Schänzlerstr. 1, 79104 Freiburg, Germany
| | - Susana L A Andrade
- Faculty of Chemistry and Pharmacy, Institute for Biochemistry, University Freiburg, Albertstr. 21, 79104 Freiburg, Germany
- BIOSS Centre for Biological Signaling Studies, University Freiburg, Schänzlerstr. 1, 79104 Freiburg, Germany
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2
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Guo Z, Ma XS, Ni SQ. Journey of the swift nitrogen transformation: Unveiling comammox from discovery to deep understanding. CHEMOSPHERE 2024; 358:142093. [PMID: 38679176 DOI: 10.1016/j.chemosphere.2024.142093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 04/02/2024] [Accepted: 04/19/2024] [Indexed: 05/01/2024]
Abstract
COMplete AMMonia OXidizer (comammox) refers to microorganisms that have the function of oxidizing NH4+ to NO3- alone. The discovery of comammox overturned the two-step theory of nitrification in the past century and triggered many important scientific questions about the nitrogen cycle in nature. This comprehensive review delves into the origin and discovery of comammox, providing a detailed account of its detection primers, clades metabolic variations, and environmental factors. An in-depth analysis of the ecological niche differentiation among ammonia oxidizers was also discussed. The intricate role of comammox in anammox systems and the relationship between comammox and nitrogen compound emissions are also discussed. Finally, the relationship between comammox and anammox is displayed, and the future research direction of comammox is prospected. This review reveals the metabolic characteristics and distribution patterns of comammox in ecosystems, providing new perspectives for understanding nitrogen cycling and microbial ecology. Additionally, it offers insights into the potential application value and prospects of comammox.
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Affiliation(s)
- Zheng Guo
- School of Environmental Science and Engineering, Shandong University, Shandong, 266237, China
| | - Xue Song Ma
- School of Environmental Science and Engineering, Shandong University, Shandong, 266237, China
| | - Shou-Qing Ni
- School of Environmental Science and Engineering, Shandong University, Shandong, 266237, China.
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3
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Qin W, Wei SP, Zheng Y, Choi E, Li X, Johnston J, Wan X, Abrahamson B, Flinkstrom Z, Wang B, Li H, Hou L, Tao Q, Chlouber WW, Sun X, Wells M, Ngo L, Hunt KA, Urakawa H, Tao X, Wang D, Yan X, Wang D, Pan C, Weber PK, Jiang J, Zhou J, Zhang Y, Stahl DA, Ward BB, Mayali X, Martens-Habbena W, Winkler MKH. Ammonia-oxidizing bacteria and archaea exhibit differential nitrogen source preferences. Nat Microbiol 2024; 9:524-536. [PMID: 38297167 DOI: 10.1038/s41564-023-01593-7] [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: 07/25/2023] [Accepted: 12/15/2023] [Indexed: 02/02/2024]
Abstract
Ammonia-oxidizing microorganisms (AOM) contribute to one of the largest nitrogen fluxes in the global nitrogen budget. Four distinct lineages of AOM: ammonia-oxidizing archaea (AOA), beta- and gamma-proteobacterial ammonia-oxidizing bacteria (β-AOB and γ-AOB) and complete ammonia oxidizers (comammox), are thought to compete for ammonia as their primary nitrogen substrate. In addition, many AOM species can utilize urea as an alternative energy and nitrogen source through hydrolysis to ammonia. How the coordination of ammonia and urea metabolism in AOM influences their ecology remains poorly understood. Here we use stable isotope tracing, kinetics and transcriptomics experiments to show that representatives of the AOM lineages employ distinct regulatory strategies for ammonia or urea utilization, thereby minimizing direct substrate competition. The tested AOA and comammox species preferentially used ammonia over urea, while β-AOB favoured urea utilization, repressed ammonia transport in the presence of urea and showed higher affinity for urea than for ammonia. Characterized γ-AOB co-utilized both substrates. These results reveal contrasting niche adaptation and coexistence patterns among the major AOM lineages.
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Affiliation(s)
- Wei Qin
- School of Biological Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, USA.
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA.
| | - Stephany P Wei
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
| | - Yue Zheng
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, China
| | - Eunkyung Choi
- Department of Microbiology and Cell Science, Fort Lauderdale Research and Education Center, University of Florida, Davie, FL, USA
| | - Xiangpeng Li
- School of Biological Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, USA
| | | | - Xianhui Wan
- Department of Geosciences, Princeton University, Princeton, NJ, USA
| | - Britt Abrahamson
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
| | - Zachary Flinkstrom
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
| | - Baozhan Wang
- College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Hanyan Li
- School of Biological Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, USA
| | - Lei Hou
- School of Biological Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, USA
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, China
| | - Qing Tao
- School of Biological Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, USA
| | - Wyatt W Chlouber
- School of Biological Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, USA
| | - Xin Sun
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA
| | - Michael Wells
- School of Biological Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, USA
| | - Long Ngo
- School of Biological Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, USA
| | - Kristopher A Hunt
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
| | - Hidetoshi Urakawa
- Department of Ecology and Environmental Studies, Florida Gulf Coast University, Fort Myers, FL, USA
| | - Xuanyu Tao
- School of Biological Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, USA
| | - Dongyu Wang
- School of Biological Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, USA
| | - Xiaoyuan Yan
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Dazhi Wang
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, China
| | - Chongle Pan
- School of Biological Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, USA
| | - Peter K Weber
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Jiandong Jiang
- College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Jizhong Zhou
- School of Biological Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, USA
| | - Yao Zhang
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
| | - David A Stahl
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
| | - Bess B Ward
- Department of Geosciences, Princeton University, Princeton, NJ, USA
| | - Xavier Mayali
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Willm Martens-Habbena
- Department of Microbiology and Cell Science, Fort Lauderdale Research and Education Center, University of Florida, Davie, FL, USA.
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4
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Williamson G, Bizior A, Harris T, Pritchard L, Hoskisson P, Javelle A. Biological ammonium transporters from the Amt/Mep/Rh superfamily: mechanism, energetics, and technical limitations. Biosci Rep 2024; 44:BSR20211209. [PMID: 38131184 PMCID: PMC10794816 DOI: 10.1042/bsr20211209] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 12/12/2023] [Accepted: 12/21/2023] [Indexed: 12/23/2023] Open
Abstract
The exchange of ammonium across cellular membranes is a fundamental process in all domains of life and is facilitated by the ubiquitous Amt/Mep/Rh transporter superfamily. Remarkably, despite a high structural conservation in all domains of life, these proteins have gained various biological functions during evolution. It is tempting to hypothesise that the physiological functions gained by these proteins may be explained at least in part by differences in the energetics of their translocation mechanisms. Therefore, in this review, we will explore our current knowledge of energetics of the Amt/Mep/Rh family, discuss variations in observations between different organisms, and highlight some technical drawbacks which have hampered effects at mechanistic characterisation. Through the review, we aim to provide a comprehensive overview of current understanding of the mechanism of transport of this unique and extraordinary Amt/Mep/Rh superfamily of ammonium transporters.
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Affiliation(s)
- Gordon Williamson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, U.K
| | - Adriana Bizior
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, U.K
| | - Thomas Harris
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, U.K
| | - Leighton Pritchard
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, U.K
| | - Paul A. Hoskisson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, U.K
| | - Arnaud Javelle
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, U.K
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5
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Williamson G, Harris T, Bizior A, Hoskisson PA, Pritchard L, Javelle A. Biological ammonium transporters: evolution and diversification. FEBS J 2024. [PMID: 38265636 DOI: 10.1111/febs.17059] [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: 09/26/2023] [Revised: 12/14/2023] [Accepted: 01/09/2024] [Indexed: 01/25/2024]
Abstract
Although ammonium is the preferred nitrogen source for microbes and plants, in animal cells it is a toxic product of nitrogen metabolism that needs to be excreted. Thus, ammonium movement across biological membranes, whether for uptake or excretion, is a fundamental and ubiquitous biological process catalysed by the superfamily of the Amt/Mep/Rh transporters. A remarkable feature of the Amt/Mep/Rh family is that they are ubiquitous and, despite sharing low amino acid sequence identity, are highly structurally conserved. Despite sharing a common structure, these proteins have become involved in a diverse range of physiological process spanning all domains of life, with reports describing their involvement in diverse biological processes being published regularly. In this context, we exhaustively present their range of biological roles across the domains of life and after explore current hypotheses concerning their evolution to help to understand how and why the conserved structure fulfils diverse physiological functions.
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Affiliation(s)
- Gordon Williamson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Thomas Harris
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Adriana Bizior
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Paul Alan Hoskisson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Leighton Pritchard
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Arnaud Javelle
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
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6
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Habenicht T, Weidenbach K, Velazquez-Campoy A, Buey RM, Balsera M, Schmitz RA. Small protein mediates inhibition of ammonium transport in Methanosarcina mazei-an ancient mechanism? Microbiol Spectr 2023; 11:e0281123. [PMID: 37909787 PMCID: PMC10714827 DOI: 10.1128/spectrum.02811-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 09/29/2023] [Indexed: 11/03/2023] Open
Abstract
IMPORTANCE Small proteins containing fewer than 70 amino acids, which were previously disregarded due to computational prediction and biochemical detection challenges, have gained increased attention in the scientific community in recent years. However, the number of functionally characterized small proteins, especially in archaea, is still limited. Here, by using biochemical and genetic approaches, we demonstrate a crucial role of the small protein sP36 in the nitrogen metabolism of M. mazei, which modulates the ammonium transporter AmtB1 according to nitrogen availability. This modulation might represent an ancient archaeal mechanism of AmtB1 inhibition, in contrast to the well-studied uridylylation-dependent regulation in bacteria.
