1
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Papp E, Vattay G. Computation of biological conductance with Liouville quantum master equation. Sci Rep 2024; 14:19571. [PMID: 39174593 PMCID: PMC11341803 DOI: 10.1038/s41598-024-70348-z] [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: 03/13/2024] [Accepted: 08/14/2024] [Indexed: 08/24/2024] Open
Abstract
Recent experiments have revealed that single proteins can display high conductivity, which stays finite for low temperatures, decays slowly with distance, and exhibits a rich spatial structure featuring highly conducting and strongly insulating domains. Here, we intruduce a new formula by combining the density matrix of the Liouville-Master Equation simulating quantum transport in nanoscale devices, and the phenomenological model of electronic conductance through molecules, that can account for the observed distance- and temperature dependence of conductance in proteins. We demonstrate its efficacy on experimentally highly conductive extracellular cytochrome nanowires, which are good candidates to illustrate our new approach by calculating and visualizing their electronic wiring, given the interest in the arrangement of their conducting and insulating parts. As proteins and protein nanowires exhibit significant potential for diverse applications, including energy production and sensing, our computational technique can accelerate the design of nano-bioelectronic devices.
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Affiliation(s)
- Eszter Papp
- Department of Physics of Complex Systems, Eötvös Loránd University, Egyetem tér 1-3., Budapest, 1053, Hungary.
| | - Gábor Vattay
- Department of Physics of Complex Systems, Eötvös Loránd University, Egyetem tér 1-3., Budapest, 1053, Hungary
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2
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Hardy BJ, Dubiel P, Bungay EL, Rudin M, Williams C, Arthur CJ, Guberman‐Pfeffer MJ, Sofia Oliveira A, Curnow P, Anderson JLR. Delineating redox cooperativity in water-soluble and membrane multiheme cytochromes through protein design. Protein Sci 2024; 33:e5113. [PMID: 38980168 PMCID: PMC11232281 DOI: 10.1002/pro.5113] [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: 05/17/2024] [Revised: 06/26/2024] [Accepted: 06/27/2024] [Indexed: 07/10/2024]
Abstract
Nature has evolved diverse electron transport proteins and multiprotein assemblies essential to the generation and transduction of biological energy. However, substantially modifying or adapting these proteins for user-defined applications or to gain fundamental mechanistic insight can be hindered by their inherent complexity. De novo protein design offers an attractive route to stripping away this confounding complexity, enabling us to probe the fundamental workings of these bioenergetic proteins and systems, while providing robust, modular platforms for constructing completely artificial electron-conducting circuitry. Here, we use a set of de novo designed mono-heme and di-heme soluble and membrane proteins to delineate the contributions of electrostatic micro-environments and dielectric properties of the surrounding protein medium on the inter-heme redox cooperativity that we have previously reported. Experimentally, we find that the two heme sites in both the water-soluble and membrane constructs have broadly equivalent redox potentials in isolation, in agreement with Poisson-Boltzmann Continuum Electrostatics calculations. BioDC, a Python program for the estimation of electron transfer energetics and kinetics within multiheme cytochromes, also predicts equivalent heme sites, and reports that burial within the low dielectric environment of the membrane strengthens heme-heme electrostatic coupling. We conclude that redox cooperativity in our diheme cytochromes is largely driven by heme electrostatic coupling and confirm that this effect is greatly strengthened by burial in the membrane. These results demonstrate that while our de novo proteins present minimalist, new-to-nature constructs, they enable the dissection and microscopic examination of processes fundamental to the function of vital, yet complex, bioenergetic assemblies.
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Affiliation(s)
| | | | | | - May Rudin
- School of BiochemistryUniversity of BristolBristolUK
| | | | | | | | | | - Paul Curnow
- School of BiochemistryUniversity of BristolBristolUK
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3
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Bishara Robertson IL, Zhang H, Reisner E, Butt JN, Jeuken LJC. Engineering of bespoke photosensitiser-microbe interfaces for enhanced semi-artificial photosynthesis. Chem Sci 2024; 15:9893-9914. [PMID: 38966358 PMCID: PMC11220614 DOI: 10.1039/d4sc00864b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Accepted: 05/20/2024] [Indexed: 07/06/2024] Open
Abstract
Biohybrid systems for solar fuel production integrate artificial light-harvesting materials with biological catalysts such as microbes. In this perspective, we discuss the rational design of the abiotic-biotic interface in biohybrid systems by reviewing microbes and synthetic light-harvesting materials, as well as presenting various approaches to coupling these two components together. To maximise performance and scalability of such semi-artificial systems, we emphasise that the interfacial design requires consideration of two important aspects: attachment and electron transfer. It is our perspective that rational design of this photosensitiser-microbe interface is required for scalable solar fuel production. The design and assembly of a biohybrid with a well-defined electron transfer pathway allows mechanistic characterisation and optimisation for maximum efficiency. Introduction of additional catalysts to the system can close the redox cycle, omitting the need for sacrificial electron donors. Studies that electronically couple light-harvesters to well-defined biological entities, such as emerging photosensitiser-enzyme hybrids, provide valuable knowledge for the strategic design of whole-cell biohybrids. Exploring the interactions between light-harvesters and redox proteins can guide coupling strategies when translated into larger, more complex microbial systems.
