scholarly journals Secreted Flavin Cofactors for Anaerobic Respiration of Fumarate and Urocanate byShewanella oneidensis: Cost and Role

2019 ◽  
Vol 85 (16) ◽  
Author(s):  
Eric D. Kees ◽  
Augustus R. Pendleton ◽  
Catarina M. Paquete ◽  
Matthew B. Arriola ◽  
Aunica L. Kane ◽  
...  
Keyword(s):  
Reductase Activity ◽  
Inorganic Compounds ◽  
Shewanella Oneidensis ◽  
Model Organism ◽  
Fitness Cost ◽  
Fumarate Reductase ◽  
Anaerobic Growth ◽  
Metal Reduction ◽  
Content Type ◽  
Dissimilatory Metal Reduction

ABSTRACTShewanella oneidensisstrain MR-1, a facultative anaerobe and model organism for dissimilatory metal reduction, uses a periplasmic flavocytochrome, FccA, both as a terminal fumarate reductase and as a periplasmic electron transfer hub for extracellular respiration of a variety of substrates. It is currently unclear how maturation of FccA and other periplasmic flavoproteins is achieved, specifically in the context of flavin cofactor loading, and the fitness cost of flavin secretion has not been quantified. We demonstrate that deletion of the inner membrane flavin adenine dinucleotide (FAD) exporter Bfe results in a 23% slower growth rate than that of the wild type during fumarate respiration and an 80 to 90% loss in fumarate reductase activity. Exogenous flavin supplementation does not restore FccA activity in a Δbfemutant unless the gene encoding the periplasmic FAD hydrolase UshA is also deleted. We demonstrate that the small Bfe-independent pool of FccA is sufficient for anaerobic growth with fumarate. Strains lacking Bfe were unable to grow using urocanate as the sole electron acceptor, which relies on the periplasmic flavoprotein UrdA. We show that periplasmic flavoprotein maturation occurs in careful balance with periplasmic FAD hydrolysis, and that the current model for periplasmic flavin cofactor loading must account for a Bfe-independent mechanism for flavin transport. Finally, we determine that the metabolic burden of flavin secretion is not significant during growth with flavin-independent anaerobic electron acceptors. Our work helps frame the physiological motivations that drove evolution of flavin secretion byShewanella.IMPORTANCEShewanellaspecies are prevalent in marine and aquatic environments, throughout stratified water columns, in mineral-rich sediments, and in association with multicellular marine and aquatic organisms. The diversity of niches shewanellae can occupy are due largely to their respiratory versatility.Shewanella oneidensisis a model organism for dissimilatory metal reduction and can respire a diverse array of organic and inorganic compounds, including dissolved and solid metal oxides. The fumarate reductase FccA is a highly abundant multifunctional periplasmic protein that acts to bridge the periplasm and temporarily store electrons in a variety of respiratory nodes, including metal, nitrate, and dimethyl sulfoxide respiration. However, maturation of this central protein, particularly flavin cofactor acquisition, is poorly understood. Here, we quantify the fitness cost of flavin secretion and describe how free flavins are acquired by FccA and a homologous periplasmic flavoprotein, UrdA.

scholarly journals Anaerobic Growth of Corynebacterium glutamicum via Mixed-Acid Fermentation

2015 ◽  
Vol 81 (21) ◽  
pp. 7496-7508 ◽  
Author(s):  
Andrea Michel ◽  
Abigail Koch-Koerfges ◽  
Karin Krumbach ◽  
Melanie Brocker ◽  
Michael Bott
Keyword(s):  
Amino Acids ◽  
Corynebacterium Glutamicum ◽  
Tricarboxylic Acid Cycle ◽  
Model Organism ◽  
Anaerobic Growth ◽  
Efficient Production ◽  
Ph Homeostasis ◽  
Anaerobic Conditions ◽  
Acid Fermentation ◽  
Content Type