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Affiliation(s)
- Tim Habenicht
- Institut für allgemeine Mikrobiologie, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Katrin Weidenbach
- Institut für allgemeine Mikrobiologie, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Adrian Velazquez-Campoy
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Universidad de Zaragoza, Zaragoza, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
- Instituto de Investigaciones Sanitarias de Aragón (IIS Aragón), Zaragoza, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Madrid, Spain
| | - Ruben M. Buey
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Monica Balsera
- Instituto de Recursos Naturales y Agrobiología de Salamanca, Spanish National Research Council (IRNASA-CSIC), Salamanca, Spain
| | - Ruth A. Schmitz
- Institut für allgemeine Mikrobiologie, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
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7
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Jordan B, Weidenbach K, Schmitz RA. The power of the small: the underestimated role of small proteins in bacterial and archaeal physiology. Curr Opin Microbiol 2023; 76:102384. [PMID: 37776678 DOI: 10.1016/j.mib.2023.102384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/04/2023] [Accepted: 09/04/2023] [Indexed: 10/02/2023]
Abstract
Small proteins encoded by small open-reading frames (sORFs) (≤70 aa) were overlooked for decades due to methodological reasons and are thus often missing in genome annotations. Novel detection methods such as ribosome profiling (Ribo-Seq) and mass spectrometry optimized for small proteins (peptidomics) have opened up a new field of interest and several catalogs of small proteins in bacteria and archaea have been recently reported. Many translated sORFs have been discovered in genomic locations previously thought to be noncoding, such as 5' or 3' untranslated regions or well-studied regulatory small RNAs (sRNAs). Even within longer ORFs, additional functional sORFs have been detected. Today, only a small proportion is characterized, but those small proteins indicate important and diverse functions in cellular physiology. Here, we summarize recently characterized small proteins involved in microbial metabolism.
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Affiliation(s)
- Britta Jordan
- Institute for General Microbiology, Christian-Albrechts-University, 24118 Kiel, Germany
| | - Katrin Weidenbach
- Institute for General Microbiology, Christian-Albrechts-University, 24118 Kiel, Germany
| | - Ruth A Schmitz
- Institute for General Microbiology, Christian-Albrechts-University, 24118 Kiel, Germany.
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8
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Wright CL, Lehtovirta-Morley LE. Nitrification and beyond: metabolic versatility of ammonia oxidising archaea. THE ISME JOURNAL 2023; 17:1358-1368. [PMID: 37452095 PMCID: PMC10432482 DOI: 10.1038/s41396-023-01467-0] [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: 12/20/2022] [Revised: 06/09/2023] [Accepted: 06/21/2023] [Indexed: 07/18/2023]
Abstract
Ammonia oxidising archaea are among the most abundant living organisms on Earth and key microbial players in the global nitrogen cycle. They carry out oxidation of ammonia to nitrite, and their activity is relevant for both food security and climate change. Since their discovery nearly 20 years ago, major insights have been gained into their nitrogen and carbon metabolism, growth preferences and their mechanisms of adaptation to the environment, as well as their diversity, abundance and activity in the environment. Despite significant strides forward through the cultivation of novel organisms and omics-based approaches, there are still many knowledge gaps on their metabolism and the mechanisms which enable them to adapt to the environment. Ammonia oxidising microorganisms are typically considered metabolically streamlined and highly specialised. Here we review the physiology of ammonia oxidising archaea, with focus on aspects of metabolic versatility and regulation, and discuss these traits in the context of nitrifier ecology.
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Affiliation(s)
- Chloe L Wright
- School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, United Kingdom
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9
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Carter MS, Tuttle MJ, Mancini JA, Martineau R, Hung CS, Gupta MK. Microbially Induced Calcium Carbonate Precipitation by Sporosarcina pasteurii: a Case Study in Optimizing Biological CaCO 3 Precipitation. Appl Environ Microbiol 2023; 89:e0179422. [PMID: 37439668 PMCID: PMC10467343 DOI: 10.1128/aem.01794-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2023] Open
Abstract
Current production of traditional concrete requires enormous energy investment that accounts for approximately 5 to 8% of the world's annual CO2 production. Biocement is a building material that is already in industrial use and has the potential to rival traditional concrete as a more convenient and more environmentally friendly alternative. Biocement relies on biological structures (enzymes, cells, and/or cellular superstructures) to mineralize and bind particles in aggregate materials (e.g., sand and soil particles). Sporosarcina pasteurii is a workhorse organism for biocementation, but most research to date has focused on S. pasteurii as a building material rather than a biological system. In this review, we synthesize available materials science, microbiology, biochemistry, and cell biology evidence regarding biological CaCO3 precipitation and the role of microbes in microbially induced calcium carbonate precipitation (MICP) with a focus on S. pasteurii. Based on the available information, we provide a model that describes the molecular and cellular processes involved in converting feedstock material (urea and Ca2+) into cement. The model provides a foundational framework that we use to highlight particular targets for researchers as they proceed into optimizing the biology of MICP for biocement production.
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Affiliation(s)
- Michael S. Carter
- Materials and Manufacturing Directorate Air Force Research Lab, Wright-Patterson Air Force Base, Dayton, Ohio, USA
- Biological and Nanoscale Technologies Division, UES, Inc., Dayton, Ohio, USA
| | - Matthew J. Tuttle
- Materials and Manufacturing Directorate Air Force Research Lab, Wright-Patterson Air Force Base, Dayton, Ohio, USA
- Biological and Nanoscale Technologies Division, UES, Inc., Dayton, Ohio, USA
| | - Joshua A. Mancini
- Materials and Manufacturing Directorate Air Force Research Lab, Wright-Patterson Air Force Base, Dayton, Ohio, USA
- Biological and Nanoscale Technologies Division, UES, Inc., Dayton, Ohio, USA
| | - Rhett Martineau
- Materials and Manufacturing Directorate Air Force Research Lab, Wright-Patterson Air Force Base, Dayton, Ohio, USA
- Biological and Nanoscale Technologies Division, UES, Inc., Dayton, Ohio, USA
| | - Chia-Suei Hung
- Materials and Manufacturing Directorate Air Force Research Lab, Wright-Patterson Air Force Base, Dayton, Ohio, USA
| | - Maneesh K. Gupta
- Materials and Manufacturing Directorate Air Force Research Lab, Wright-Patterson Air Force Base, Dayton, Ohio, USA
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10
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Bizior A, Williamson G, Harris T, Hoskisson PA, Javelle A. Prokaryotic ammonium transporters: what has three decades of research revealed? MICROBIOLOGY (READING, ENGLAND) 2023; 169:001360. [PMID: 37450375 PMCID: PMC10433425 DOI: 10.1099/mic.0.001360] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 06/24/2023] [Indexed: 07/18/2023]
Abstract
The exchange of ammonium across cellular membranes is a fundamental process in all domains of life. In plants, bacteria and fungi, ammonium represents a vital source of nitrogen, which is scavenged from the external environment. In contrast, in animal cells ammonium is a cytotoxic metabolic waste product and must be excreted to prevent cell death. Transport of ammonium is facilitated by the ubiquitous Amt/Mep/Rh transporter superfamily. In addition to their function as transporters, Amt/Mep/Rh proteins play roles in a diverse array of biological processes and human physiopathology. Despite this clear physiological importance and medical relevance, the molecular mechanism of Amt/Mep/Rh proteins has remained elusive. Crystal structures of bacterial Amt/Rh proteins suggest electroneutral transport, whilst functional evidence supports an electrogenic mechanism. Here, focusing on bacterial members of the family, we summarize the structure of Amt/Rh proteins and what three decades of research tells us concerning the general mechanisms of ammonium translocation, in particular the possibility that the transport mechanism might differ in various members of the Amt/Mep/Rh superfamily.
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Affiliation(s)
- Adriana Bizior
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, UK
| | - Gordon Williamson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, UK
| | - Thomas Harris
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, UK
| | - Paul A. Hoskisson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, UK
| | - Arnaud Javelle
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, UK
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11
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Hu C, Dai W, Zhu X, Yao H, Lin Z, Dong Y, Lv L. Expression and Functional Analysis of AMT1 Gene Responding to High Ammonia Stress in Razor Clam ( Sinonovacula constricta). Animals (Basel) 2023; 13:ani13101638. [PMID: 37238069 DOI: 10.3390/ani13101638] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/01/2023] [Accepted: 05/11/2023] [Indexed: 05/28/2023] Open
Abstract
Ammonium transporter 1 (AMT1), a member of ammonia (NH3/NH4+) transport proteins, has been found to have ammonia transport activity in plants and microorganisms. However, the functional characteristics and molecular mechanisms of AMT1 in mollusks remain unclear. The razor clam (Sinonovacula constricta) is a suitable model species to explore the molecular mechanism of ammonia excretion because of the high concentration of ambient ammonia it is exposed to in the clam-fish-shrimp polyculture system. Here, the expression of AMT1 in S. constricta (Sc-AMT1) in response to high ammonia (12.85 mmol/L NH4Cl) stress was identified by real-time quantitative PCR (qRT-PCR), Western blotting, RNA interference, and immunofluorescence analysis. Additionally, the association between the SNP_g.15211125A > T linked with Sc-AMT1 and ammonia tolerance was validated by kompetitive allele-specific PCR (KASP). A significant upregulated expression of Sc-AMT1 was observed during ammonia exposure, and Sc-AMT1 was found to be localized in the flat cells of gill. Moreover, the interference with Sc-AMT1 significantly upregulated the hemolymph ammonia levels, accompanied by the increased mRNA expression of Rhesus glycoprotein (Rh). Taken together, our findings imply that AMT1 may be a primary contributor to ammonia excretion in S. constricta, which is the basis of their ability to inhabit benthic water with high ammonia levels.