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Affiliation(s)
| | - Huijie Zhang
- Leiden Institute of Chemistry, Leiden University PO Box 9502 Leiden 2300 RA the Netherlands
| | - Erwin Reisner
- Yusuf Hamied Department of Chemistry, University of Cambridge Cambridge CB2 1EW UK
| | - Julea N Butt
- School of Chemistry and School of Biological Sciences, University of East Anglia Norwich Research Park Norwich NR4 7TJ UK
| | - Lars J C Jeuken
- Leiden Institute of Chemistry, Leiden University PO Box 9502 Leiden 2300 RA the Netherlands
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4
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Schoelmerich MC, Ly L, West-Roberts J, Shi LD, Shen C, Malvankar NS, Taib N, Gribaldo S, Woodcroft BJ, Schadt CW, Al-Shayeb B, Dai X, Mozsary C, Hickey S, He C, Beaulaurier J, Juul S, Sachdeva R, Banfield JF. Borg extrachromosomal elements of methane-oxidizing archaea have conserved and expressed genetic repertoires. Nat Commun 2024; 15:5414. [PMID: 38926353 PMCID: PMC11208441 DOI: 10.1038/s41467-024-49548-8] [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: 04/11/2024] [Accepted: 06/10/2024] [Indexed: 06/28/2024] Open
Abstract
Borgs are huge extrachromosomal elements (ECE) of anaerobic methane-consuming "Candidatus Methanoperedens" archaea. Here, we used nanopore sequencing to validate published complete genomes curated from short reads and to reconstruct new genomes. 13 complete and four near-complete linear genomes share 40 genes that define a largely syntenous genome backbone. We use these conserved genes to identify new Borgs from peatland soil and to delineate Borg phylogeny, revealing two major clades. Remarkably, Borg genes encoding nanowire-like electron-transferring cytochromes and cell surface proteins are more highly expressed than those of host Methanoperedens, indicating that Borgs augment the Methanoperedens activity in situ. We reconstructed the first complete 4.00 Mbp genome for a Methanoperedens that is inferred to be a Borg host and predicted its methylation motifs, which differ from pervasive TC and CC methylation motifs of the Borgs. Thus, methylation may enable Methanoperedens to distinguish their genomes from those of Borgs. Very high Borg to Methanoperedens ratios and structural predictions suggest that Borgs may be capable of encapsulation. The findings clearly define Borgs as a distinct class of ECE with shared genomic signatures, establish their diversification from a common ancestor with genetic inheritance, and raise the possibility of periodic existence outside of host cells.
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Affiliation(s)
- Marie C Schoelmerich
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
- Department of Environmental Systems Sciences, ETH Zurich, 8092, Zurich, Switzerland
| | - Lynn Ly
- Oxford Nanopore Technologies Inc, New York, NY, USA
| | - Jacob West-Roberts
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, USA
| | - Ling-Dong Shi
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
| | - Cong Shen
- Microbial Sciences Institute, Yale University, New Haven, CT, USA
- Deptartment of Molecular Biophysics and Biochemistry, Yale University, West Haven, CT, USA
| | - Nikhil S Malvankar
- Microbial Sciences Institute, Yale University, New Haven, CT, USA
- Deptartment of Molecular Biophysics and Biochemistry, Yale University, West Haven, CT, USA
| | - Najwa Taib
- Institut Pasteur, Université de Paris cité, Unit Evolutionary Biology of the Microbial Cell, Paris, France
| | - Simonetta Gribaldo
- Institut Pasteur, Université de Paris cité, Unit Evolutionary Biology of the Microbial Cell, Paris, France
| | - Ben J Woodcroft
- Centre for Microbiome Research, School of Biomedical Sciences, Queensland University of Technology (QUT), Translational Research Institute, Woolloongabba, QLD, Australia
| | - Christopher W Schadt
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
- Department of Microbiology, University of Tennessee, Knoxville, TN, USA
| | - Basem Al-Shayeb
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
| | | | | | - Scott Hickey
- Oxford Nanopore Technologies Inc, New York, NY, USA
| | - Christine He
- Oxford Nanopore Technologies Inc, New York, NY, USA
| | | | - Sissel Juul
- Oxford Nanopore Technologies Inc, New York, NY, USA
| | - Rohan Sachdeva
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
| | - Jillian F Banfield
- Innovative Genomics Institute, University of California, Berkeley, CA, USA.
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, USA.
- Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.
- Department of Earth and Planetary Science, University of California, Berkeley, CA, USA.
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5
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Shi LD, West-Roberts J, Schoelmerich MC, Penev PI, Chen L, Amano Y, Lei S, Sachdeva R, Banfield JF. Methanotrophic Methanoperedens archaea host diverse and interacting extrachromosomal elements. Nat Microbiol 2024:10.1038/s41564-024-01740-8. [PMID: 38918468 DOI: 10.1038/s41564-024-01740-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 05/20/2024] [Indexed: 06/27/2024]
Abstract
Methane emissions are mitigated by anaerobic methane-oxidizing archaea, including Methanoperedens. Some Methanoperedens host huge extrachromosomal genetic elements (ECEs) called Borgs that may modulate their activity, yet the broader diversity of Methanoperedens ECEs is understudied. Here we report small enigmatic linear ECEs, circular viruses and unclassified ECEs that are predicted to replicate within Methanoperedens. Linear ECEs have inverted terminal repeats, tandem repeats and coding patterns that are strongly reminiscent of Borgs, but they are only 52-145 kb in length. As they share proteins with Borgs and Methanoperedens, we refer to them as mini-Borgs. Mini-Borgs are genetically diverse and can be assigned to at least five family-level groups. We identify eight families of Methanoperedens viruses, some of which encode multi-haem cytochromes, and circular ECEs encoding transposon-associated TnpB genes with proximal population-heterogeneous CRISPR arrays. These ECEs exchange genetic information with each other and with Methanoperedens, probably impacting their archaeal host activity and evolution.
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Affiliation(s)
- Ling-Dong Shi
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Jacob West-Roberts
- Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA, USA
| | - Marie C Schoelmerich
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA
- Department of Environmental Systems Sciences, ETH Zurich, Zurich, Switzerland
| | - Petar I Penev
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA
| | - LinXing Chen
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Yuki Amano
- Sector of Decommissioning and Radioactive Wastes Management, Japan Atomic Energy Agency, Ibaraki, Japan
| | - Shufei Lei
- Earth and Planetary Science, University of California, Berkeley, Berkeley, CA, USA
| | - Rohan Sachdeva
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Jillian F Banfield
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA.
- Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA, USA.
- Earth and Planetary Science, University of California, Berkeley, Berkeley, CA, USA.
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6
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Liu J, Eastep GN, Cvirkaite-Krupovic V, Rich-New ST, Kreutzberger MAB, Egelman EH, Krupovic M, Wang F. Two distinct archaeal type IV pili structures formed by proteins with identical sequence. Nat Commun 2024; 15:5049. [PMID: 38877064 PMCID: PMC11178852 DOI: 10.1038/s41467-024-45062-z] [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: 08/07/2023] [Accepted: 01/10/2024] [Indexed: 06/16/2024] Open
Abstract
Type IV pili (T4P) represent one of the most common varieties of surface appendages in archaea. These filaments, assembled from small pilin proteins, can be many microns long and serve diverse functions, including adhesion, biofilm formation, motility, and intercellular communication. Here, we determine atomic structures of two distinct adhesive T4P from Saccharolobus islandicus via cryo-electron microscopy (cryo-EM). Unexpectedly, both pili were assembled from the same pilin polypeptide but under different growth conditions. One filament, denoted mono-pilus, conforms to canonical archaeal T4P structures where all subunits are equivalent, whereas in the other filament, the tri-pilus, the same polypeptide exists in three different conformations. The three conformations in the tri-pilus are very different from the single conformation found in the mono-pilus, and involve different orientations of the outer immunoglobulin-like domains, mediated by a very flexible linker. Remarkably, the outer domains rotate nearly 180° between the mono- and tri-pilus conformations. Both forms of pili require the same ATPase and TadC-like membrane pore for assembly, indicating that the same secretion system can produce structurally very different filaments. Our results show that the structures of archaeal T4P appear to be less constrained and rigid than those of the homologous archaeal flagellar filaments that serve as helical propellers.
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Affiliation(s)
- Junfeng Liu
- Institut Pasteur, Université Paris Cité, Archaeal Virology Unit, Paris, France
| | - Gunnar N Eastep
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | - Shane T Rich-New
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Mark A B Kreutzberger
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA, USA.
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, Archaeal Virology Unit, Paris, France.
| | - Fengbin Wang
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, USA.
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA, USA.
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7
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Suzuki S, Ishii S, Chadwick GL, Tanaka Y, Kouzuma A, Watanabe K, Inagaki F, Albertsen M, Nielsen PH, Nealson KH. A non-methanogenic archaeon within the order Methanocellales. Nat Commun 2024; 15:4858. [PMID: 38871712 DOI: 10.1038/s41467-024-48185-5] [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: 08/01/2023] [Accepted: 04/22/2024] [Indexed: 06/15/2024] Open
Abstract
Serpentinization, a geochemical process found on modern and ancient Earth, provides an ultra-reducing environment that can support microbial methanogenesis and acetogenesis. Several groups of archaea, such as the order Methanocellales, are characterized by their ability to produce methane. Here, we generate metagenomic sequences from serpentinized springs in The Cedars, California, and construct a circularized metagenome-assembled genome of a Methanocellales archaeon, termed Met12, that lacks essential methanogenesis genes. The genome includes genes for an acetyl-CoA pathway, but lacks genes encoding methanogenesis enzymes such as methyl-coenzyme M reductase, heterodisulfide reductases and hydrogenases. In situ transcriptomic analyses reveal high expression of a multi-heme c-type cytochrome, and heterologous expression of this protein in a model bacterium demonstrates that it is capable of accepting electrons. Our results suggest that Met12, within the order Methanocellales, is not a methanogen but a CO2-reducing, electron-fueled acetogen without electron bifurcation.
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Affiliation(s)
- Shino Suzuki
- Geobiology and Astrobiology Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama, Japan.
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, Kanagawa, Japan.
- School of Physical Sciences, SOKENDAI (Graduate University for Advanced Studies), Sagamihara, Kanagawa, Japan.
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine and Earth Science and Technology (JAMSTEC), Yokosuka, Kanagawa, Japan.
| | - Shun'ichi Ishii
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine and Earth Science and Technology (JAMSTEC), Yokosuka, Kanagawa, Japan.
| | - Grayson L Chadwick
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Yugo Tanaka
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan
| | - Atsushi Kouzuma
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan
| | - Kazuya Watanabe
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan
| | - Fumio Inagaki
- Advanced Institute for Marine Ecosystem Change (WPI-AIMEC), JAMSTEC, Yokohama, Kanagawa, Japan
- Department of Earth Science, Graduate School of Science, Tohoku University, Sendai, Miyagi, Japan
| | - Mads Albertsen
- Center for Microbial Communities, Aalborg University, Aalborg, Denmark
| | - Per H Nielsen
- Center for Microbial Communities, Aalborg University, Aalborg, Denmark
| | - Kenneth H Nealson
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
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8
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Musat F, Kjeldsen KU, Rotaru AE, Chen SC, Musat N. Archaea oxidizing alkanes through alkyl-coenzyme M reductases. Curr Opin Microbiol 2024; 79:102486. [PMID: 38733792 DOI: 10.1016/j.mib.2024.102486] [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: 02/06/2024] [Revised: 04/24/2024] [Accepted: 04/24/2024] [Indexed: 05/13/2024]
Abstract
This review synthesizes recent discoveries of novel archaea clades capable of oxidizing higher alkanes, from volatile ones like ethane to longer-chain alkanes like hexadecane. These archaea, termed anaerobic multicarbon alkane-oxidizing archaea (ANKA), initiate alkane oxidation using alkyl-coenzyme M reductases, enzymes similar to the methyl-coenzyme M reductases of methanogenic and anaerobic methanotrophic archaea (ANME). The polyphyletic alkane-oxidizing archaea group (ALOX), encompassing ANME and ANKA, harbors increasingly complex alkane degradation pathways, correlated with the alkane chain length. We discuss the evolutionary trajectory of these pathways emphasizing metabolic innovations and the acquisition of metabolic modules via lateral gene transfer. Additionally, we explore the mechanisms by which archaea couple alkane oxidation with the reduction of electron acceptors, including electron transfer to partner sulfate-reducing bacteria (SRB). The phylogenetic and functional constraints that shape ALOX-SRB associations are also discussed. We conclude by highlighting the research needs in this emerging research field and its potential applications in biotechnology.