ABSTRACTCorynebacterium glutamicum, a model organism in microbial biotechnology, is known to metabolize glucose under oxygen-deprived conditions tol-lactate, succinate, and acetate without significant growth. This property is exploited for efficient production of lactate and succinate. Our detailed analysis revealed that marginal growth takes place under anaerobic conditions with glucose, fructose, sucrose, or ribose as a carbon and energy source but not with gluconate, pyruvate, lactate, propionate, or acetate. Supplementation of glucose minimal medium with tryptone strongly enhanced growth up to a final optical density at 600 nm (OD600) of 12, whereas tryptone alone did not allow growth. Amino acids with a high ATP demand for biosynthesis and amino acids of the glutamate family were particularly important for growth stimulation, indicating ATP limitation and a restricted carbon flux into the oxidative tricarboxylic acid cycle toward 2-oxoglutarate. Anaerobic cultivation in a bioreactor with constant nitrogen flushing disclosed that CO2is required to achieve maximal growth and that the pH tolerance is reduced compared to that under aerobic conditions, reflecting a decreased capability for pH homeostasis. Continued growth under anaerobic conditions indicated the absence of an oxygen-requiring reaction that is essential for biomass formation. The results provide an improved understanding of the physiology ofC. glutamicumunder anaerobic conditions.

scholarly journals Staphylococcus aureusCoproporphyrinogen III Oxidase Is Required for Aerobic and Anaerobic Heme Synthesis

mSphere ◽  
2019 ◽  
Vol 4 (4) ◽  
Author(s):  
Jacob E. Choby ◽  
Eric P. Skaar
Keyword(s):  
Staphylococcus Aureus ◽  
Anaerobic Respiration ◽  
Model Organism ◽  
Anaerobic Growth ◽  
Cellular Respiration ◽  
Nitrate Respiration ◽  
Human Pathogen ◽  
Content Type ◽  
Heme Synthesis ◽  
Aerobic And Anaerobic

ABSTRACTThe virulence of the human pathogenStaphylococcus aureusis supported by many heme-dependent proteins, including key enzymes of cellular respiration. Therefore, synthesis of heme is a critical component of staphylococcal physiology.S. aureusgenerates heme via the coproporphyrin-dependent pathway, conserved across members of theFirmicutesandActinobacteria. In this work, we genetically investigate the oxidation of coproporphyrinogen to coproporphyrin in this heme synthesis pathway. The coproporphyrinogen III oxidase CgoX has previously been identified as the oxygen-dependent enzyme responsible for this conversion under aerobic conditions. However, becauseS. aureususes heme during anaerobic nitrate respiration, we hypothesized that coproporphyrin production is able to proceed in the absence of oxygen. Therefore, we tested the contribution to anaerobic heme synthesis of CgoX and two other proteins previously identified as potential oxygen-independent coproporphyrinogen dehydrogenases, NWMN_1486 and NWMN_1636. We have found that CgoX alone is responsible for aerobic and anaerobic coproporphyrin synthesis from coproporphyrinogen and is required for aerobic and anaerobic heme-dependent growth. This work provides an explanation for howS. aureusheme synthesis proceeds under both aerobic and anaerobic conditions.IMPORTANCEHeme is a critical molecule required for aerobic and anaerobic respiration by organisms across kingdoms. The human pathogenStaphylococcus aureushas served as a model organism for the study of heme synthesis and heme-dependent physiology and, like many species of the phylaFirmicutesandActinobacteria, generates heme through a coproporphyrin intermediate. A critical step in terminal heme synthesis is the production of coproporphyrin by the CgoX enzyme, which was presumed to be oxygen dependent. However,S. aureusalso requires heme during anaerobic growth; therefore, the synthesis of coproporphyrin by an oxygen-independent mechanism is required. Here, we identify CgoX as the enzyme performing the oxygen-dependent and -independent synthesis of coproporphyrin from coproporphyrinogen, resolving a key outstanding question in the coproporphyrin-dependent heme synthesis pathway.