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Affiliation(s)
- Chenxin Hu
- Key Laboratory of Aquatic Germplasm Resource of Zhejiang, College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo 315100, China
| | - Wenfang Dai
- Ninghai Institute of Mariculture Breeding and Seed Industry, Zhejiang Wanli University, Ningbo 315604, China
| | - Xiaojie Zhu
- Key Laboratory of Aquatic Germplasm Resource of Zhejiang, College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo 315100, China
| | - Hanhan Yao
- Key Laboratory of Aquatic Germplasm Resource of Zhejiang, College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo 315100, China
| | - Zhihua Lin
- Key Laboratory of Aquatic Germplasm Resource of Zhejiang, College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo 315100, China
- Ninghai Institute of Mariculture Breeding and Seed Industry, Zhejiang Wanli University, Ningbo 315604, China
| | - Yinghui Dong
- Ninghai Institute of Mariculture Breeding and Seed Industry, Zhejiang Wanli University, Ningbo 315604, China
| | - Liyuan Lv
- Ninghai Institute of Mariculture Breeding and Seed Industry, Zhejiang Wanli University, Ningbo 315604, China
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Densi A, Iyer RS, Bhat PJ. Synonymous and Nonsynonymous Substitutions in Dictyostelium discoideum Ammonium Transporter amtA Are Necessary for Functional Complementation in Saccharomyces cerevisiae. Microbiol Spectr 2023; 11:e0384722. [PMID: 36840598 PMCID: PMC10100761 DOI: 10.1128/spectrum.03847-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 01/24/2023] [Indexed: 02/24/2023] Open
Abstract
Ammonium transporters are present in all three domains of life. They have undergone extensive horizontal gene transfer (HGT), gene duplication, and functional diversification and therefore offer an excellent paradigm to study protein evolution. We attempted to complement a mep1Δmep2Δmep3Δ strain of Saccharomyces cerevisiae (triple-deletion strain), which otherwise cannot grow on ammonium as a sole nitrogen source at concentrations of <3 mM, with amtA of Dictyostelium discoideum, an orthologue of S. cerevisiae MEP2. We observed that amtA did not complement the triple-deletion strain of S. cerevisiae for growth on low-ammonium medium. We isolated two mutant derivatives of amtA (amtA M1 and amtA M2) from a PCR-generated mutant plasmid library that complemented the triple-deletion strain of S. cerevisiae. amtA M1 bears three nonsynonymous and two synonymous substitutions, which are necessary for its functionality. amtA M2 bears two nonsynonymous substitutions and one synonymous substitution, all of which are necessary for functionality. Interestingly, AmtA M1 transports ammonium but does not confer methylamine toxicity, while AmtA M2 transports ammonium and confers methylamine toxicity, demonstrating functional diversification. Preliminary biochemical analyses indicated that the mutants differ in their conformations as well as their mechanisms of ammonium transport. These intriguing results clearly point out that protein evolution cannot be fathomed by studying nonsynonymous and synonymous substitutions in isolation. The above-described observations have significant implications for various facets of biological processes and are discussed in detail. IMPORTANCE Functional diversification following gene duplication is one of the major driving forces of protein evolution. While the role of nonsynonymous substitutions in the functional diversification of proteins is well recognized, knowledge of the role of synonymous substitutions in protein evolution is in its infancy. Using functional complementation, we isolated two functional alleles of the D. discoideum ammonium transporter gene (amtA), which otherwise does not function in S. cerevisiae as an ammonium transporters. One of them is an ammonium transporter, while the other is an ammonium transporter that also confers methylammonium (ammonium analogue) toxicity, suggesting functional diversification. Surprisingly, both alleles require a combination of synonymous and nonsynonymous substitutions for their functionality. These results bring out a hitherto-unknown pathway of protein evolution and pave the way for not only understanding protein evolution but also interpreting single nucleotide polymorphisms (SNPs).
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Affiliation(s)
- Asha Densi
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Revathi S. Iyer
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Paike Jayadeva Bhat
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
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13
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Li Z, Zhu M, Huang J, Jiang S, Xu S, Zhang Z, He W, Huang W. Genome-Wide Comprehensive Analysis of the Nitrogen Metabolism Toolbox Reveals Its Evolution and Abiotic Stress Responsiveness in Rice ( Oryza sativa L.). Int J Mol Sci 2022; 24:ijms24010288. [PMID: 36613735 PMCID: PMC9820731 DOI: 10.3390/ijms24010288] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 12/19/2022] [Accepted: 12/20/2022] [Indexed: 12/28/2022] Open
Abstract
Nitrogen metabolism (NM) plays an essential role in response to abiotic stresses for plants. Enzyme activities have been extensively studied for nitrogen metabolism-associated pathways, but the knowledge of nitrogen metabolism-associated genes involved in stress response is still limited, especially for rice. In this study, we performed the genome-wide characterization of the genes putatively involved in nitrogen metabolism. A total of 1110 potential genes were obtained to be involved in nitrogen metabolism from eight species (Arabidopsis thaliana (L.) Heynh., Glycine max (L.) Merr., Brassica napus L., Triticum aestivum L., Sorghum bicolor L., Zea mays L., Oryza sativa L. and Amborella trichopoda Baill.), especially 104 genes in rice. The comparative phylogenetic analysis of the superfamily revealed the complicated divergence of different NM genes. The expression analysis among different tissues in rice indicates the NM genes showed diverse functions in the pathway of nitrogen absorption and assimilation. Distinct expression patterns of NM genes were observed in rice under drought stress, heat stress, and salt stress, indicating that the NM genes play a curial role in response to abiotic stress. Most NM genes showed a down-regulated pattern under heat stress, while complicated expression patterns were observed for different genes under salt stress and drought stress. The function of four representative NM genes (OsGS2, OsGLU, OsGDH2, and OsAMT1;1) was further validated by using qRT-PCR analysis to confirm their responses to these abiotic stresses. Based on the predicted transcription factor binding sites (TFBSs), we built a co-expression regulatory network containing transcription factors (TFs) and NM genes, of which the constructed ERF and Dof genes may act as the core genes to respond to abiotic stresses. This study provides novel sights to the interaction between nitrogen metabolism and the response to abiotic stresses.
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Affiliation(s)
- Zhihui Li
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Mingqiang Zhu
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Jinqiu Huang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Shan Jiang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Shuang Xu
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Zhihong Zhang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Wenchuang He
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
- Correspondence: (W.H.); (W.H.); Tel.: +86-137-2030-6240 (W.H.); +86-189-0711-8608 (W.H.)
| | - Wenchao Huang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
- Correspondence: (W.H.); (W.H.); Tel.: +86-137-2030-6240 (W.H.); +86-189-0711-8608 (W.H.)
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14
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Kellom M, Pagliara S, Richards TA, Santoro AE. Exaggerated trans-membrane charge of ammonium transporters in nutrient-poor marine environments. Open Biol 2022; 12:220041. [PMID: 35857930 PMCID: PMC9277239 DOI: 10.1098/rsob.220041] [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] [Indexed: 12/25/2022] Open
Abstract
Transporter proteins are a vital interface between cells and their environment. In nutrient-limited environments, microbes with transporters that are effective at bringing substrates into their cells will gain a competitive advantage over variants with reduced transport function. Microbial ammonium transporters (Amt) bring ammonium into the cytoplasm from the surrounding periplasm space, but diagnosing Amt adaptations to low nutrient environments solely from sequence data has been elusive. Here, we report altered Amt sequence amino acid distribution from deep marine samples compared to variants sampled from shallow water in two important microbial lineages of the marine water column community-Marine Group I Archaea (Thermoproteota) and the uncultivated gammaproteobacterial lineage SAR86. This pattern indicates an evolutionary pressure towards an increasing dipole in Amt for these clades in deep ocean environments and is predicted to generate stronger electric fields facilitating ammonium acquisition. This pattern of increasing dipole charge with depth was not observed in lineages capable of accessing alternative nitrogen sources, including the abundant alphaproteobacterial clade SAR11. We speculate that competition for ammonium in the deep ocean drives transporter sequence evolution. The low concentration of ammonium in the deep ocean is therefore likely due to rapid uptake by Amts concurrent with decreasing nutrient flux.
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Affiliation(s)
- Matthew Kellom
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA, USA
| | - Stefano Pagliara
- Living Systems Institute and Biosciences, University of Exeter, Exeter, Devon EX4 4QD, UK
| | - Thomas A. Richards
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
| | - Alyson E. Santoro
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA, USA
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15
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Phylogenomic Analysis of Metagenome-Assembled Genomes Deciphered Novel Acetogenic Nitrogen-Fixing Bathyarchaeota from Hot Spring Sediments. Microbiol Spectr 2022; 10:e0035222. [PMID: 35647693 PMCID: PMC9241837 DOI: 10.1128/spectrum.00352-22] [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] [Indexed: 11/20/2022] Open
Abstract
This study describes the phylogenomic analysis and metabolic insights of metagenome-assembled genomes (MAGs) retrieved from hot spring sediment samples. The metagenome-assembled sequences recovered three near-complete genomes belonging to the archaeal phylum. Analysis of genome-wide core genes and 16S rRNA-based phylogeny placed the ILS200 and ILS300 genomes within the uncultivated and largely understudied bathyarchaeal phylum, whereas ILS100 represented the phylum Thaumarchaeota. The average nucleotide identity (ANI) of the bin ILS100 was 76% with Nitrososphaeria_archaeon_isolate_SpSt-1069. However, the bins ILS200 and ILS300 showed ANI values of 75% and 70% with Candidatus_Bathyarchaeota_archaeon_isolate_DRTY-6_2_bin_115 and Candidatus_Bathyarchaeota_archaeon_BA1_ba1_01, respectively. The genomic potential of Bathyarchaeota bins ILS200 and ILS300 showed genes necessary for the Wood-Ljungdahl pathway, and the gene encoding the methyl coenzyme M reductase (mcr) complex essential for methanogenesis was absent. The metabolic potential of the assembled genomes included genes involved in nitrogen assimilation, including nitrogenase and the genes necessary for the urea cycle. The presence of these genes suggested the metabolic potential of Bathyarchaeota to fix nitrogen under extreme environments. In addition, the ILS200 and ILS300 genomes carried genes involved in the tricarboxylic acid (TCA) cycle, glycolysis, and degradation of organic carbons. Finally, we conclude that the reconstructed Bathyarchaeota bins are autotrophic acetogens and organo-heterotrophs. IMPORTANCE We describe the Bathyarchaeota bins that are likely to be acetogens with a wide range of metabolic potential. These bins did not exhibit methanogenic machinery, suggesting methane production may not occur by all subgroup lineages of Bathyarchaeota. Phylogenetic analysis support that both ILS200 and ILS300 belonged to the Bathyarchaeota. The discovery of new bathyarchaeotal MAGs provides additional knowledge for understanding global carbon and nitrogen metabolism under extreme conditions.
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16
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Coexistence of Ammonium Transporter and Channel Mechanisms in Amt-Mep-Rh Twin-His Variants Impairs the Filamentation Signaling Capacity of Fungal Mep2 Transceptors. mBio 2022; 13:e0291321. [PMID: 35196127 PMCID: PMC9040831 DOI: 10.1128/mbio.02913-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Ammonium translocation through biological membranes, by the ubiquitous Amt-Mep-Rh family of transporters, plays a key role in all domains of life. Two highly conserved histidine residues protrude into the lumen of the pore of these transporters, forming the family’s characteristic Twin-His motif. It has been hypothesized that the motif is essential to confer the selectivity of the transport mechanism. Here, using a combination of in vitro electrophysiology on Escherichia coli AmtB, in silico molecular dynamics simulations, and in vivo yeast functional complementation assays, we demonstrate that variations in the Twin-His motif trigger a mechanistic switch between a specific transporter, depending on ammonium deprotonation, to an unspecific ion channel activity. We therefore propose that there is no selective filter that governs specificity in Amt-Mep-Rh transporters, but the inherent mechanism of translocation, dependent on the fragmentation of the substrate, ensures the high specificity of the translocation. We show that coexistence of both mechanisms in single Twin-His variants of yeast Mep2 transceptors disrupts the signaling function and so impairs fungal filamentation. These data support a signaling process driven by the transport mechanism of the fungal Mep2 transceptors.