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Affiliation(s)
- Florin Musat
- Department of Biology, Section for Microbiology, Aarhus University, Aarhus, Denmark; Department of Molecular Biology and Biotechnology, Faculty of Biology and Geology, Babeş-Bolyai University, Cluj-Napoca, Romania.
| | - Kasper U Kjeldsen
- Department of Biology, Section for Microbiology, Aarhus University, Aarhus, Denmark
| | - Amelia E Rotaru
- Department of Biology, Nordic Center for Earth Evolution, University of Southern Denmark, Odense, Denmark
| | - Song-Can Chen
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna A-1030, Austria
| | - Niculina Musat
- Department of Biology, Section for Microbiology, Aarhus University, Aarhus, Denmark
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9
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Schwarz IA, Alsaqri B, Lekbach Y, Henry K, Gorman S, Woodard T, Dion L, Real L, Holmes DE, Smith JA, Lovley DR. Lack of physiological evidence for cytochrome filaments functioning as conduits for extracellular electron transfer. mBio 2024; 15:e0069024. [PMID: 38717196 PMCID: PMC11077965 DOI: 10.1128/mbio.00690-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 03/08/2024] [Indexed: 05/12/2024] Open
Abstract
Extracellular cytochrome filaments are proposed to serve as conduits for long-range extracellular electron transfer. The primary functional physiological evidence has been the reported inhibition of Geobacter sulfurreducens Fe(III) oxide reduction when the gene for the filament-forming cytochrome OmcS is deleted. Here we report that the OmcS-deficient strain from that original report reduces Fe(III) oxide as well as the wild-type, as does a triple mutant in which the genes for the other known filament-forming cytochromes were also deleted. The triple cytochrome mutant displayed filaments with the same 3 nm diameter morphology and conductance as those produced by Escherichia coli heterologously expressing the G. sulfurreducens PilA pilin gene. Fe(III) oxide reduction was inhibited when the pilin gene in cytochrome-deficient mutants was modified to yield poorly conductive 3 nm diameter filaments. The results are consistent with the concept that 3 nm diameter electrically conductive pili (e-pili) are required for G. sulfurreducens long-range extracellular electron transfer. In contrast, rigorous physiological functional evidence is lacking for cytochrome filaments serving as conduits for long-range electron transport. IMPORTANCE Unraveling microbial extracellular electron transfer mechanisms has profound implications for environmental processes and advancing biological applications. This study on Geobacter sulfurreducens challenges prevailing beliefs on cytochrome filaments as crucial components thought to facilitate long-range electron transport. The discovery of an OmcS-deficient strain's unexpected effectiveness in Fe(III) oxide reduction prompted a reevaluation of the key conduits for extracellular electron transfer. By exploring the impact of genetic modifications on G. sulfurreducens' performance, this research sheds light on the importance of 3-nm diameter electrically conductive pili in Fe(III) oxide reduction. Reassessing these mechanisms is essential for uncovering the true drivers of extracellular electron transfer in microbial systems, offering insights that could revolutionize applications across diverse fields.
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Affiliation(s)
- Ingrid A. Schwarz
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, Connecticut, USA
| | - Baha Alsaqri
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, Connecticut, USA
| | - Yassir Lekbach
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Kathryn Henry
- Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts, USA
| | - Sydney Gorman
- Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts, USA
| | - Trevor Woodard
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Laura Dion
- Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts, USA
| | - Lauren Real
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, Connecticut, USA
| | - Dawn E. Holmes
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
- Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts, USA
| | - Jessica A. Smith
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, Connecticut, USA
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Derek R. Lovley
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
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10
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Guberman-Pfeffer MJ. To be or not to be a cytochrome: electrical characterizations are inconsistent with Geobacter cytochrome 'nanowires'. Front Microbiol 2024; 15:1397124. [PMID: 38633696 PMCID: PMC11021709 DOI: 10.3389/fmicb.2024.1397124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 03/21/2024] [Indexed: 04/19/2024] Open
Abstract
Geobacter sulfurreducens profoundly shapes Earth's biogeochemistry by discharging respiratory electrons to minerals and other microbes through filaments of a two-decades-long debated identity. Cryogenic electron microscopy has revealed filaments of redox-active cytochromes, but the same filaments have exhibited hallmarks of organic metal-like conductivity under cytochrome denaturing/inhibiting conditions. Prior structure-based calculations and kinetic analyses on multi-heme proteins are synthesized herein to propose that a minimum of ~7 cytochrome 'nanowires' can carry the respiratory flux of a Geobacter cell, which is known to express somewhat more (≥20) filaments to increase the likelihood of productive contacts. By contrast, prior electrical and spectroscopic structural characterizations are argued to be physiologically irrelevant or physically implausible for the known cytochrome filaments because of experimental artifacts and sample impurities. This perspective clarifies our mechanistic understanding of physiological metal-microbe interactions and advances synthetic biology efforts to optimize those interactions for bioremediation and energy or chemical production.
