A unique aromatic residue modulates the redox range of a periplasmic multiheme cytochrome from Geobacter metallireducens

ABSTRACTAccurately predicting the interactions between microbial metabolism and the physical subsurface environment is necessary to enhance subsurface energy development, soil and groundwater cleanup, and carbon management. This study was an initial attempt to confirm the metabolic functional roles within anin silicomodel using environmental proteomic data collected during field experiments. Shotgun global proteomics data collected during a subsurface biostimulation experiment were used to validate a genome-scale metabolic model ofGeobacter metallireducens—specifically, the ability of the metabolic model to predict metal reduction, biomass yield, and growth rate under dynamic field conditions. The constraint-basedin silicomodelof G. metallireducensrelates an annotated genome sequence to the physiological functions with 697 reactions controlled by 747 enzyme-coding genes. Proteomic analysis showed that 180 of the 637G. metallireducensproteins detected during the 2008 experiment were associated with specific metabolic reactions in thein silicomodel. When the field-calibrated Fe(III) terminal electron acceptor process reaction in a reactive transport model for the field experiments was replaced with the genome-scale model, the model predicted that the largest metabolic fluxes through thein silicomodel reactions generally correspond to the highest abundances of proteins that catalyze those reactions. Central metabolism predicted by the model agrees well with protein abundance profiles inferred from proteomic analysis. Model discrepancies with the proteomic data, such as the relatively low abundances of proteins associated with amino acid transport and metabolism, revealed pathways or flux constraints in thein silicomodel that could be updated to more accurately predict metabolic processes that occur in the subsurface environment.

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Solvent and substituent effects on rearrangement of 4-(4-X-phenyl)-2,7-dioxa-3-azabicyclo[3,3,0]oct-3-enes

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19851971 ◽

1985 ◽

Vol 50 (9) ◽

pp. 1971-1981 ◽

Cited By ~ 4

Author(s):

Lubor Fišera ◽

Marta Konopíková ◽

Ladislav Štibrányi ◽

Hans-Joachim Timpe

Keyword(s):

Substituent Effects ◽

Quantum Yields ◽

Polar Solvents ◽

Aromatic Residue ◽

Product Ratio ◽

Oxazoline Derivatives ◽

Oxazine Derivatives

Preparation of the title compounds V is described. They give, on irradiation, the 2,3-dihydro-6H-1,3-oxazine derivatives VI as the main products besides the tetrahydrofuro[3,4-d]oxazoline derivatives VII. The VI to VII product ratio depends on the substituent bound to the aromatic residue. Polar solvents favour formation of the VI derivatives in the order Cl >H > CH3. In non-polar solvents the proportion of VII is increased. The quantum yields of the photoreaction vary within the limits from 0.006 to 0.04 (H >F > Cl > CH3 > OCH3).

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Direct Interspecies Electron Transfer between Geobacter metallireducens and Methanosarcina barkeri

Applied and Environmental Microbiology ◽

10.1128/aem.00895-14 ◽

2014 ◽

Vol 80 (15) ◽

pp. 4599-4605 ◽

Cited By ~ 398

Author(s):

Amelia-Elena Rotaru ◽

Pravin Malla Shrestha ◽

Fanghua Liu ◽

Beatrice Markovaite ◽

Shanshan Chen ◽

...

Keyword(s):

Electron Transfer ◽

Model Organism ◽

Methanosarcina Barkeri ◽

Physical Contact ◽

Acetate Metabolism ◽

Geobacter Metallireducens ◽

Content Type ◽

Direct Interspecies Electron Transfer ◽

Interspecies Electron Transfer ◽

Effective Form

ABSTRACTDirect interspecies electron transfer (DIET) is potentially an effective form of syntrophy in methanogenic communities, but little is known about the diversity of methanogens capable of DIET. The ability ofMethanosarcina barkerito participate in DIET was evaluated in coculture withGeobacter metallireducens. Cocultures formed aggregates that shared electrons via DIET during the stoichiometric conversion of ethanol to methane. Cocultures could not be initiated with a pilin-deficientG. metallireducensstrain, suggesting that long-range electron transfer along pili was important for DIET. Amendments of granular activated carbon permitted the pilin-deficientG. metallireducensisolates to share electrons withM. barkeri, demonstrating that this conductive material could substitute for pili in promoting DIET. WhenM. barkeriwas grown in coculture with the H2-producingPelobacter carbinolicus, incapable of DIET,M. barkeriutilized H2as an electron donor but metabolized little of the acetate thatP. carbinolicusproduced. This suggested that H2, but not electrons derived from DIET, inhibited acetate metabolism.P. carbinolicus-M. barkericocultures did not aggregate, demonstrating that, unlike DIET, close physical contact was not necessary for interspecies H2transfer.M. barkeriis the second methanogen found to accept electrons via DIET and the first methanogen known to be capable of using either H2or electrons derived from DIET for CO2reduction. Furthermore,M. barkeriis genetically tractable, making it a model organism for elucidating mechanisms by which methanogens make biological electrical connections with other cells.