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17
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Andrei A, Di Renzo MA, Öztürk Y, Meisner A, Daum N, Frank F, Rauch J, Daldal F, Andrade SLA, Koch HG. The CopA2-Type P 1B-Type ATPase CcoI Serves as Central Hub for cbb 3-Type Cytochrome Oxidase Biogenesis. Front Microbiol 2021; 12:712465. [PMID: 34589071 PMCID: PMC8475189 DOI: 10.3389/fmicb.2021.712465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 07/12/2021] [Indexed: 11/13/2022] Open
Abstract
Copper (Cu)-transporting P1B-type ATPases are ubiquitous metal transporters and crucial for maintaining Cu homeostasis in all domains of life. In bacteria, the P1B-type ATPase CopA is required for Cu-detoxification and exports excess Cu(I) in an ATP-dependent reaction from the cytosol into the periplasm. CopA is a member of the CopA1-type ATPase family and has been biochemically and structurally characterized in detail. In contrast, less is known about members of the CopA2-type ATPase family, which are predicted to transport Cu(I) into the periplasm for cuproprotein maturation. One example is CcoI, which is required for the maturation of cbb 3-type cytochrome oxidase (cbb 3-Cox) in different species. Here, we reconstituted purified CcoI of Rhodobacter capsulatus into liposomes and determined Cu transport using solid-supported membrane electrophysiology. The data demonstrate ATP-dependent Cu(I) translocation by CcoI, while no transport is observed in the presence of a non-hydrolysable ATP analog. CcoI contains two cytosolically exposed N-terminal metal binding sites (N-MBSs), which are both important, but not essential for Cu delivery to cbb 3-Cox. CcoI and cbb 3-Cox activity assays in the presence of different Cu concentrations suggest that the glutaredoxin-like N-MBS1 is primarily involved in regulating the ATPase activity of CcoI, while the CopZ-like N-MBS2 is involved in Cu(I) acquisition. The interaction of CcoI with periplasmic Cu chaperones was analyzed by genetically fusing CcoI to the chaperone SenC. The CcoI-SenC fusion protein was fully functional in vivo and sufficient to provide Cu for cbb 3-Cox maturation. In summary, our data demonstrate that CcoI provides the link between the cytosolic and periplasmic Cu chaperone networks during cbb 3-Cox assembly.
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Affiliation(s)
- Andreea Andrei
- Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany.,Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Maria Agostina Di Renzo
- Institute for Biochemistry, Faculty of Chemistry and Pharmacy, Albert-Ludwigs-University Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany.,Faculty of Chemistry and Pharmacy, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Yavuz Öztürk
- Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Alexandra Meisner
- Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Noel Daum
- Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Fabian Frank
- Institute for Biochemistry, Faculty of Chemistry and Pharmacy, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Juna Rauch
- Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Fevzi Daldal
- Department of Biology, University of Pennsylvania, Philadelphia, PA, United States
| | - Susana L A Andrade
- Institute for Biochemistry, Faculty of Chemistry and Pharmacy, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Hans-Georg Koch
- Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
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18
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The Oxoglutarate Binding Site and Regulatory Mechanism Are Conserved in Ammonium Transporter Inhibitors GlnKs from Methanococcales. Int J Mol Sci 2021; 22:ijms22168631. [PMID: 34445335 PMCID: PMC8395244 DOI: 10.3390/ijms22168631] [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: 07/15/2021] [Revised: 08/04/2021] [Accepted: 08/05/2021] [Indexed: 11/16/2022] Open
Abstract
Protein inhibition is a natural regulatory process to control cellular metabolic fluxes. PII-family signal-transducing effectors are in this matter key regulators of the nitrogen metabolism. Their interaction with their various targets is governed by the cellular nitrogen level and the energy charge. Structural studies on GlnK, a PII-family inhibitor of the ammonium transporters (Amt), showed that the T-loops responsible for channel obstruction are displaced upon the binding of 2-oxoglutarate, magnesium and ATP in a conserved cleft. However, GlnK from Methanocaldococcus jannaschii was shown to bind 2-oxoglutarate on the tip of its T-loop, causing a moderate disruption to GlnK-Amt interaction, raising the question if methanogenic archaea use a singular adaptive strategy. Here we show that membrane fractions of Methanothermococcus thermolithotrophicus released GlnKs only in the presence of Mg-ATP and 2-oxoglutarate. This observation led us to structurally characterize the two GlnK isoforms apo or in complex with ligands. Together, our results show that the 2-oxoglutarate binding interface is conserved in GlnKs from Methanococcales, including Methanocaldococcus jannaschii, emphasizing the importance of a free carboxy-terminal group to facilitate ligand binding and to provoke the shift of the T-loop positions.
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19
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Vulpe A, Kim HS, Ballou S, Wu ST, Grabe V, Nava Gonzales C, Liang T, Sachse S, Jeanne JM, Su CY, Menuz K. An ammonium transporter is a non-canonical olfactory receptor for ammonia. Curr Biol 2021; 31:3382-3390.e7. [PMID: 34111404 PMCID: PMC8355169 DOI: 10.1016/j.cub.2021.05.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 04/18/2021] [Accepted: 05/13/2021] [Indexed: 10/21/2022]
Abstract
Numerous hematophagous insects are attracted to ammonia, a volatile released in human sweat and breath.1-3 Low levels of ammonia also attract non-biting insects such as the genetic model organism Drosophila melanogaster and several species of agricultural pests.4,5 Two families of ligand-gated ion channels function as olfactory receptors in insects,6-10 and studies have linked ammonia sensitivity to a particular olfactory receptor in Drosophila.5,11,12 Given the widespread importance of ammonia to insect behavior, it is surprising that the genomes of most insects lack an ortholog of this gene.6 Here, we show that canonical olfactory receptors are not necessary for responses to ammonia in Drosophila. Instead, we demonstrate that a member of the ancient electrogenic ammonium transporter family, Amt, is likely a new type of olfactory receptor. We report two hitherto unidentified olfactory neuron populations that mediate neuronal and behavioral responses to ammonia in Drosophila. Their endogenous ammonia responses are lost in Amt mutant flies, and ectopic expression of either Drosophila or Anopheles Amt confers ammonia sensitivity. These results suggest that Amt is the first transporter known to function as an olfactory receptor in animals and that its function may be conserved across insect species.
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Affiliation(s)
- Alina Vulpe
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269, USA
| | - Hyong S Kim
- Department of Neuroscience, Yale University, New Haven, CT 06510, USA
| | - Sydney Ballou
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269, USA
| | - Shiuan-Tze Wu
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Veit Grabe
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena 07745, Germany
| | - Cesar Nava Gonzales
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Tiffany Liang
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269, USA
| | - Silke Sachse
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena 07745, Germany
| | - James M Jeanne
- Department of Neuroscience, Yale University, New Haven, CT 06510, USA
| | - Chih-Ying Su
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Karen Menuz
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269, USA; Connecticut Institute for Brain and Cognitive Sciences, University of Connecticut, Storrs, CT 06269, USA.
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Abstract
Cell membranes - primarily composed of lipids, sterols, and proteins - form a dynamic interface between living cells and their environment. They act as a mechanical barrier around the cell while selectively facilitating material transport, signal transduction, and various other functions necessary for the cell viability. The complex functionality of cell membranes and the hierarchical motions and responses they exhibit demand a thorough understanding of the origin of different membrane dynamics and how they are influenced by molecular additives and environmental cues. These dynamic modes include single-molecule diffusion, thermal fluctuations, and large-scale membrane deformations, to name a few. This review highlights advances in investigating structure-driven dynamics associated with model cell membranes, with a particular focus on insights gained from neutron scattering and spectroscopy experiments. We discuss the uniqueness of neutron contrast variation and its remarkable potential in probing selective membrane structure and dynamics on spatial and temporal scales over which key biological functions occur. We also present a summary of current and future opportunities in synergistic combinations of neutron scattering with molecular dynamics (MD) simulations to gain further understanding of the molecular mechanisms underlying complex membrane functions.
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Affiliation(s)
- Sudipta Gupta
- Department of Physics, Virginia Tech, Blacksburg, VA 24061, USA. and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA 24061, USA
| | - Rana Ashkar
- Department of Physics, Virginia Tech, Blacksburg, VA 24061, USA. and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA 24061, USA
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21
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In Escherichia coli Ammonia Inhibits Cytochrome bo3 But Activates Cytochrome bd-I. Antioxidants (Basel) 2020; 10:antiox10010013. [PMID: 33375541 PMCID: PMC7824442 DOI: 10.3390/antiox10010013] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/18/2020] [Accepted: 12/21/2020] [Indexed: 12/14/2022] Open
Abstract
Interaction of two redox enzymes of Escherichia coli, cytochrome bo3 and cytochrome bd-I, with ammonium sulfate/ammonia at pH 7.0 and 8.3 was studied using high-resolution respirometry and absorption spectroscopy. At pH 7.0, the oxygen reductase activity of none of the enzymes is affected by the ligand. At pH 8.3, cytochrome bo3 is inhibited by the ligand, with 40% maximum inhibition at 100 mM (NH4)2SO4. In contrast, the activity of cytochrome bd-I at pH 8.3 increases with increasing the ligand concentration, the largest increase (140%) is observed at 100 mM (NH4)2SO4. In both cases, the effector molecule is apparently not NH4+ but NH3. The ligand induces changes in absorption spectra of both oxidized cytochromes at pH 8.3. The magnitude of these changes increases as ammonia concentration is increased, yielding apparent dissociation constants Kdapp of 24.3 ± 2.7 mM (NH4)2SO4 (4.9 ± 0.5 mM NH3) for the Soret region in cytochrome bo3, and 35.9 ± 7.1 and 24.6 ± 12.4 mM (NH4)2SO4 (7.2 ± 1.4 and 4.9 ± 2.5 mM NH3) for the Soret and visible regions, respectively, in cytochrome bd-I. Consistently, addition of (NH4)2SO4 to cells of the E. coli mutant containing cytochrome bd-I as the only terminal oxidase at pH 8.3 accelerates the O2 consumption rate, the highest one (140%) being at 27 mM (NH4)2SO4. We discuss possible molecular mechanisms and physiological significance of modulation of the enzymatic activities by ammonia present at high concentration in the intestines, a niche occupied by E. coli.