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11
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Shi T, Sun D, Dang Y, Xue Y, Liu X. Enhancement of electron transfer via magnetite in nitrite-dependent anaerobic methane oxidation system. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 357:120843. [PMID: 38588621 DOI: 10.1016/j.jenvman.2024.120843] [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: 01/18/2024] [Revised: 03/02/2024] [Accepted: 04/02/2024] [Indexed: 04/10/2024]
Abstract
Nitrite-dependent anaerobic methane oxidation (n-DAMO) is a novel denitrification process that simultaneously further removes and utilizes methane from anaerobic effluent from wastewater treatment plants. However, the metabolic activity of n-DAMO bacteria is relative low for practical application. In this study, conductive magnetite was added into lab-scale sequencing batch reactor inoculated with n-DAMO bacteria to study the influence on n-DAMO process. With magnetite amendment, the nitrogen removal rate could reach 34.9 mg N·L-1d-1, nearly 2.5 times more than that of control group. Magnetite significantly facilitated the interspecies electron transfer and built electrically connected community with high capacitance. Enzymatic activities of electron transport chain were significantly elevated. Functional gene expression and enzyme activities associated with nitrogen and methane metabolism had been highly up-regulated. These results not only propose a useful strategy in n-DAMO application but also provide insights into the stimulating mechanism of magnetite in n-DAMO process.
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Affiliation(s)
- Tianjing Shi
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Beijing Key Laboratory for Source Control Technology of Water Pollution, Engineering Research Center for Water Pollution Source Control and Eco-remediation, Beijing Forestry University, Beijing, 100083, China.
| | - Dezhi Sun
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Beijing Key Laboratory for Source Control Technology of Water Pollution, Engineering Research Center for Water Pollution Source Control and Eco-remediation, Beijing Forestry University, Beijing, 100083, China.
| | - Yan Dang
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Beijing Key Laboratory for Source Control Technology of Water Pollution, Engineering Research Center for Water Pollution Source Control and Eco-remediation, Beijing Forestry University, Beijing, 100083, China.
| | - Yiting Xue
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Beijing Key Laboratory for Source Control Technology of Water Pollution, Engineering Research Center for Water Pollution Source Control and Eco-remediation, Beijing Forestry University, Beijing, 100083, China.
| | - Xinying Liu
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Beijing Key Laboratory for Source Control Technology of Water Pollution, Engineering Research Center for Water Pollution Source Control and Eco-remediation, Beijing Forestry University, Beijing, 100083, China.
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12
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Portela PC, Shipps CC, Shen C, Srikanth V, Salgueiro CA, Malvankar NS. Widespread extracellular electron transfer pathways for charging microbial cytochrome OmcS nanowires via periplasmic cytochromes PpcABCDE. Nat Commun 2024; 15:2434. [PMID: 38509081 PMCID: PMC10954620 DOI: 10.1038/s41467-024-46192-0] [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: 08/04/2023] [Accepted: 02/19/2024] [Indexed: 03/22/2024] Open
Abstract
Extracellular electron transfer (EET) via microbial nanowires drives globally-important environmental processes and biotechnological applications for bioenergy, bioremediation, and bioelectronics. Due to highly-redundant and complex EET pathways, it is unclear how microbes wire electrons rapidly (>106 s-1) from the inner-membrane through outer-surface nanowires directly to an external environment despite a crowded periplasm and slow (<105 s-1) electron diffusion among periplasmic cytochromes. Here, we show that Geobacter sulfurreducens periplasmic cytochromes PpcABCDE inject electrons directly into OmcS nanowires by binding transiently with differing efficiencies, with the least-abundant cytochrome (PpcC) showing the highest efficiency. Remarkably, this defined nanowire-charging pathway is evolutionarily conserved in phylogenetically-diverse bacteria capable of EET. OmcS heme reduction potentials are within 200 mV of each other, with a midpoint 82 mV-higher than reported previously. This could explain efficient EET over micrometres at ultrafast (<200 fs) rates with negligible energy loss. Engineering this minimal nanowire-charging pathway may yield microbial chassis with improved performance.
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Affiliation(s)
- Pilar C Portela
- Microbial Sciences Institute, Yale University, West Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Catharine C Shipps
- Microbial Sciences Institute, Yale University, West Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Cong Shen
- Microbial Sciences Institute, Yale University, West Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Vishok Srikanth
- Microbial Sciences Institute, Yale University, West Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Carlos A Salgueiro
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal.
- UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal.
| | - Nikhil S Malvankar
- Microbial Sciences Institute, Yale University, West Haven, CT, USA.
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA.
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13
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Zhao S, Zhu S, Liu S, Song G, Zhao J, Liu R, Liu H, Qu J. Quorum Sensing Enhances Direct Interspecies Electron Transfer in Anaerobic Methane Production. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:2891-2901. [PMID: 38308618 DOI: 10.1021/acs.est.3c08503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2024]
Abstract
Direct interspecies electron transfer (DIET) provides an innovative way to achieve efficient methanogenesis, and this study proposes a new approach to upregulate the DIET pathway by enhancing quorum sensing (QS). Based on long-term reactor performance, QS enhancement achieved more vigorous methanogenesis with 98.7% COD removal efficiency. In the control system, methanogenesis failure occurred at the accumulated acetate of 7420 mg of COD/L and lowered pH of 6.04, and a much lower COD removal of 41.9% was observed. The more significant DIET in QS-enhancing system was supported by higher expression of conductive pili and the c-Cyts cytochrome secretion-related genes, resulting in 12.7- and 10.3-fold improvements. Moreover, QS enhancement also improved the energy production capability, with the increase of F-type and V/A-type ATPase expression by 6.3- and 4.2-fold, and this effect probably provided more energy for nanowires and c-Cyts cytochrome secretion. From the perspective of community structure, QS enhancement increased the abundance of Methanosaeta and Geobacter from 54.3 and 17.6% in the control to 63.0 and 33.8%, respectively. Furthermore, the expression of genes involved in carbon dioxide reduction and alcohol dehydrogenation increased by 0.6- and 7.1-fold, respectively. Taken together, this study indicates the positive effects of QS chemicals to stimulate DIET and advances the understanding of the DIET methanogenesis involved in environments such as anaerobic digesters and sediments.