scholarly journals The roles of CymA in support of the respiratory flexibility of Shewanella oneidensis MR-1

2012 ◽  
Vol 40 (6) ◽  
pp. 1217-1221 ◽  
Author(s):  
Sophie J. Marritt ◽  
Duncan G.G. McMillan ◽  
Liang Shi ◽  
James K. Fredrickson ◽  
John M. Zachara ◽  
...  
Keyword(s):  
Shewanella Oneidensis ◽  
Model Organism ◽  
Anaerobic Growth ◽  
Biochemical Basis ◽  
Shewanella Species ◽  
Respiratory Chains ◽  
Space Colonization ◽  
Aerobic And Anaerobic Growth ◽  
Aerobic And Anaerobic ◽  
Respiratory Electron Transport

Shewanella species are isolated from the oxic/anoxic regions of seawater and aquatic sediments where redox conditions fluctuate in time and space. Colonization of these environments is by virtue of flexible respiratory chains, many of which are notable for the ability to reduce extracellular substrates including the Fe(III) and Mn(IV) contained in oxide and phyllosilicate minerals. Shewanella oneidensis MR-1 serves as a model organism to consider the biochemical basis of this flexibility. In the present paper, we summarize the various systems that serve to branch the respiratory chain of S. oneidensis MR-1 in order that electrons from quinol oxidation can be delivered the various terminal electron acceptors able to support aerobic and anaerobic growth. This serves to highlight several unanswered questions relating to the regulation of respiratory electron transport in Shewanella and the central role(s) of the tetrahaem-containing quinol dehydrogenase CymA in that process.

scholarly journals Molecular Analysis of theIn SituGrowth Rates of Subsurface Geobacter Species

2012 ◽  
Vol 79 (5) ◽  
pp. 1646-1653 ◽  
Author(s):  
Dawn E. Holmes ◽  
Ludovic Giloteaux ◽  
Melissa Barlett ◽  
Milind A. Chavan ◽  
Jessica A. Smith ◽  
...  
Keyword(s):  
Growth Rates ◽  
Ribosomal Proteins ◽  
Specific Growth ◽  
Expression Patterns ◽  
Transcript Abundance ◽  
Metal Reduction ◽  
Content Type ◽  
Specific Growth Rates ◽  
Dissimilatory Metal Reduction

ABSTRACTMolecular tools that can provide an estimate of thein situgrowth rate ofGeobacterspecies could improve understanding of dissimilatory metal reduction in a diversity of environments. Whole-genome microarray analyses of a subsurface isolate ofGeobacter uraniireducens, grown under a variety of conditions, identified a number of genes that are differentially expressed at different specific growth rates. Expression of two genes encoding ribosomal proteins,rpsCandrplL, was further evaluated with quantitative reverse transcription-PCR (qRT-PCR) in cells with doubling times ranging from 6.56 h to 89.28 h. Transcript abundance ofrpsCcorrelated best (r2= 0.90) with specific growth rates. Therefore, expression patterns ofrpsCwere used to estimate specific growth rates ofGeobacterspecies during anin situuranium bioremediation field experiment in which acetate was added to the groundwater to promote dissimilatory metal reduction. Initially, increased availability of acetate in the groundwater resulted in higher expression ofGeobacter rpsC, and the increase in the number ofGeobactercells estimated with fluorescentin situhybridization compared well with specific growth rates estimated from levels ofin situ rpsCexpression. However, in later phases, cell number increases were substantially lower than predicted fromrpsCtranscript abundance. This change coincided with a bloom of protozoa and increased attachment ofGeobacterspecies to solid phases. These results suggest that monitoringrpsCexpression may better reflect the actual rate thatGeobacterspecies are metabolizing and growing duringin situuranium bioremediation than changes in cell abundance.