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Abstract
AbstractIt is crucial for the growth and development of an organism whether ammonium is transported across its membranes in a form of NH4+ or NH3. The transport of both molecules follows different pH-dependent gradients across membranes and transport of both substrates differentially affects the internal and external pH. As a consequence, they directly influence the physiology and organism development. CaMep2 from Candida albicans shows a dual transceptor function in ammonium transport and sensing. CaMep2 senses low ammonium availability and induces filamentous growth. CaMep1, by contrast, is only active in transport, but not involved in ammonium signaling. Here, both proteins were heterologously expressed in Xenopus laevis oocytes. This study identified electrogenic NH4+ transport by CaMep1 and electroneutral NH3 transport by CaMep2, which might be a prerequisite for the induction of pseudohyphal growth.
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23
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Smeulders MJ, Peeters SH, van Alen T, de Bruijckere D, Nuijten GHL, op den Camp HJM, Jetten MSM, van Niftrik L. Nutrient Limitation Causes Differential Expression of Transport- and Metabolism Genes in the Compartmentalized Anammox Bacterium Kuenenia stuttgartiensis. Front Microbiol 2020; 11:1959. [PMID: 32903544 PMCID: PMC7438415 DOI: 10.3389/fmicb.2020.01959] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/24/2020] [Indexed: 12/11/2022] Open
Abstract
Anaerobic ammonium-oxidizing (anammox) bacteria, members of the "Candidatus Brocadiaceae" family, play an important role in the nitrogen cycle and are estimated to be responsible for about half of the oceanic nitrogen loss to the atmosphere. Anammox bacteria combine ammonium with nitrite and produce dinitrogen gas via the intermediates nitric oxide and hydrazine (anammox reaction) while nitrate is formed as a by-product. These reactions take place in a specialized, membrane-enclosed compartment called the anammoxosome. Therefore, the substrates ammonium, nitrite and product nitrate have to cross the outer-, cytoplasmic-, and anammoxosome membranes to enter or exit the anammoxosome. The genomes of all anammox species harbor multiple copies of ammonium-, nitrite-, and nitrate transporter genes. Here we investigated how the distinct genes for ammonium-, nitrite-, and nitrate- transport were expressed during substrate limitation in membrane bioreactors. Transcriptome analysis of Kuenenia stuttgartiensis planktonic cells showed that four of the seven ammonium transporter homologs and two of the nine nitrite transporter homologs were significantly upregulated during ammonium-limited growth, while another ammonium transporter- and four nitrite transporter homologs were upregulated in nitrite limited growth conditions. The two nitrate transporters were expressed to similar levels in both conditions. In addition, genes encoding enzymes involved in the anammox reaction were differentially expressed, with those using nitrite as a substrate being upregulated under nitrite limited growth and those using ammonium as a substrate being upregulated during ammonium limitation. Taken together, these results give a first insight in the potential role of the multiple nutrient transporters in regulating transport of substrates and products in and out of the compartmentalized anammox cell.
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Affiliation(s)
| | | | | | | | | | | | | | - Laura van Niftrik
- Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University Nijmegen, Nijmegen, Netherlands
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Williamson G, Tamburrino G, Bizior A, Boeckstaens M, Dias Mirandela G, Bage MG, Pisliakov A, Ives CM, Terras E, Hoskisson PA, Marini AM, Zachariae U, Javelle A. A two-lane mechanism for selective biological ammonium transport. eLife 2020; 9:57183. [PMID: 32662768 PMCID: PMC7447429 DOI: 10.7554/elife.57183] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 07/13/2020] [Indexed: 11/13/2022] Open
Abstract
The transport of charged molecules across biological membranes faces the dual problem of accommodating charges in a highly hydrophobic environment while maintaining selective substrate translocation. This has been the subject of a particular controversy for the exchange of ammonium across cellular membranes, an essential process in all domains of life. Ammonium transport is mediated by the ubiquitous Amt/Mep/Rh transporters that includes the human Rhesus factors. Here, using a combination of electrophysiology, yeast functional complementation and extended molecular dynamics simulations, we reveal a unique two-lane pathway for electrogenic NH4+ transport in two archetypal members of the family, the transporters AmtB from Escherichia coli and Rh50 from Nitrosomonas europaea. The pathway underpins a mechanism by which charged H+ and neutral NH3 are carried separately across the membrane after NH4+ deprotonation. This mechanism defines a new principle of achieving transport selectivity against competing ions in a biological transport process.
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Affiliation(s)
- Gordon Williamson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Giulia Tamburrino
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Adriana Bizior
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Mélanie Boeckstaens
- Biology of Membrane Transport Laboratory, Department of Molecular Biology, Université Libre de Bruxelles, Gosselies, Belgium
| | - Gaëtan Dias Mirandela
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Marcus G Bage
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Andrei Pisliakov
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Callum M Ives
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Eilidh Terras
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Paul A Hoskisson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Anna Maria Marini
- Biology of Membrane Transport Laboratory, Department of Molecular Biology, Université Libre de Bruxelles, Gosselies, Belgium
| | - Ulrich Zachariae
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Arnaud Javelle
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
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25
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Tresguerres M, Clifford AM, Harter TS, Roa JN, Thies AB, Yee DP, Brauner CJ. Evolutionary links between intra- and extracellular acid-base regulation in fish and other aquatic animals. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2020; 333:449-465. [PMID: 32458594 DOI: 10.1002/jez.2367] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 03/10/2020] [Accepted: 05/06/2020] [Indexed: 12/17/2022]
Abstract
The acid-base relevant molecules carbon dioxide (CO2 ), protons (H+ ), and bicarbonate (HCO3 - ) are substrates and end products of some of the most essential physiological functions including aerobic and anaerobic respiration, ATP hydrolysis, photosynthesis, and calcification. The structure and function of many enzymes and other macromolecules are highly sensitive to changes in pH, and thus maintaining acid-base homeostasis in the face of metabolic and environmental disturbances is essential for proper cellular function. On the other hand, CO2 , H+ , and HCO3 - have regulatory effects on various proteins and processes, both directly through allosteric modulation and indirectly through signal transduction pathways. Life in aquatic environments presents organisms with distinct acid-base challenges that are not found in terrestrial environments. These include a relatively high CO2 relative to O2 solubility that prevents internal CO2 /HCO3 - accumulation to buffer pH, a lower O2 content that may favor anaerobic metabolism, and variable environmental CO2 , pH and O2 levels that require dynamic adjustments in acid-base homeostatic mechanisms. Additionally, some aquatic animals purposely create acidic or alkaline microenvironments that drive specialized physiological functions. For example, acidifying mechanisms can enhance O2 delivery by red blood cells, lead to ammonia trapping for excretion or buoyancy purposes, or lead to CO2 accumulation to promote photosynthesis by endosymbiotic algae. On the other hand, alkalinizing mechanisms can serve to promote calcium carbonate skeletal formation. This nonexhaustive review summarizes some of the distinct acid-base homeostatic mechanisms that have evolved in aquatic organisms to meet the particular challenges of this environment.
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Affiliation(s)
- Martin Tresguerres
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, California
| | - Alexander M Clifford
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, California
| | - Till S Harter
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, California
| | - Jinae N Roa
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, California
| | - Angus B Thies
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, California
| | - Daniel P Yee
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, California
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, Vancouver, Canada
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26
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Brito AS, Neuhäuser B, Wintjens R, Marini AM, Boeckstaens M. Yeast filamentation signaling is connected to a specific substrate translocation mechanism of the Mep2 transceptor. PLoS Genet 2020; 16:e1008634. [PMID: 32069286 PMCID: PMC7048316 DOI: 10.1371/journal.pgen.1008634] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 02/28/2020] [Accepted: 01/28/2020] [Indexed: 11/18/2022] Open
Abstract
The dimorphic transition from the yeast to the filamentous form of growth allows cells to explore their environment for more suitable niches and is often crucial for the virulence of pathogenic fungi. In contrast to their Mep1/3 paralogues, fungal Mep2-type ammonium transport proteins of the conserved Mep-Amt-Rh family have been assigned an additional receptor role required to trigger the filamentation signal in response to ammonium scarcity. Here, genetic, kinetic and structure-function analyses were used to shed light on the poorly characterized signaling role of Saccharomyces cerevisiae Mep2. We show that Mep2 variants lacking the C-terminal tail conserve the ability to induce filamentation, revealing that signaling can proceed in the absence of exclusive binding of a putative partner to the largest cytosolic domain of the protein. Our data support that filamentation signaling requires the conformational changes accompanying substrate translocation through the pore crossing the hydrophobic core of Mep2. pHluorin reporter assays show that the transport activity of Mep2 and of non-signaling Mep1 differently affect yeast cytosolic pH in vivo, and that the unique pore variant Mep2H194E, with apparent uncoupling of transport and signaling functions, acquires increased ability of acidification. Functional characterization in Xenopus oocytes reveals that Mep2 mediates electroneutral substrate translocation while Mep1 performs electrogenic transport. Our findings highlight that the Mep2-dependent filamentation induction is connected to its specific transport mechanism, suggesting a role of pH in signal mediation. Finally, we show that the signaling process is conserved for the Mep2 protein from the human pathogen Candida albicans. Fungal Mep2-type ammonium transport proteins of the conserved Mep-Amt-Rh family that includes human Rhesus factors are specifically required to allow filamentation in response to ammonium limitation. These proteins were therefore assigned a receptor role while the underlying mechanism of signal transduction remains poorly understood. The “transceptor” property has subsequently been proposed to concern transporters of all kind of micro- and macro- nutrients in eukaryotes, from fungi to human. However, bringing the firm demonstration of their existence remains challenging as variants with full uncoupling of transport and receptor functions are difficult to obtain. Our data question the involvement of the C-terminal extremity of Saccharomyces cerevisiae Mep2 in the signal mediation leading to filamentation. If signaling partners exist, they should also bind to cytosolic loops and/or membrane-embedded domains. The capacity of Mep2 to enable filamentation is closely intertwined to the mechanism of substrate translocation through the pore of the hydrophobic core of the protein. In Xenopus oocytes, the transport activity of non-signaling Mep1 is electrogenic while it is electroneutral for Mep2, the latter likely translocating the weak base NH3, but not the proton released after NH4+ recognition and depronotation. We propose that given consequences of a Mep2-specific transport process, such as an intracellular pH modification, could be the underlying cause of the filamentation signal ensured by Mep2-type proteins.
