MacA, a Diheme
            <i>c</i>
            -Type Cytochrome Involved in Fe(III) Reduction by
            <i>Geobacter sulfurreducens</i>

Butler, Jessica; Kaufmann, Franz; Coppi, Maddalena V.; Núñez, Cinthia; Lovley, Derek R.

doi:10.1128/jb.186.12.4042-4045.2004

Cited by 103 publications

(100 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…1c). This result indicated a requirement for periplasmic and/or outer-membrane components for the acetate-dependent reduction of Fe(III) citrate and was in agreement with previous studies, in which deletion of genes coding for a variety of periplasmic or outer membrane proteins impaired Fe(III) citrate reduction (Afkar et al, 2005;Butler et al, 2004;Kim et al, 2005Kim et al, , 2006Leang et al, 2003;Lloyd et al, 2003). Spheroplasts also failed to reduce AQDS with acetate serving as the electron donor (Fig.…”

Section: Fe(iii) Reduction By Spheroplastssupporting

confidence: 80%

“…In contrast, the subcellular localization of the reduction of chelated forms of Fe(III) is not known. Genetic studies conducted in G. sulfurreducens have implicated several periplasmic and outer-membrane cytochromes in Fe(III) citrate reduction (Butler et al, 2004;Kim et al, 2005Kim et al, , 2006Leang et al, 2003;Lloyd et al, 2003), suggesting that the reduction of Fe(III) citrate might occur at the cell surface. Biochemical studies performed in G. sulfurreducens have provided conflicting information regarding the site of Fe(III) chelate reduction.…”

Section: Introductionmentioning

confidence: 99%

“…Due to technical considerations, chelated forms of Fe(III), most often Fe(III) citrate and Fe(III) chelated with nitrilotriacetic acid (Fe(III)-NTA), are frequently used for laboratory studies addressing Fe(III) reduction by Geobacter species (Butler et al, 2004;Ding et al, 2006;Esteve-Nú ñez et al, 2005;Kim et al, 2005Kim et al, , 2006Leang et al, 2003;Lloyd et al, 2003;Methé et al, 2005;Nú ñez et al, 2004Nú ñez et al, , 2006). An understanding of the similarities and differences between the electron transport pathways to Fe(III) citrate and insoluble Fe(III) oxides is, therefore, crucial for determining the environmental relevance of these studies.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Involvement of Geobacter sulfurreducens SfrAB in acetate metabolism rather than intracellular, respiration-linked Fe(III) citrate reduction

et al. 2007

View full text Add to dashboard Cite

A soluble ferric reductase, SfrAB, which catalysed the NADPH-dependent reduction of chelated Fe(III), was previously purified from the dissimilatory Fe(III)-reducing micro-organism Geobacter sulfurreducens, suggesting that reduction of chelated forms of Fe(III) might be cytoplasmic. However, metabolically active spheroplast suspensions could not catalyse acetate-dependent Fe(III) citrate reduction, indicating that periplasmic and/or outer-membrane components were required for Fe(III) citrate reduction. Furthermore, phenotypic analysis of an SfrAB knockout mutant suggested that SfrAB was involved in acetate metabolism rather than respiration-linked Fe(III) reduction. The mutant could not grow via the reduction of either Fe(III) citrate or fumarate when acetate was the electron donor but could grow with either acceptor if either hydrogen or formate served as the electron donor. Following prolonged incubation in acetate : fumarate medium in the absence of hydrogen and formate, an 'acetate-adapted' SfrAB-null strain was isolated that was capable of growth on acetate : fumarate medium but not acetate : Fe(III) citrate medium. Comparison of gene expression in this strain with that of the wild-type revealed upregulation of a potential NADPH-dependent ferredoxin oxidoreductase as well as genes involved in energy generation and amino acid uptake, suggesting that NADPH homeostasis and the tricarboxylic acid (TCA) cycle were perturbed in the 'acetate-adapted' SfrAB-null strain. Membrane and soluble fractions prepared from the 'acetate-adapted' strain were depleted of NADPH-dependent Fe(III), viologen and quinone reductase activities. These results indicate that cytoplasmic, respiration-linked reduction of Fe(III) by SfrAB in vivo is unlikely and suggest that deleting SfrAB may interfere with growth via acetate oxidation by interfering with NADP regeneration.

show abstract

Section: Fe(iii) Reduction By Spheroplastssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Involvement of Geobacter sulfurreducens SfrAB in acetate metabolism rather than intracellular, respiration-linked Fe(III) citrate reduction

et al. 2007

View full text Add to dashboard Cite

show abstract

“…Homologs of macA have also been detected in five additional Geobacteraceae genomes (D. acetoxidans, G. bemidjiensis, G. metallireducens, G. sulfurreducens and strain M21). Deletion of macA in G. sulfurreducens inhibits Fe(III) (Butler et al, 2004) and U(VI) (Shelobolina et al, 2007) reduction. However, this appears to be an indirect effect caused by the fact that the outer-membrane ctype cytochrome, OmcB, is not expressed in the macA-deficient mutant (Kim and Lovley, 2008).…”