scholarly journals Phenazines Regulate Nap-Dependent Denitrification inPseudomonas aeruginosaBiofilms

2018 ◽  
Vol 200 (9) ◽  
Author(s):  
Yu-Cheng Lin ◽  
Matthew D. Sekedat ◽  
William Cole Cornell ◽  
Gustavo M. Silva ◽  
Chinweike Okegbe ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Nitrate Reductase ◽  
Electron Acceptor ◽  
Bacterial Infections ◽  
Redox State ◽  
Reductase Activity ◽  
Anaerobic Growth ◽  
Bet Hedging ◽  
Terminal Electron Acceptor ◽  
Content Type

ABSTRACTMicrobes in biofilms face the challenge of substrate limitation. In particular, oxygen often becomes limited for cells inPseudomonas aeruginosabiofilms growing in the laboratory or during host colonization. Previously we found that phenazines, antibiotics produced byP. aeruginosa, balance the intracellular redox state of cells in biofilms. Here, we show that genes involved in denitrification are induced in phenazine-null (Δphz) mutant biofilms grown under an aerobic atmosphere, even in the absence of nitrate. This finding suggests that resident cells employ a bet-hedging strategy to anticipate the potential availability of nitrate and counterbalance their highly reduced redox state. Consistent with our previous characterization of aerobically grown colonies supplemented with nitrate, we found that the pathway that is induced in Δphzmutant colonies combines the nitrate reductase activity of the periplasmic enzyme Nap with the downstream reduction of nitrite to nitrogen gas catalyzed by the enzymes Nir, Nor, and Nos. This regulatory relationship differs from the denitrification pathway that functions under anaerobic growth, with nitrate as the terminal electron acceptor, which depends on the membrane-associated nitrate reductase Nar. We identified the sequences in the promoter regions of thenapandniroperons that are required for the effects of phenazines on expression. We also show that specific phenazines have differential effects onnapgene expression. Finally, we provide evidence that individual steps of the denitrification pathway are catalyzed at different depths within aerobically grown biofilms, suggesting metabolic cross-feeding between community subpopulations.IMPORTANCEAn understanding of the unique physiology of cells in biofilms is critical to our ability to treat fungal and bacterial infections. Colony biofilms of the opportunistic pathogenPseudomonas aeruginosagrown under an aerobic atmosphere but without nitrate express a denitrification pathway that differs from that used for anaerobic growth. We report that the components of this pathway are induced by electron acceptor limitation and that they are differentially expressed over the biofilm depth. These observations suggest that (i)P. aeruginosaexhibits “bet hedging,” in that it expends energy and resources to prepare for nitrate availability when other electron acceptors are absent, and (ii) cells in distinct biofilm microniches may be able to exchange substrates to catalyze full denitrification.

scholarly journals Interplay between the Hsp90 Chaperone and the HslVU Protease To Regulate the Level of an Essential Protein in Shewanella oneidensis

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Flora Ambre Honoré ◽  
Nathanael Jean Maillot ◽  
Vincent Méjean ◽  
Olivier Genest
Keyword(s):  
Molecular Chaperones ◽  
Shewanella Oneidensis ◽  
Model Organism ◽  
Cellular Level ◽  
Growth Defect ◽  
Hsp90 Inhibition ◽  
Content Type ◽  
Hsp90 Chaperone ◽  
Bacterial Model ◽  
Client Proteins

