The RpoS Sigma Factor in the Dissimilatory Fe(III)-Reducing Bacterium
            <i>Geobacter sulfurreducens</i>

Núñez, Cinthia; Adams, L A; Childers, Susan E.; Lovley, Derek R.

doi:10.1128/jb.186.16.5543-5546.2004

Cited by 30 publications

(24 citation statements)

References 38 publications

(34 reference statements)

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“…Previously we described an RpoS homolog in Geobacter sulfurreducens (44). It was found that RpoS is necessary for survival in stationary phase and upon oxygen exposure as well as for effective reduction of Fe(III) oxides, the primary electron acceptor for the Geobacteraceae in most sedimentary environments.…”

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confidence: 99%

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DNA Microarray and Proteomic Analyses of the RpoS Regulon in Geobacter sulfurreducens

et al. 2006

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The regulon of the sigma factor RpoS was defined in Geobacter sulfurreducens by using a combination of DNA microarray expression profiles and proteomics. An rpoS mutant was examined under steady-state conditions with acetate as an electron donor and fumarate as an electron acceptor and with additional transcriptional profiling using Fe(III) as an electron acceptor. Expression analysis revealed that RpoS acts as both a positive and negative regulator. Many of the RpoS-dependent genes determined play roles in energy metabolism, including the tricarboxylic acid cycle, signal transduction, transport, protein synthesis and degradation, and amino acid metabolism and transport. As expected, RpoS activated genes involved in oxidative stress resistance and adaptation to nutrient limitation. Transcription of the cytochrome c oxidase operon, necessary for G. sulfurreducens growth using oxygen as an electron acceptor, and expression of at least 13 c-type cytochromes, including one previously shown to participate in Fe(III) reduction (MacA), were RpoS dependent. Analysis of a subset of the rpoS mutant proteome indicated that 15 major protein species showed reproducible differences in abundance relative to those of the wild-type strain. Protein identification using mass spectrometry indicated that the expression of seven of these proteins correlated with the microarray data. Collectively, these results indicate that RpoS exerts global effects on G. sulfurreducens physiology and that RpoS is vital to G. sulfurreducens survival under conditions typically encountered in its native subsurface environments.

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“…The rpoS gene encodes a sigma factor, S or RpoS, which is the master regulator of the general stress response. First described for Escherichia coli, homologs of RpoS in the ␥, ␤, and ␦ subclasses of Proteobacteria have since been characterized (23,24,35,44).…”

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DNA Microarray and Proteomic Analyses of the RpoS Regulon in Geobacter sulfurreducens

et al. 2006

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“…In addition to this physiological role, oxygen may also be toxic over certain levels by oxidizing the cytochrome network and blocking the electron transfer. Furthermore the presence of oxygen can generating reactive oxygen species (hydrogen peroxide, superoxide radicals) that can damage cell structure, including membrane, DNA and proteins, in a process referred as oxidative stress [55]. Indeed a current drop was measured in our MEC device when oxygen level was increased to 2 ppm ( Figure S1).…”

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confidence: 94%

Strategies for Reducing the Start-up Operation of Microbial Electrochemical Treatments of Urban Wastewater

et al. 2015

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Abstract:Microbial electrochemical technologies (METs) constitute the core of a number of emerging technologies with a high potential for treating urban wastewater due to a fascinating reaction mechanism-the electron transfer between bacteria and electrodes to transform metabolism into electrical current. In the current work, we focus on the model electroactive microorganism Geobacter sulfurreducens to explore both the design of new start-up procedures and electrochemical operations. Our chemostat-grown plug and play cells, were able to reduce the start-up period by 20-fold while enhancing chemical oxygen demand (COD) removal by more than 6-fold during this period. Moreover, a filter-press based bioreactor was successfully tested for both acetate-supplemented synthetic wastewater and real urban wastewater. This proof-of-concept pre-pilot treatment included a microbial electrolysis cell (MEC) followed in time by a microbial fuel cell (MFC) to finally generate electrical current of ca. 20 A¨m´2 with a power of 10 W¨m´2 while removing 42 g COD day´1¨m´2.The effective removal of acetate suggests a potential use of this modular technology for treating acetogenic wastewater where Geobacter sulfurreducens outcompetes other organisms.

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“…S4), a feature typically exhibited by housekeeping s factors. However, the size of RpoS (B40 kDa) 31 and its binding motif are typical of bacterial s S (Supplementary Figs S4 and S6). Taken together, the lack of auto-regulation and a capability to regulate other s factors further preclude classification of this s S homologue as an alternative housekeeping s factor.…”

Section: Discussionmentioning

confidence: 99%

“…Wild-type G. sulfurreducens (ATCC 51573) and a DrpoS strain 31 were grown under strictly anoxic conditions at 30°C with acetate as electron donor and fumarate or ferric citrate as electron acceptor as previously described 32 . Cell growth was monitored by measuring OD 600 .…”

Section: Methodsmentioning

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Characterizing the interplay between multiple levels of organization within bacterial sigma factor regulatory networks

et al. 2013

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Bacteria contain multiple sigma factors, each targeting diverse, but often overlapping sets of promoters, thereby forming a complex network. The layout and deployment of such a sigma factor network directly impacts global transcriptional regulation and ultimately dictates the phenotype. Here we integrate multi-omic data sets to determine the topology, the operational, and functional states of the sigma factor network in Geobacter sulfurreducens, revealing a unique network topology of interacting sigma factors. Analysis of the operational state of the sigma factor network shows a highly modular structure with s N being the major regulator of energy metabolism. Surprisingly, the functional state of the network during the two most divergent growth conditions is nearly static, with sigma factor binding profiles almost invariant to environmental stimuli. This first comprehensive elucidation of the interplay between different levels of the sigma factor network organization is fundamental to characterize transcriptional regulatory mechanisms in bacteria.

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The RpoS Sigma Factor in the Dissimilatory Fe(III)-Reducing Bacterium Geobacter sulfurreducens

Cited by 30 publications

References 38 publications

DNA Microarray and Proteomic Analyses of the RpoS Regulon in Geobacter sulfurreducens

DNA Microarray and Proteomic Analyses of the RpoS Regulon in Geobacter sulfurreducens

Strategies for Reducing the Start-up Operation of Microbial Electrochemical Treatments of Urban Wastewater

Characterizing the interplay between multiple levels of organization within bacterial sigma factor regulatory networks

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