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Affiliation(s)
- Ana Sofia Brito
- Biology of Membrane Transport Laboratory, Molecular Biology Department, Université Libre de Bruxelles, Gosselies, Belgium
| | - Benjamin Neuhäuser
- Institute of Crop Science, Nutritional Crop Physiology, University of Hohenheim, Stuttgart, Germany
| | - René Wintjens
- Unité Microbiologie, Chimie Bioorganique et Macromoléculaire, Département RD3, Faculté de Pharmacie, Université Libre de Bruxelles, Brussels, Belgium
| | - Anna Maria Marini
- Biology of Membrane Transport Laboratory, Molecular Biology Department, Université Libre de Bruxelles, Gosselies, Belgium
- * E-mail: (AMM); (MB)
| | - Mélanie Boeckstaens
- Biology of Membrane Transport Laboratory, Molecular Biology Department, Université Libre de Bruxelles, Gosselies, Belgium
- * E-mail: (AMM); (MB)
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27
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Abstract
Here, we present a protocol for the functional characterization of the H+-coupled human peptide transporter PepT1 and sufficient notes to transfer the protocol to the Na+-coupled sugar transporter SGLT1, the organic cation transporter OCT2, the Na+/Ca2+ exchanger NCX, and the neuronal glutamate transporter EAAT3.The assay was developed for the commercially available SURFE2R N1 instrument (Nanion Technologies GmbH) which applies solid supported membrane (SSM)-based electrophysiology. This technique is widely used for the functional characterization of membrane transporters with more than 100 different transporters characterized so far. The technique is cost-effective, easy to use, and capable of high-throughput measurements.SSM-based electrophysiology utilizes SSM-coated gold sensors to physically adsorb membrane vesicles containing the protein of interest. A fast solution exchange provides the substrate and activates transport. For the measurement of PepT1 activity, we applied a peptide concentration jump to activate H+/peptide symport. Proton influx charges the sensor. A capacitive current is measured reflecting the transport activity of PepT1 . Multiple measurements on the same sensor allow for comparison of transport activity under different conditions. Here, we determine EC50 for PepT1-mediated glycylglycine transport and perform an inhibition experiment using the specific peptide inhibitor Lys[Z(NO2)]-Val.
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28
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Affiliation(s)
- Bert van den Berg
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Siobhan Lister
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Julian C. Rutherford
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
- * E-mail:
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29
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Molecular mechanisms associated with acidification and alkalization along the larval midgut of Musca domestica. Comp Biochem Physiol A Mol Integr Physiol 2019; 237:110535. [DOI: 10.1016/j.cbpa.2019.110535] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/01/2019] [Accepted: 08/01/2019] [Indexed: 01/07/2023]
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30
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Dondapati SK, Lübberding H, Zemella A, Thoring L, Wüstenhagen DA, Kubick S. Functional Reconstitution of Membrane Proteins Derived From Eukaryotic Cell-Free Systems. Front Pharmacol 2019; 10:917. [PMID: 31543813 PMCID: PMC6728924 DOI: 10.3389/fphar.2019.00917] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/22/2019] [Indexed: 11/23/2022] Open
Abstract
Cell-free protein synthesis (CFPS) based on eukaryotic Sf21 lysate is gaining interest among researchers due to its ability to handle the synthesis of complex human membrane proteins (MPs). Additionally Sf21 cell-free systems contain endogenous microsomal vesicles originally derived from the endoplasmic reticulum (ER). After CFPS, MPs will be translocated into the microsomal vesicles membranes present in the lysates. Thus microsomal membranes offer a natural environment for de novo synthesized MPs. Despite the advantage of synthesizing complex MPs with post translational modifications directly into the microsomal membranes without any additional solubilization supplements, batch based Sf21 cell-free synthesis suffers from low yields. The bottleneck for MPs in particular after the synthesis and incorporation into the microsomal membranes is to analyze their functionality. Apart from low yields of the synthesized MPs with batch based cell-free synthesis, the challenges arise in the form of cytoskeleton elements and peripheral endogenous proteins surrounding the microsomes which may impede the functional analysis of the synthesized proteins. So careful sample processing after the synthesis is particularly important for developing the appropriate functional assays. Here we demonstrate how MPs (native and batch synthesized) from ER derived microsomes can be processed for functional analysis by electrophysiology and radioactive uptake assay methods. Treatment of the microsomal membranes either with a sucrose washing step in the case of human serotonin transporter (hSERT) and sarco/endoplasmic reticulum Ca2+/ATPase (SERCA) pump or with mild detergents followed by the preparation of proteoliposomes in the case of the human voltage dependent anionic channel (hVDAC1) helps to analyze the functional properties of MPs.
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Affiliation(s)
- Srujan Kumar Dondapati
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg, Potsdam, Germany
| | - Henning Lübberding
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg, Potsdam, Germany
| | - Anne Zemella
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg, Potsdam, Germany
| | - Lena Thoring
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg, Potsdam, Germany
| | - Doreen A Wüstenhagen
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg, Potsdam, Germany
| | - Stefan Kubick
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg, Potsdam, Germany.,Faculty of Health Sciences, Joint Faculty of the Brandenburg University of Technology Cottbus - Senftenberg, The Brandenburg Medical School Theodor Fontane, University of Potsdam, Potsdam, Germany
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31
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Manipulating nitrogen regulation in diazotrophic bacteria for agronomic benefit. Biochem Soc Trans 2019; 47:603-614. [PMID: 30936245 PMCID: PMC6490700 DOI: 10.1042/bst20180342] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 03/05/2019] [Accepted: 03/06/2019] [Indexed: 11/29/2022]
Abstract
Biological nitrogen fixation (BNF) is controlled by intricate regulatory mechanisms to ensure that fixed nitrogen is readily assimilated into biomass and not released to the environment. Understanding the complex regulatory circuits that couple nitrogen fixation to ammonium assimilation is a prerequisite for engineering diazotrophic strains that can potentially supply fixed nitrogen to non-legume crops. In this review, we explore how the current knowledge of nitrogen metabolism and BNF regulation may allow strategies for genetic manipulation of diazotrophs for ammonia excretion and provide a contribution towards solving the nitrogen crisis.
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32
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Herrero A, Flores E. Genetic responses to carbon and nitrogen availability in Anabaena. Environ Microbiol 2018; 21:1-17. [PMID: 30066380 DOI: 10.1111/1462-2920.14370] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 07/27/2018] [Accepted: 07/29/2018] [Indexed: 11/27/2022]
Abstract
Heterocyst-forming cyanobacteria are filamentous organisms that perform oxygenic photosynthesis and CO2 fixation in vegetative cells and nitrogen fixation in heterocysts, which are formed under deprivation of combined nitrogen. These organisms can acclimate to use different sources of nitrogen and respond to different levels of CO2 . Following work mainly done with the best studied heterocyst-forming cyanobacterium, Anabaena, here we summarize the mechanisms of assimilation of ammonium, nitrate, urea and N2 , the latter involving heterocyst differentiation, and describe aspects of CO2 assimilation that involves a carbon concentration mechanism. These processes are subjected to regulation establishing a hierarchy in the assimilation of nitrogen sources -with preference for the most reduced nitrogen forms- and a dependence on sufficient carbon. This regulation largely takes place at the level of gene expression and is exerted by a variety of transcription factors, including global and pathway-specific transcriptional regulators. NtcA is a CRP-family protein that adjusts global gene expression in response to the C-to-N balance in the cells, and PacR is a LysR-family transcriptional regulator (LTTR) that extensively acclimates the cells to oxygenic phototrophy. A cyanobacterial-specific transcription factor, HetR, is involved in heterocyst differentiation, and other LTTR factors are specifically involved in nitrate and CO2 assimilation.
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Affiliation(s)
- Antonia Herrero
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, Américo Vespucio 49, E-41092, Seville, Spain
| | - Enrique Flores
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, Américo Vespucio 49, E-41092, Seville, Spain
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33
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Rein S, Lewe P, Andrade SL, Kacprzak S, Weber S. Global analysis of complex PELDOR time traces. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 295:17-26. [PMID: 30092553 DOI: 10.1016/j.jmr.2018.07.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 07/20/2018] [Accepted: 07/21/2018] [Indexed: 05/24/2023]
Abstract
Pulsed electron-electron double resonance (PELDOR, alternatively called DEER for double electron-electron resonance) pulse sequences allow for the detection of echo decay curves that are modulated by dipole-dipole-coupling frequencies of interacting electron spins. With increasing distance between them, the echo decay needs to be monitored over a progressively extended time period. However, since the echo intensity typically falls off exponentially with increasing time, this might be problematic with respect to the minimum signal-to-noise ratio required for a sound data analysis. In this contribution we present the new PELDOR analysis tool GloPel (Global analysis of PELDOR data), an open-source Python-based application, that allows to extract improved-quality distance distributions from PELDOR data for which no ideal signal-to-noise ratio can be achieved for a very long observation window. By using Tikhonov regularization, GloPel allows for the simultaneous analysis of two time traces acquired for a sample in two different observation time windows, thus taking advantage of both, the typically high signal-to-noise ratio of the time trace acquired at early times of the echo decay, and the best possible background function fitted for the decay at later times, which is in most cases superimposed with considerable noise. In this way, short distances are not overseen in the higher noise of the longer time traces while long distances are not artificially shortened by limiting the observation time window of the experiment. Following our suggested data acquisition procedure, a significant reduction of the measurement time may also be achieved.