ABSTRACT Protein synthesis, folding, and degradation are an accurately regulated process occurring in every organism and called proteostasis. This process is essential to maintain a healthy proteome since proteostasis dysregulation is responsible for devastating cellular issues. Proteostasis is controlled by a complex network of molecular chaperones and proteases. Among them, eukaryotic Hsp90, assisted by many cochaperones and the Hsp70 chaperone system, plays a major role in activating hundreds of client proteins, and Hsp90 inhibition usually leads to proteasomal degradation of these clients. In bacteria, however, the precise function of Hsp90 remains quite unclear, and only a few clients are known. Recently, we have shown that Hsp90 is essential at elevated temperature in the aquatic model bacterium Shewanella oneidensis, and we have identified a client of Hsp90, TilS, involved in tRNA modification. Here we found that two members of the proteostasis network with antagonist activities, the Hsp90 chaperone and the HslVU protease, which is considered the proteasome ancestor, together regulate the level of TilS. In particular, we show that deletion of the genes coding for the HslVU protease suppresses the growth defect of an S. oneidensis strain with hsp90 deleted, by increasing the cellular level of the essential TilS protein. These results open up new avenues for understanding how proteostasis is controlled in bacteria, and new Hsp90 clients are much needed now to confirm the interplay between Hsp90 and proteases. IMPORTANCE Maintaining a healthy proteome is essential in every living cell from bacteria to humans. For example, proteostasis (protein homeostasis) imbalance in humans leads to devastating diseases, including neurodegenerative diseases and cancers. Therefore, proteins need to be assisted from their synthesis to their native folding and ultimately to their degradation. To ensure efficient protein turnover, cells possess an intricate network of molecular chaperones and proteases for protein folding and degradation. However, these networks need to be better defined and understood. Here, using the aquatic bacterium Shewanella oneidensis as a model organism, we demonstrate interplay between two proteins with antagonist activities, the Hsp90 chaperone and the HslVU protease, to finely regulate the level of an essential client of Hsp90. Therefore, this work provides a new bacterial model to better study protein regulation and turnover, and it sheds light on how proteostasis by Hsp90 and proteases could be controlled in bacteria.

scholarly journals Shewanella decolorationis LDS1 Chromate Resistance

2019 ◽  
Vol 85 (18) ◽  
Author(s):  
Olivier N. Lemaire ◽  
Flora A. Honoré ◽  
Sébastien Tempel ◽  
Emma M. Fortier ◽  
Silke Leimkühler ◽  
...  
Keyword(s):  
Abiotic Stresses ◽  
Cold Water ◽  
Inorganic Compounds ◽  
Shewanella Oneidensis ◽  
Optimal Growth ◽  
16S Rrna Analysis ◽  
Content Type ◽  
Chromate Resistance ◽  
Toxic Dyes ◽  
Wide Range

ABSTRACT The genus Shewanella is well known for its genetic diversity, its outstanding respiratory capacity, and its high potential for bioremediation. Here, a novel strain isolated from sediments of the Indian Ocean was characterized. A 16S rRNA analysis indicated that it belongs to the species Shewanella decolorationis. It was named Shewanella decolorationis LDS1. This strain presented an unusual ability to grow efficiently at temperatures from 24°C to 40°C without apparent modifications of its metabolism, as shown by testing respiratory activities or carbon assimilation, and in a wide range of salt concentrations. Moreover, S. decolorationis LDS1 tolerates high chromate concentrations. Indeed, it was able to grow in the presence of 4 mM chromate at 28°C and 3 mM chromate at 40°C. Interestingly, whatever the temperature, when the culture reached the stationary phase, the strain reduced the chromate present in the growth medium. In addition, S. decolorationis LDS1 degrades different toxic dyes, including anthraquinone, triarylmethane, and azo dyes. Thus, compared to Shewanella oneidensis, this strain presented better capacity to cope with various abiotic stresses, particularly at high temperatures. The analysis of genome sequence preliminary data indicated that, in contrast to S. oneidensis and S. decolorationis S12, S. decolorationis LDS1 possesses the phosphorothioate modification machinery that has been described as participating in survival against various abiotic stresses by protecting DNA. We demonstrate that its heterologous production in S. oneidensis allows it to resist higher concentrations of chromate. IMPORTANCE Shewanella species have long been described as interesting microorganisms in regard to their ability to reduce many organic and inorganic compounds, including metals. However, members of the Shewanella genus are often depicted as cold-water microorganisms, although their optimal growth temperature usually ranges from 25 to 28°C under laboratory growth conditions. Shewanella decolorationis LDS1 is highly attractive, since its metabolism allows it to develop efficiently at temperatures from 24 to 40°C, conserving its ability to respire alternative substrates and to reduce toxic compounds such as chromate or toxic dyes. Our results clearly indicate that this novel strain has the potential to be a powerful tool for bioremediation and unveil one of the mechanisms involved in its chromate resistance.