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Affiliation(s)
- Shunan Zhao
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Shaoqing Zhu
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Suo Liu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Ge Song
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
- Key Laboratory of Drinking Water Science and Technology, Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Jing Zhao
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Ruiping Liu
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Huijuan Liu
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Jiuhui Qu
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
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14
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Lin S, Tang W, Xiao Y, Zan F, Liu X, Chen G, Hao T. Sulfur bacteria-reinforced microbial electrochemical denitrification. BIORESOURCE TECHNOLOGY 2024; 393:130121. [PMID: 38029802 DOI: 10.1016/j.biortech.2023.130121] [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: 10/06/2023] [Revised: 11/21/2023] [Accepted: 11/26/2023] [Indexed: 12/01/2023]
Abstract
Two limiting factors of microbial electrochemical denitrification (MED) are the abundance and efficiency of the functional microorganisms. To supply these microorganisms, MED systems are inoculated with denitrifying sludge, but such method has much room for improvement. This study compared MED inoculated with autotrophic denitrifying inoculum (ADI) versus with heterotrophic denitrifying inoculum (HDI). ADI exhibited electroactivity for 50% less of timethan HDI. The denitrification efficiency of the ADI biocathode was42% higherthan that of the HDI biocathode. The HDI biocathode had high levels of polysaccharides while the ADI biocathode was rich in proteins, suggesting that two biocathodes may achieveMED but via differentpathways. Microbial communities of two biocathodes indicated MED of HDI biocathode may rely on interspecies electron transfer, whereas sulfur bacteria of ADI biocathode take electrons directly from the cathode to achieve MED. Utilizing autotrophic sulfur-oxidizing denitrifiers, this study offers a strategy for enhancing MED.
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Affiliation(s)
- Sen Lin
- Department of Civil and Environmental Engineering, Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution (Hong Kong Branch) and Water Technology Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau
| | - Wentao Tang
- Department of Civil and Environmental Engineering, Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution (Hong Kong Branch) and Water Technology Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau
| | - Yihang Xiao
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau
| | - Feixiang Zan
- School of Environmental Science and Engineering, Low-Carbon Water Environment Technology Center (HUST-SUKE), Key Laboratory of Water and Wastewater Treatment, MOHURD, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoming Liu
- School of Materials and Environment Engineering, Shenzhen Polytechnic, Shenzhen, China
| | - Guanghao Chen
- Department of Civil and Environmental Engineering, Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution (Hong Kong Branch) and Water Technology Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Tianwei Hao
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau.
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15
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Baquero DP, Bignon EA, Krupovic M. Pleomorphic viruses establish stable relationship with marine hyperthermophilic archaea. THE ISME JOURNAL 2024; 18:wrae008. [PMID: 38366050 PMCID: PMC10919331 DOI: 10.1093/ismejo/wrae008] [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: 09/14/2023] [Revised: 12/09/2023] [Accepted: 01/18/2024] [Indexed: 02/18/2024]
Abstract
Non-lytic viruses with enveloped pleomorphic virions (family Pleolipoviridae) are ubiquitous in hypersaline environments across the globe and are associated with nearly all major lineages of halophilic archaea. However, their existence in other ecosystems remains largely unknown. Here, we show that evolutionarily-related viruses also infect hyperthermophilic archaea thriving in deep-sea hydrothermal vents. Archaeoglobus veneficus pleomorphic virus 1 (AvPV1), the first virus described for any member of the class Archaeoglobi, encodes a morphogenetic module typical of pleolipoviruses, including the characteristic VP4-like membrane fusion protein. We show that AvPV1 is a non-lytic virus chronically produced in liquid cultures without substantially affecting the growth dynamics of its host with a stable virus-to-host ratio of ~1. Mining of genomic and metagenomic databases revealed broad distribution of AvPV1-like viruses in geographically remote hydrothermal vents. Comparative genomics, coupled with phylogenetic analysis of VP4-like fusogens revealed deep divergence of pleomorphic viruses infecting halophilic, methanogenic, and hyperthermophilic archaea, signifying niche separation and coevolution of the corresponding virus-host pairs. Hence, we propose a new virus family, "Thalassapleoviridae," for classification of the marine hyperthermophilic virus AvPV1 and its relatives. Collectively, our results provide insights into the diversity and evolution of pleomorphic viruses beyond hypersaline environments.
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Affiliation(s)
- Diana P Baquero
- Institut Pasteur, Université Paris Cité, Archaeal Virology Unit, Paris 75015, France
| | - Eduardo A Bignon
- Institut Pasteur, Université Paris Cité, Archaeal Virology Unit, Paris 75015, France
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, Archaeal Virology Unit, Paris 75015, France
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16
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Liu X, Ye Y, Yang N, Cheng C, Rensing C, Jin C, Nealson KH, Zhou S. Nonelectroactive clostridium obtains extracellular electron transfer-capability after forming chimera with Geobacter. ISME COMMUNICATIONS 2024; 4:ycae058. [PMID: 38770058 PMCID: PMC11104457 DOI: 10.1093/ismeco/ycae058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 03/25/2024] [Accepted: 04/15/2024] [Indexed: 05/22/2024]
Abstract
Extracellular electron transfer (EET) of microorganisms is a major driver of the microbial growth and metabolism, including reactions involved in the cycling of C, N, and Fe in anaerobic environments such as soils and sediments. Understanding the mechanisms of EET, as well as knowing which organisms are EET-capable (or can become so) is fundamental to electromicrobiology and geomicrobiology. In general, Gram-positive bacteria very seldomly perform EET due to their thick non-conductive cell wall. Here, we report that a Gram-positive Clostridium intestinale (C.i) attained EET-capability for ethanol metabolism only after forming chimera with electroactive Geobacter sulfurreducens (G.s). Mechanism analyses demonstrated that the EET was possible after the cell fusion of the two species was achieved. Under these conditions, the ethanol metabolism pathway of C.i was integrated by the EET pathway of G.s, by which achieved the oxidation of ethanol for the subsequent reduction of extracellular electron acceptors in the coculture. Our study displays a new approach to perform EET for Gram-positive bacteria via recruiting the EET pathway of an electroactive bacterium, which suggests a previously unanticipated prevalence of EET in the microbial world. These findings also provide new perspectives to understand the energetic coupling between bacterial species and the ecology of interspecies mutualisms.