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Affiliation(s)
- Stephan Rein
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Philipp Lewe
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Susana L Andrade
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universität Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany
| | - Sylwia Kacprzak
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
| | - Stefan Weber
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
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34
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Mirandela GD, Tamburrino G, Hoskisson PA, Zachariae U, Javelle A. The lipid environment determines the activity of the Escherichia coli ammonium transporter AmtB. FASEB J 2018; 33:1989-1999. [PMID: 30211659 PMCID: PMC6338640 DOI: 10.1096/fj.201800782r] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The movement of ammonium across biologic membranes is a fundamental process in all living organisms and is mediated by the ubiquitous ammonium transporter/methylammonium permease/rhesus protein (Amt/Mep/Rh) family of transporters. Recent structural analysis and coupled mass spectrometry studies have shown that the Escherichia coli ammonium transporter AmtB specifically binds 1-palmitoyl-2-oleoyl phosphatidylglycerol (POPG). Upon POPG binding, several residues of AmtB undergo a small conformational change, which stabilizes the protein against unfolding. However, no studies have so far been conducted, to our knowledge, to explore whether POPG binding to AmtB has functional consequences. Here, we used an in vitro experimental assay with purified components, together with molecular dynamics simulations, to characterize the relation between POPG binding and AmtB activity. We show that the AmtB activity is electrogenic. Our results indicate that the activity, at the molecular level, of Amt in archaebacteria and eubacteria may differ. We also show that POPG is an important cofactor for AmtB activity and that, in the absence of POPG, AmtB cannot complete the full translocation cycle. Furthermore, our simulations reveal previously undiscovered POPG binding sites on the intracellular side of the lipid bilayer between the AmtB subunits. Possible molecular mechanisms explaining the functional role of POPG are discussed.-Mirandela, G. D., Tamburrino, G., Hoskisson, P. A., Zachariae, U., Javelle, A. The lipid environment determines the activity of the Escherichia coli ammonium transporter AmtB.
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Affiliation(s)
- Gaëtan Dias Mirandela
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Giulia Tamburrino
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Paul A Hoskisson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Ulrich Zachariae
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Physics, School of Science and Engineering, University of Dundee, Dundee, United Kingdom
| | - Arnaud Javelle
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
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35
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Comparative transcriptomic and proteomic analysis of Arthrobacter sp. CGMCC 3584 responding to dissolved oxygen for cAMP production. Sci Rep 2018; 8:1246. [PMID: 29352122 PMCID: PMC5775200 DOI: 10.1038/s41598-017-18889-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 12/18/2017] [Indexed: 01/09/2023] Open
Abstract
Arthrobacter sp. CGMCC 3584 is able to produce high yields of extracellular cyclic adenosine monophosphate (cAMP), which plays a vital role in the field of treatment of disease and animal food, during aerobic fermentation. However, the molecular basis of cAMP production in Arthrobacter species is rarely explored. Here, for the first time, we report the comparative transcriptomic and proteomic study of Arthrobacter cells to elucidate the higher productivity of cAMP under high oxygen supply. We finally obtained 14.1% and 19.3% of the Arthrobacter genome genes which were up-regulated and down-regulated notably, respectively, with high oxygen supply, and identified 54 differently expressed proteins. Our results revealed that high oxygen supply had two major effects on metabolism: inhibition of glycolysis, pyruvate metabolism, nitrogen metabolism, and amino acid metabolism (histidine, branched-chain amino acids and glutamate metabolism); enhancement of the tricarboxylic acid cycle and purine metabolism. We also found that regulation of adenylate cyclase and phosphodiesterase was not significant under high oxygen supply, suggesting efficient cAMP export might be important in cAMP production. These findings may contribute to further understanding of capacities of Arthrobacter species and would be highly useful in genetic regulation for desirable production.
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36
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Pflüger T, Hernández CF, Lewe P, Frank F, Mertens H, Svergun D, Baumstark MW, Lunin VY, Jetten MSM, Andrade SLA. Signaling ammonium across membranes through an ammonium sensor histidine kinase. Nat Commun 2018; 9:164. [PMID: 29323112 PMCID: PMC5764959 DOI: 10.1038/s41467-017-02637-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 12/15/2017] [Indexed: 01/07/2023] Open
Abstract
Sensing and uptake of external ammonium is essential for anaerobic ammonium-oxidizing (anammox) bacteria, and is typically the domain of the ubiquitous Amt/Rh ammonium transporters. Here, we report on the structure and function of an ammonium sensor/transducer from the anammox bacterium "Candidatus Kuenenia stuttgartiensis" that combines a membrane-integral ammonium transporter domain with a fused histidine kinase. It contains a high-affinity ammonium binding site not present in assimilatory Amt proteins. The levels of phosphorylated histidine in the kinase are coupled to the presence of ammonium, as conformational changes during signal recognition by the Amt module are transduced internally to modulate the kinase activity. The structural analysis of this ammonium sensor by X-ray crystallography and small-angle X-ray-scattering reveals a flexible, bipartite system that recruits a large uptake transporter as a sensory module and modulates its functionality to achieve a mechanistic coupling to a kinase domain in order to trigger downstream signaling events.
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Affiliation(s)
- Tobias Pflüger
- Institute for Biochemistry, University of Freiburg, Albertstr. 21, Freiburg, 79104, Germany
| | - Camila F Hernández
- Institute for Biochemistry, University of Freiburg, Albertstr. 21, Freiburg, 79104, Germany
| | - Philipp Lewe
- Institute for Biochemistry, University of Freiburg, Albertstr. 21, Freiburg, 79104, Germany
| | - Fabian Frank
- Institute for Biochemistry, University of Freiburg, Albertstr. 21, Freiburg, 79104, Germany
| | - Haydyn Mertens
- European Molecular Biology Laboratory, Hamburg Unit, EMBL c/o DESY, Notkestr. 85, Hamburg, D-22603, Germany
| | - Dmitri Svergun
- European Molecular Biology Laboratory, Hamburg Unit, EMBL c/o DESY, Notkestr. 85, Hamburg, D-22603, Germany
| | - Manfred W Baumstark
- Center for Medicine, Institute for Exercise and Occupational Medicine, Medical Center, University of Freiburg, Hugstetterstr. 55, Freiburg, 79106, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, 79106, Germany
| | - Vladimir Y Lunin
- Institute of Mathematical Problems of Biology RAS, Keldysh Institute of Applied Mathematics of Russian Academy of Sciences, Vitkevicha str. 1, Pushchino, 142290, Russia
| | - Mike S M Jetten
- Department of Microbiology, Radboud University, Institute for Water and Wetland Research, Heyendaalseweg 135, Nijmegen, NL-6525 AJ, The Netherlands
| | - Susana L A Andrade
- Institute for Biochemistry, University of Freiburg, Albertstr. 21, Freiburg, 79104, Germany. .,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestr. 1, Freiburg, 79104, Germany.
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37
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Abstract
Functional characterization of transport proteins using conventional electrophysiology can be challenging, especially for low turnover transporters or transporters from bacteria and intracellular compartments. Solid-supported membrane (SSM)-based electrophysiology is a sensitive and cell-free assay technique for the characterization of electrogenic membrane proteins. Purified proteins reconstituted into proteoliposomes or membrane vesicles from cell culture or native tissues are adsorbed to the sensor holding an SSM. A substrate or a ligand is applied via rapid solution exchange. The electrogenic transporter activity charges the sensor, which is recorded as a transient current. The high stability of the SSM allows cumulative measurements on the same sensor using different experimental conditions. This allows the determination of kinetic properties including EC50, IC50, Km, KD, and rate constants of electrogenic reactions. About 100 different transporters have been measured so far using this technique, among them symporters, exchangers, uniporters, ATP-, redox-, and light-driven ion pumps, as well as receptors and ion channels. Different instruments apply this technique: the laboratory setups use a closed flow-through arrangement, while the commercially available SURFE2R N1 resembles a pipetting robot. For drug screening purposes high-throughput systems, such as the SURFE2R 96SE enable the simultaneous measurement of up to 96 sensors.
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Affiliation(s)
- Andre Bazzone
- Max Planck Institute of Biophysics, Frankfurt/Main, Germany; Nanion Technologies GmbH, Munich, Germany
| | | | - Klaus Fendler
- Max Planck Institute of Biophysics, Frankfurt/Main, Germany.
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38
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van den Berg B, Chembath A, Jefferies D, Basle A, Khalid S, Rutherford JC. Structural basis for Mep2 ammonium transceptor activation by phosphorylation. Nat Commun 2016; 7:11337. [PMID: 27088325 PMCID: PMC4852598 DOI: 10.1038/ncomms11337] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 03/14/2016] [Indexed: 11/18/2022] Open
Abstract
Mep2 proteins are fungal transceptors that play an important role as ammonium sensors in fungal development. Mep2 activity is tightly regulated by phosphorylation, but how this is achieved at the molecular level is not clear. Here we report X-ray crystal structures of the Mep2 orthologues from Saccharomyces cerevisiae and Candida albicans and show that under nitrogen-sufficient conditions the transporters are not phosphorylated and present in closed, inactive conformations. Relative to the open bacterial ammonium transporters, non-phosphorylated Mep2 exhibits shifts in cytoplasmic loops and the C-terminal region (CTR) to occlude the cytoplasmic exit of the channel and to interact with His2 of the twin-His motif. The phosphorylation site in the CTR is solvent accessible and located in a negatively charged pocket ∼30 Å away from the channel exit. The crystal structure of phosphorylation-mimicking Mep2 variants from C. albicans show large conformational changes in a conserved and functionally important region of the CTR. The results allow us to propose a model for regulation of eukaryotic ammonium transport by phosphorylation.