scholarly journals Roles of D-Lactate Dehydrogenases in the Anaerobic Growth ofShewanella oneidensisMR-1 on Sugars

2018 ◽  
Vol 85 (3) ◽  
Author(s):  
Takuya Kasai ◽  
Yusuke Suzuki ◽  
Atsushi Kouzuma ◽  
Kazuya Watanabe
Keyword(s):  
Electron Acceptor ◽  
Deletion Mutant ◽  
Shewanella Oneidensis ◽  
Electron Acceptors ◽  
Anaerobic Growth ◽  
Receptor Protein ◽  
Acid Fermentation ◽  
Respiratory Quinone ◽  
Content Type ◽  
Electron Sink

ABSTRACTShewanella oneidensisMR-1 is a facultative anaerobe that respires using a variety of electron acceptors. Although this organism is incapable of fermentative growth in the absence of electron acceptors, its genome encodes LdhA (a putative fermentative NADH-dependentd-lactate dehydrogenase [d-LDH]) and Dld (a respiratory quinone-dependentd-LDH). However, the physiological roles of LdhA in MR-1 are unclear. Here, we examined the activity, transcriptional regulation, and traits of deletion mutants to gain insight into the roles of LdhA in the anaerobic growth of MR-1. Analyses ofd-LDH activity in MR-1 and theldhAdeletion mutant confirmed that LdhA functions as an NADH-dependentd-LDH that catalyzes the reduction of pyruvate tod-lactate.In vivoandin vitroassays revealed thatldhAexpression was positively regulated by the cyclic-AMP receptor protein, a global transcription factor that regulates anaerobic respiratory pathways in MR-1, suggesting that LdhA functions in coordination with anaerobic respiration. Notably, we found that a deletion mutant of all four NADH dehydrogenases (NDHs) in MR-1 (ΔNDH mutant) retained the ability to grow onN-acetylglucosamine under fumarate-respiring conditions, while an additional deletion ofldhAordlddeprived the ΔNDH mutant of this growth ability. These results indicate that LdhA-Dld serves as a bypass of NDH in electron transfer from NADH to quinones. Our findings suggest that the LdhA-Dld system manages intracellular redox balance by utilizingd-lactate as a temporal electron sink under electron acceptor-limited conditions.IMPORTANCENADH-dependent LDHs are conserved among diverse organisms and contribute to NAD+regeneration in lactic acid fermentation. However, this type of LDH is also present in nonfermentative bacteria, including members of the genusShewanella, while their physiological roles in these bacteria remain unknown. Here, we show that LdhA (an NADH-dependentd-LDH) works in concert with Dld (a quinone-dependentd-LDH) to transfer electrons from NADH to quinones during sugar catabolism inS. oneidensisMR-1. Our results indicate thatd-lactate acts as an intracellular electron mediator to transfer electrons from NADH to membrane quinones. In addition,d-lactate serves as a temporal electron sink when respiratory electron acceptors are not available. Our study suggests novel physiological roles ford-LDHs in providing nonfermentative bacteria with catabolic flexibility under electron acceptor-limited conditions.

scholarly journals The Response ofnorandnosContributes toStaphylococcus aureusVirulence and Metabolism