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Affiliation(s)
- Xing Liu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Yin Ye
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Naiming Yang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Chen Cheng
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Christopher Rensing
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Chao Jin
- School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, Guangdong 510006, China
| | - Kenneth H Nealson
- Department of Earth Science & Biological Sciences, University of Southern California, Los Angeles, CA 91030, United States
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
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17
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Li L, Liu Z, Meng D, Liu Y, Liu T, Jiang C, Yin H. Sequence similarity network and protein structure prediction offer insights into the evolution of microbial pathways for ferrous iron oxidation. mSystems 2023; 8:e0072023. [PMID: 37768051 PMCID: PMC10654088 DOI: 10.1128/msystems.00720-23] [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: 07/11/2023] [Accepted: 08/09/2023] [Indexed: 09/29/2023] Open
Abstract
IMPORTANCE Microbial Fe(II) oxidation is a crucial process that harnesses and converts the energy available in Fe, contributing significantly to global element cycling. However, there are still many aspects of this process that remain unexplored. In this study, we utilized a combination of comparative genomics, sequence similarity network analysis, and artificial intelligence-driven structure modeling methods to address the lack of structural information on Fe(II) oxidation proteins and offer a comprehensive perspective on the evolution of Fe(II) oxidation pathways. Our findings suggest that several microbial Fe(II) oxidation pathways currently known may have originated within classes Gammaproteobacteria and Betaproteobacteria.
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Affiliation(s)
- Liangzhi Li
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Zhenghua Liu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Delong Meng
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Yongjun Liu
- Hunan Tobacco Science Institute, Changsha, China
| | - Tianbo Liu
- Hunan Tobacco Science Institute, Changsha, China
| | - Chengying Jiang
- University of Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Huaqun Yin
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
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18
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Niman CM, Sukenik N, Dang T, Nwachukwu J, Thirumurthy MA, Jones AK, Naaman R, Santra K, Das TK, Paltiel Y, Baczewski LT, El-Naggar MY. Bacterial extracellular electron transfer components are spin selective. J Chem Phys 2023; 159:145101. [PMID: 37811828 DOI: 10.1063/5.0154211] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 08/01/2023] [Indexed: 10/10/2023] Open
Abstract
Metal-reducing bacteria have adapted the ability to respire extracellular solid surfaces instead of soluble oxidants. This process requires an electron transport pathway that spans from the inner membrane, across the periplasm, through the outer membrane, and to an external surface. Multiheme cytochromes are the primary machinery for moving electrons through this pathway. Recent studies show that the chiral-induced spin selectivity (CISS) effect is observable in some of these proteins extracted from the model metal-reducing bacteria, Shewanella oneidensis MR-1. It was hypothesized that the CISS effect facilitates efficient electron transport in these proteins by coupling electron velocity to spin, thus reducing the probability of backscattering. However, these studies focused exclusively on the cell surface electron conduits, and thus, CISS has not been investigated in upstream electron transfer components such as the membrane-associated MtrA, or periplasmic proteins such as small tetraheme cytochrome (STC). By using conductive probe atomic force microscopy measurements of protein monolayers adsorbed onto ferromagnetic substrates, we show that electron transport is spin selective in both MtrA and STC. Moreover, we have determined the spin polarization of MtrA to be ∼77% and STC to be ∼35%. This disparity in spin polarizations could indicate that spin selectivity is length dependent in heme proteins, given that MtrA is approximately two times longer than STC. Most significantly, our study indicates that spin-dependent interactions affect the entire extracellular electron transport pathway.
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Affiliation(s)
- Christina M Niman
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, USA
| | - Nir Sukenik
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, USA
| | - Tram Dang
- Department of Biological Sciences, University of Southern California, Los Angeles, California 91030, USA
| | - Justus Nwachukwu
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
| | - Miyuki A Thirumurthy
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
| | - Anne K Jones
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
| | - Ron Naaman
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Kakali Santra
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Tapan K Das
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yossi Paltiel
- Institute of Applied Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | | | - Mohamed Y El-Naggar
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, USA
- Department of Biological Sciences, University of Southern California, Los Angeles, California 91030, USA
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
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19
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Khomyakova MA, Merkel AY, Slobodkin AI, Sorokin DY. Phenotypic and genomic characterization of the first alkaliphilic aceticlastic methanogens and proposal of a novel genus Methanocrinis gen.nov. within the family Methanotrichaceae. Front Microbiol 2023; 14:1233691. [PMID: 37886072 PMCID: PMC10598746 DOI: 10.3389/fmicb.2023.1233691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 09/12/2023] [Indexed: 10/28/2023] Open
Abstract
Highly purified cultures of alkaliphilic aceticlastic methanogens were collected for the first time using methanogenic enrichments with acetate from a soda lake and a terrestrial mud volcano. The cells of two strains were non-motile rods forming filaments. The mud volcano strain M04Ac was alkalitolerant, with the pH range for growth from 7.5 to 10.0 (optimum at 9.0), while the soda lake strain Mx was an obligate alkaliphile growing in the pH range 7.7-10.2 (optimum 9.3-9.5) in the presence of optimally 0.2-0.3 M total Na+. Genomes of both strains encoded all enzymes required for aceticlastic methanogenesis and different mechanisms of (halo)alkaline adaptations, including ectoine biosynthesis, which is the first evidence for the formation of this osmoprotectant in archaea. According to 16S rRNA gene phylogeny, the strains possessed 98.3-98.9% sequence identity and belonged to the obligately aceticlastic genus Methanothrix with M. harundinaceae as the most closely related species. However, a more advanced phylogenomic reconstruction based on 122 conserved single-copy archaeal protein-coding marker genes clearly indicated a polyphyletic origin of the species included in the genus Methanothrix. We propose to reclassify Methanothrix harrundinacea (type strain 8AcT) into a new genus, Methanocrinis gen. nov., with the type species Methanocrinis harrundinaceus comb. nov. We also propose under SeqCode the complete genome sequences of strain MxTs (GCA_029167045.1) and strain M04AcTs (GCA_029167205.1) as nomenclatural types of Methanocrinis natronophilus sp. nov. and Methanocrinis alkalitolerans sp. nov., respectively, which represent other species of the novel genus. This work demonstrates that the low energy aceticlastic methanogenesis may function at extreme conditions present in (halo)alkaline habitats.