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Affiliation(s)
- Bert van den Berg
- Institute for Cell and Molecular Biosciences, The Medical
School, Newcastle University, Newcastle upon Tyne
NE2 4HH, UK
| | - Anupama Chembath
- Institute for Cell and Molecular Biosciences, The Medical
School, Newcastle University, Newcastle upon Tyne
NE2 4HH, UK
| | - Damien Jefferies
- School of Chemistry, University of Southampton,
Highfield Campus, Southampton
SO17 1BJ, UK
| | - Arnaud Basle
- Institute for Cell and Molecular Biosciences, The Medical
School, Newcastle University, Newcastle upon Tyne
NE2 4HH, UK
| | - Syma Khalid
- School of Chemistry, University of Southampton,
Highfield Campus, Southampton
SO17 1BJ, UK
| | - Julian C. Rutherford
- Institute for Cell and Molecular Biosciences, The Medical
School, Newcastle University, Newcastle upon Tyne
NE2 4HH, UK
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39
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Availability of Amino Acids Extends Chronological Lifespan by Suppressing Hyper-Acidification of the Environment in Saccharomyces cerevisiae. PLoS One 2016; 11:e0151894. [PMID: 26991662 PMCID: PMC4798762 DOI: 10.1371/journal.pone.0151894] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 03/04/2016] [Indexed: 11/24/2022] Open
Abstract
The chronological lifespan of Saccharomyces cerevisiae represents the duration of cell survival in the postdiauxic and stationary phases. Using a prototrophic strain derived from the standard auxotrophic laboratory strain BY4742, we showed that supplementation of non-essential amino acids to a synthetic defined (SD) medium increases maximal cell growth and extends the chronological lifespan. The positive effects of amino acids can be reproduced by modulating the medium pH, indicating that amino acids contribute to chronological longevity in a cell-extrinsic manner by alleviating medium acidification. In addition, we showed that the amino acid-mediated effects on extension of chronological longevity are independent of those achieved through a reduction in the TORC1 pathway, which is mediated in a cell-intrinsic manner. Since previous studies showed that extracellular acidification causes mitochondrial dysfunction and leads to cell death, our results provide a path to premature chronological aging caused by differences in available nitrogen sources. Moreover, acidification of culture medium is generally associated with culture duration and cell density; thus, further studies are required on cell physiology of auxotrophic yeast strains during the stationary phase because an insufficient supply of essential amino acids may cause alterations in environmental conditions.
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40
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Nagarajan Y, Rongala J, Luang S, Singh A, Shadiac N, Hayes J, Sutton T, Gilliham M, Tyerman SD, McPhee G, Voelcker NH, Mertens HDT, Kirby NM, Lee JG, Yingling YG, Hrmova M. A Barley Efflux Transporter Operates in a Na+-Dependent Manner, as Revealed by a Multidisciplinary Platform. THE PLANT CELL 2016; 28:202-18. [PMID: 26672067 PMCID: PMC4746678 DOI: 10.1105/tpc.15.00625] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 12/11/2015] [Indexed: 05/02/2023]
Abstract
Plant growth and survival depend upon the activity of membrane transporters that control the movement and distribution of solutes into, around, and out of plants. Although many plant transporters are known, their intrinsic properties make them difficult to study. In barley (Hordeum vulgare), the root anion-permeable transporter Bot1 plays a key role in tolerance to high soil boron, facilitating the efflux of borate from cells. However, its three-dimensional structure is unavailable and the molecular basis of its permeation function is unknown. Using an integrative platform of computational, biophysical, and biochemical tools as well as molecular biology, electrophysiology, and bioinformatics, we provide insight into the origin of transport function of Bot1. An atomistic model, supported by atomic force microscopy measurements, reveals that the protein folds into 13 transmembrane-spanning and five cytoplasmic α-helices. We predict a trimeric assembly of Bot1 and the presence of a Na(+) ion binding site, located in the proximity of a pore that conducts anions. Patch-clamp electrophysiology of Bot1 detects Na(+)-dependent polyvalent anion transport in a Nernstian manner with channel-like characteristics. Using alanine scanning, molecular dynamics simulations, and transport measurements, we show that conductance by Bot1 is abolished by removal of the Na(+) ion binding site. Our data enhance the understanding of the permeation functions of Bot1.
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Affiliation(s)
- Yagnesh Nagarajan
- Australian Centre for Plant Functional Genomics, School of Agriculture, Food, and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia
| | - Jay Rongala
- Australian Centre for Plant Functional Genomics, School of Agriculture, Food, and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia
| | - Sukanya Luang
- Australian Centre for Plant Functional Genomics, School of Agriculture, Food, and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia
| | - Abhishek Singh
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7907
| | - Nadim Shadiac
- Australian Centre for Plant Functional Genomics, School of Agriculture, Food, and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia
| | - Julie Hayes
- Australian Centre for Plant Functional Genomics, School of Agriculture, Food, and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia
| | - Tim Sutton
- Australian Centre for Plant Functional Genomics, School of Agriculture, Food, and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia
| | - Matthew Gilliham
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Agriculture, Food, and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia
| | - Stephen D Tyerman
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Agriculture, Food, and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia
| | - Gordon McPhee
- Mawson Institute, University of South Australia, Mawson Lakes, South Australia 5095, Australia
| | - Nicolas H Voelcker
- Mawson Institute, University of South Australia, Mawson Lakes, South Australia 5095, Australia
| | - Haydyn D T Mertens
- Small- and Wide-Angle X-Ray Scattering Beamline, Australian Synchrotron, Clayton, Victoria 3168, Australia
| | - Nigel M Kirby
- Small- and Wide-Angle X-Ray Scattering Beamline, Australian Synchrotron, Clayton, Victoria 3168, Australia
| | - Jung-Goo Lee
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7907
| | - Yaroslava G Yingling
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7907
| | - Maria Hrmova
- Australian Centre for Plant Functional Genomics, School of Agriculture, Food, and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia
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41
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Neuhäuser B, Dynowski M, Ludewig U. Switching substrate specificity of AMT/MEP/ Rh proteins. Channels (Austin) 2015; 8:496-502. [PMID: 25483282 DOI: 10.4161/19336950.2014.967618] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In organisms from all kingdoms of life, ammonia and its conjugated ion ammonium are transported across membranes by proteins of the AMT/Rh family. Efficient and successful growth often depends on sufficient ammonium nutrition. The proteins mediating this transport, the so called Ammonium Transporter (AMT) or Rhesus like (Rh) proteins, share a very similar trimeric overall structure and a high sequence similarity even throughout the kingdoms. Even though structural components of the transport mechanism, like an external substrate recruitment site, an essential twin histidine pore motif, a phenylalanine gate and the hydrophobic pore are strongly conserved and have been analyzed in detail by molecular dynamic simulations and mutational studies, the substrate(s), which pass the central pores of the AMT/Rh subunits, NH4(+), NH3 + H(+), NH4(+) + H(+) or NH3, are still a matter of debate for most proteins, including the best characterized AmtB protein from Escherichia coli. The lack of a robust expression system for functional analysis has hampered proof of structural and mutational studies, although the NH3 transport function for Rh-like proteins is rarely disputed. In plant transporters belonging to the subfamily AMT1, transport is associated with electrical currents, while some plant transporters, notably of the AMT2 type, were suggested to transport NH3 across the membrane, without associated ionic currents. Here we summarize data in favor of each substrate for the distinct AMT/Rh classes, discuss mutants and how they differ in structure and functionality. A common mechanism with deprotonation and subsequent NH3 transport through the central subunit pore is suggested.
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Affiliation(s)
- Benjamin Neuhäuser
- a Institute of Crop Science; Nutritional Crop Physiology ; University of Hohenheim ; Stuttgart , Germany
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42
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Mechanism of NH 4 + Recruitment and NH 3 Transport in Rh Proteins. Structure 2015; 23:1550-1557. [DOI: 10.1016/j.str.2015.06.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 05/27/2015] [Accepted: 06/08/2015] [Indexed: 01/19/2023]
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43
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44
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Structure of the V. cholerae Na+-pumping NADH:quinone oxidoreductase. Nature 2015; 516:62-7. [PMID: 25471880 DOI: 10.1038/nature14003] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 10/24/2014] [Indexed: 11/08/2022]
Abstract
NADH oxidation in the respiratory chain is coupled to ion translocation across the membrane to build up an electrochemical gradient. The sodium-translocating NADH:quinone oxidoreductase (Na(+)-NQR), a membrane protein complex widespread among pathogenic bacteria, consists of six subunits, NqrA, B, C, D, E and F. To our knowledge, no structural information on the Na(+)-NQR complex has been available until now. Here we present the crystal structure of the Na(+)-NQR complex at 3.5 Å resolution. The arrangement of cofactors both at the cytoplasmic and the periplasmic side of the complex, together with a hitherto unknown iron centre in the midst of the membrane-embedded part, reveals an electron transfer pathway from the NADH-oxidizing cytoplasmic NqrF subunit across the membrane to the periplasmic NqrC, and back to the quinone reduction site on NqrA located in the cytoplasm. A sodium channel was localized in subunit NqrB, which represents the largest membrane subunit of the Na(+)-NQR and is structurally related to urea and ammonia transporters. On the basis of the structure we propose a mechanism of redox-driven Na(+) translocation where the change in redox state of the flavin mononucleotide cofactor in NqrB triggers the transport of Na(+) through the observed channel.
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45
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Offre P, Kerou M, Spang A, Schleper C. Variability of the transporter gene complement in ammonia-oxidizing archaea. Trends Microbiol 2014; 22:665-75. [PMID: 25169021 DOI: 10.1016/j.tim.2014.07.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Revised: 07/17/2014] [Accepted: 07/30/2014] [Indexed: 12/19/2022]
Abstract
Ammonia-oxidizing archaea (AOA) are a widespread and abundant component of microbial communities in many different ecosystems. The extent of physiological differences between individual AOA is, however, unknown. Here, we compare the transporter gene complements of six AOA, from four different environments and two major clades, to assess their potential for substrate uptake and efflux. Each of the corresponding AOA genomes encode a unique set of transporters and although the composition of AOA transporter complements follows a phylogenetic pattern, few transporter families are conserved in all investigated genomes. A comparison of ammonia transporters encoded by archaeal and bacterial ammonia oxidizers highlights the variance among AOA lineages as well as their distinction from the ammonia-oxidizing bacteria, and suggests differential ecological adaptations.
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Affiliation(s)
- Pierre Offre
- University of Vienna, Department of Ecogenomics and Systems Biology, Archaea Biology and Ecogenomics Division, Althanstrasse 14, A-1090 Wien, Austria.
| | - Melina Kerou
- University of Vienna, Department of Ecogenomics and Systems Biology, Archaea Biology and Ecogenomics Division, Althanstrasse 14, A-1090 Wien, Austria
| | - Anja Spang
- Uppsala University, Department of Cell and Molecular Biology, Science for Life Laboratory, Box 596, SE-75123, Uppsala, Sweden
| | - Christa Schleper
- University of Vienna, Department of Ecogenomics and Systems Biology, Archaea Biology and Ecogenomics Division, Althanstrasse 14, A-1090 Wien, Austria.
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