Section: Resultsmentioning

confidence: 99%

Transcriptome of Geobacter uraniireducens growing in uranium-contaminated subsurface sediments

et al. 2008

View full text Add to dashboard Cite

To learn more about the physiological state of Geobacter species living in subsurface sediments, heat-sterilized sediments from a uranium-contaminated aquifer in Rifle, Colorado, were inoculated with Geobacter uraniireducens, a pure culture representative of the Geobacter species that predominates during in situ uranium bioremediation at this site. Whole-genome microarray analysis comparing sediment-grown G. uraniireducens with cells grown in defined culture medium indicated that there were 1084 genes that had higher transcript levels during growth in sediments. Thirty-four c-type cytochrome genes were upregulated in the sediment-grown cells, including several genes that are homologous to cytochromes that are required for optimal Fe(III) and U(VI) reduction by G. sulfurreducens. Sediment-grown cells also had higher levels of transcripts, indicative of such physiological states as nitrogen limitation, phosphate limitation and heavy metal stress. Quantitative reverse transcription PCR showed that many of the metabolic indicator genes that appeared to be upregulated in sediment-grown G. uraniireducens also showed an increase in expression in the natural community of Geobacter species present during an in situ uranium bioremediation field experiment at the Rifle site. These results demonstrate that it is feasible to monitor gene expression of a microorganism growing in sediments on a genome scale and that analysis of the physiological status of a pure culture growing in subsurface sediments can provide insights into the factors controlling the physiology of natural subsurface communities.

show abstract

“…After recovery from the boreholes, electrodes were placed at 4°C and shipped by overnight courier for analysis. Prior to analysis, loosely bound material was removed by gentle washing with isotonic buffer [23]. Duplicate biofilm samples were fluorescently stained with either the LIVE/DEAD BacLight bacterial viability kit (L7012, Molecular Probes, Inc., Eugene, OR) or a generic nucleic acid binding stain (Syto9; Molecular Probes) and examined as described [15].…”

Section: Confocal Laser Scanning Microscopy and 16s Rrna Microbial Comentioning

confidence: 99%

Electrode-Based Approach for Monitoring In Situ Microbial Activity During Subsurface Bioremediation

Williams

Nevin

Franks

et al. 2009

Environ. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

Current production by microorganisms colonizing subsurface electrodes and its relationship to substrate availability and microbial activity was evaluated in an aquifer undergoing bioremediation. Borehole graphite anodes were installed downgradient from a region of acetate injection designed to stimulate bioreduction of U(VI); cathodes consisted of graphite electrodes embedded at the ground surface. Significant increases in current density (≤50 mA/m 2 ) tracked delivery of acetate to the electrodes, dropping rapidly when acetate inputs were discontinued. An upgradient control electrode not exposed to acetate produced low, steady currents (≤0.2 mA/m 2 ). Elevated current was strongly correlated with uranium removal but minimal correlation existed with elevated Fe(II). Confocal laser scanning microscopy of electrodes revealed firmly attached biofilms, and analysis of 16S rRNA gene sequences indicated the electrode surfaces were dominated (67-80%) by Geobacter species. This is the first demonstration that electrodes can produce readily detectable currents despite long-range (6 m) separation of anode and cathode, and these results suggest that oxidation of acetate coupled to electron transfer to electrodes by Geobacter species was the primary source of current. Thus it is expected that current production may serve as an effective proxy for monitoring in situ microbial activity in a variety of subsurface anoxic environments.

show abstract

MacA, a Diheme c -Type Cytochrome Involved in Fe(III) Reduction by Geobacter sulfurreducens

Abstract: A 36-kDa diheme c-type cytochrome abundant in Fe(III)-respiring Geobacter sulfurreducens, designated MacA, was more highly expressed during growth with Fe(III) as the electron acceptor than with fumarate.

Cited by 103 publications

References 44 publications

Involvement of Geobacter sulfurreducens SfrAB in acetate metabolism rather than intracellular, respiration-linked Fe(III) citrate reduction

Involvement of Geobacter sulfurreducens SfrAB in acetate metabolism rather than intracellular, respiration-linked Fe(III) citrate reduction

Transcriptome of Geobacter uraniireducens growing in uranium-contaminated subsurface sediments

Electrode-Based Approach for Monitoring In Situ Microbial Activity During Subsurface Bioremediation

Contact Info

Product

Resources

About