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Affiliation(s)
- Maria A. Khomyakova
- Winogradsky Institute of Microbiology, FRC Biotechnology Russian Academy of Sciences, Moscow, Russia
| | - Alexander Y. Merkel
- Winogradsky Institute of Microbiology, FRC Biotechnology Russian Academy of Sciences, Moscow, Russia
| | - Alexander I. Slobodkin
- Winogradsky Institute of Microbiology, FRC Biotechnology Russian Academy of Sciences, Moscow, Russia
| | - Dimitry Y. Sorokin
- Winogradsky Institute of Microbiology, FRC Biotechnology Russian Academy of Sciences, Moscow, Russia
- Department of Biotechnology, Delft University of Technology, Delft, Netherlands
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20
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Guberman-Pfeffer MJ. Structural Determinants of Redox Conduction Favor Robustness over Tunability in Microbial Cytochrome Nanowires. J Phys Chem B 2023; 127:7148-7161. [PMID: 37552847 DOI: 10.1021/acs.jpcb.3c02912] [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] [Indexed: 08/10/2023]
Abstract
Structural determinants of a 103-fold variation in electrical conductivity for helical homopolymers of tetra-, hexa-, and octa-heme cytochromes (named Omc- E, S, and Z, respectively) from Geobacter sulfurreducens are investigated with the Pathways model for electron tunneling, classical molecular dynamics, and hybrid quantum/classical molecular mechanics. Thermally averaged electronic couplings for through-space heme-to-heme electron transfer in the "nanowires" computed with density functional theory are ≤0.015 eV. Pathways analyses also indicate that couplings match within a factor of 5 for all "nanowires", but some alternative tunneling routes are found involving covalent protein backbone bonds (Omc- S and Z) or propionic acid-ligating His H-bonds on adjacent hemes (OmcZ). Reorganization energies computed from electrostatic vertical energy gaps or a version of the Marcus continuum expression parameterized on the total (donor + acceptor) solvent-accessible surface area typically agree within 20% and fall within the range 0.48-0.98 eV. Reaction free energies in all three "nanowires" are ≤|0.28| eV, even though Coulombic interactions primarily tune the site redox energies by 0.7-1.2 eV. Given the conserved energetic parameters, redox conductivity differs by < 103-fold among the cytochrome "nanowires". Redox currents do not exceed 3.0 × 10-3 pA at a physiologically relevant 0.1 V bias, with the slowest electron transfers being on a (μs) timescale much faster than typical (ms) enzymatic turnovers. Thus, the "nanowires" are proposed to be functionally robust to variations in structure that provide a habitat-customized protein interface. The 30 pA to 30 nA variation in conductivity previously reported from atomic force microscopy experiments is not intrinsic to the structures and/or does not result from the physiologically relevant redox conduction mechanism.
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Affiliation(s)
- Matthew J Guberman-Pfeffer
- Department of Molecular Biophysics and Biochemistry, Yale University, 333 Cedar Street, New Haven, Connecticut 06510, United States
- Microbial Sciences Institute, Yale University, 840 West Campus Drive, West Haven, Connecticut 06516, United States
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21
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Liu J, Eastep GN, Cvirkaite-Krupovic V, Rich-New ST, Kreutzberger MAB, Egelman EH, Krupovic M, Wang F. Two dramatically distinct archaeal type IV pili structures formed by the same pilin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.07.552285. [PMID: 37609343 PMCID: PMC10441282 DOI: 10.1101/2023.08.07.552285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Type IV pili (T4P) represent one of the most common varieties of surface appendages in archaea. These filaments, assembled from relatively small pilin proteins, can be many microns long and serve diverse functions, including adhesion, biofilm formation, motility, and intercellular communication. Using cryo-electron microscopy (cryo-EM), we determined atomic structures of two dramatically different T4P from Saccharolobus islandicus REY15A. Unexpectedly, both pili were assembled from the same pilin protein but under different growth conditions. One filament, denoted mono-pilus, conforms to canonical archaeal T4P structures where all subunits are equivalent, whereas in the other filament, the tri-pilus, the same protein exists in three different conformations. The three conformations involve different orientations of the outer immunoglobulin (Ig)-like domains, mediated by a very flexible linker, and all three of these conformations are very different from the single conformation found in the mono-pilus. Remarkably, the outer domains rotate nearly 180° between the mono- and tri-pilus conformations, formally similar to what has been shown for outer domains in bacterial flagellar filaments, despite lack of homology between bacterial flagella and archaeal T4P. Interestingly, both forms of pili require the same ATPase and TadC-like membrane pore for assembly, indicating that the same secretion system can produce structurally very different filaments. However, the expression of the ATPase and TadC genes was significantly different under the conditions yielding mono- and tri-pili. While archaeal T4P are homologs of archaeal flagellar filaments, our results show that in contrast to the rigid supercoil that the flagellar filaments must adopt to serve as helical propellers, archaeal T4P are likely to have fewer constraints on their structure and enjoy more internal degrees of freedom.
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