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Photoexcited flavins and pterins as electron injectors for multiheme cytochrome

Doklady Biochemistry and Biophysics ◽

10.1134/s1607672909010050 ◽

2009 ◽

Vol 424 (1) ◽

pp. 16-19

Author(s):

M. S. Kritsky ◽

T. A. Lyudnikova ◽

E. S. Slutsky ◽

A. A. Filimonenkov ◽

T. V. Tikhonova ◽

...

Keyword(s):

Multiheme Cytochrome

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Exploration of CH⋯π mediated stacking interactions in saccharide: aromatic residue complexes through conformational sampling

Carbohydrate Research ◽

10.1016/j.carres.2012.08.015 ◽

2012 ◽

Vol 361 ◽

pp. 133-140 ◽

Cited By ~ 13

Author(s):

Manju Kumari ◽

Raghavan B. Sunoj ◽

Petety V. Balaji

Keyword(s):

Conformational Sampling ◽

Stacking Interactions ◽

Aromatic Residue

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The triheme cytochrome PpcF from Geobacter metallireducens exhibits distinct redox properties

FEBS Open Bio ◽

10.1002/2211-5463.12505 ◽

2018 ◽

Vol 8 (12) ◽

pp. 1897-1910 ◽

Cited By ~ 1

Author(s):

Marisa R. Ferreira ◽

Joana M. Dantas ◽

Carlos A. Salgueiro

Keyword(s):

Redox Properties ◽

Geobacter Metallireducens

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Effect of Geobacter metallireducens nanowire on electron transfer efficiency in MFC

10.1101/2021.07.14.452433 ◽

2021 ◽

Author(s):

Shunliang Liu ◽

feng ya li ◽

li hao ran

Keyword(s):

Electron Transfer ◽

Electrochemical Measurement ◽

Inhibitory Effect ◽

Transfer Efficiency ◽

Maximum Output ◽

Current Response ◽

Electron Mediator ◽

Geobacter Metallireducens ◽

Culture Process ◽

Double Chamber

Inhibitory effect of electron mediator AQDS on Geobacter metallireducens nanowire in microbial fuel cell (MFC) was studied. In the culture process of G. metallireducens with Fe(OH)3 as electron acceptor, the concentration of reduction product Fe (II) in solution without AQDS is higher than that with AQDS after 10 days, due to the formation of microbial nanowires. The effects of nanowire on electron transfer efficiency and power generation characteristic were studied using double chamber MFC reactor. The transfer efficiency between biofilm and electrodes was increased by nanowire, which increases maximum output voltage of MFC from 321 mV to 442 mV. The nanowire biofilm electrode has the bigger cyclic voltammetry curve peak, smaller activation resistance and stronger current response signal through electrochemical measurement, which indicated that the nanowire enhanced the electrochemical activity of the electrode.

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Putative Extracellular Electron Transfer in Methanogenic Archaea

Frontiers in Microbiology ◽

10.3389/fmicb.2021.611739 ◽

2021 ◽

Vol 12 ◽

Author(s):

Kailin Gao ◽

Yahai Lu

Keyword(s):

Electron Transfer ◽

Methanogenic Archaea ◽

Methanosarcina Barkeri ◽

Extracellular Electron Transfer ◽

Future Research ◽

Methanosarcina Acetivorans ◽

Geobacter Metallireducens ◽

Methanosarcina Mazei ◽

Current State ◽

Electron Transfers

It has been suggested that a few methanogens are capable of extracellular electron transfers. For instance, Methanosarcina barkeri can directly capture electrons from the coexisting microbial cells of other species. Methanothrix harundinacea and Methanosarcina horonobensis retrieve electrons from Geobacter metallireducens via direct interspecies electron transfer (DIET). Recently, Methanobacterium, designated strain YSL, has been found to grow via DIET in the co-culture with Geobacter metallireducens. Methanosarcina acetivorans can perform anaerobic methane oxidation and respiratory growth relying on Fe(III) reduction through the extracellular electron transfer. Methanosarcina mazei is capable of electromethanogenesis under the conditions where electron-transfer mediators like H2 or formate are limited. The membrane-bound multiheme c-type cytochromes (MHC) and electrically-conductive cellular appendages have been assumed to mediate the extracellular electron transfer in bacteria like Geobacter and Shewanella species. These molecules or structures are rare but have been recently identified in a few methanogens. Here, we review the current state of knowledge for the putative extracellular electron transfers in methanogens and highlight the opportunities and challenges for future research.

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