2019 ◽  
Vol 201 (9) ◽  
Author(s):  
Lacey J. Favazzo ◽  
Ann Lindley Gill ◽  
Christopher W. Farnsworth ◽  
Robert A. Mooney ◽  
Steven R. Gill
Keyword(s):  
Nitric Oxide ◽  
Staphylococcus Aureus ◽  
Reductase Activity ◽  
Wide Spectrum ◽  
Nucleotide Metabolism ◽  
Anaerobic Growth ◽  
Metabolic Adaptation ◽  
Infection Model ◽  
Polymorphonuclear Cells ◽  
Content Type

ABSTRACTStaphylococcus aureuscauses a wide spectrum of disease, with the site and severity of infection dependent on virulence traits encoded within genetically distinct clonal complexes (CCs) and bacterial responses to host innate immunity. The production of nitric oxide (NO) by activated phagocytes is a major host response to whichS. aureusmetabolically adapts through multiple strategies that are conserved in all CCs, including anS. aureusnitric oxide synthase (Nos). Previous genome analysis of CC30, a lineage associated with chronic endocardial and osteoarticular infections, revealed a putative NO reductase (Nor) not found in other CCs that potentially contributes to NO resistance and clinical outcome. Here, we demonstrate that Nor has true nitric oxide reductase activity, withnorexpression enhanced by NO stress and anaerobic growth. Furthermore, we demonstrate thatnoris regulated by MgrA and SrrAB, which modulateS. aureusvirulence and hypoxic response. Transcriptome analysis of theS. aureusUAMS-1, UAMS-1 Δnor, and UAMS-1 Δnosstrains under NO stress and anaerobic growth demonstrates that Nor contributes to nucleotide metabolism and Nos to glycolysis. We demonstrate that Nor and Nos contribute to enhanced survival in the presence of human human polymorphonuclear cells and have organ-specific seeding in a tail vein infection model. Nor contributes to abscess formation in an osteological implant model. We also demonstrate that Nor has a role inS. aureusmetabolism and virulence. The regulation overlap between Nor and Nos points to an intriguing link between regulation of intracellular NO, metabolic adaptation, and persistence in the CC30 lineage.IMPORTANCEStaphylococcus aureuscan cause disease at most body sites, and illness spans asymptomatic infection to death. The variety of clinical presentations is due to the diversity of strains, which are grouped into distinct clonal complexes (CCs) based on genetic differences. The ability ofS. aureusCC30 to cause chronic infections relies on its ability to evade the oxidative/nitrosative defenses of the immune system and survive under different environmental conditions, including differences in oxygen and nitric oxide concentrations. The significance of this work is the exploration of unique genes involved in resisting NO stress and anoxia. A better understanding of the functions that control the response ofS. aureusCC30 to NO and oxygen will guide the treatment of severe disease presentations.

scholarly journals Shewanella oneidensis MR-1 Sensory Box Protein Involved in Aerobic and Anoxic Growth

2011 ◽  
Vol 77 (13) ◽  
pp. 4647-4656 ◽  
Author(s):  
A. Sundararajan ◽  
J. Kurowski ◽  
T. Yan ◽  
D. M. Klingeman ◽  
M. P. Joachimiak ◽  
...  
Keyword(s):  
Reductase Activity ◽  
Shewanella Oneidensis ◽  
Physiological Role ◽  
Growth Conditions ◽  
Electron Acceptors ◽  
Wild Type ◽  
Lower Growth ◽  
Content Type ◽  
Reading Frame ◽  
Consumption Rates

ABSTRACTAlthough little is known of potential function for conserved signaling proteins, it is hypothesized that such proteins play important roles to coordinate cellular responses to environmental stimuli. In order to elucidate the function of a putative sensory box protein (PAS domains) inShewanella oneidensisMR-1, the physiological role of SO3389 was characterized. The predicted open reading frame (ORF) encodes a putative sensory box protein that has PAS, GGDEF, and EAL domains, and an in-frame deletion mutant was constructed (ΔSO3389) with approximately 95% of the ORF deleted. Under aerated conditions, wild-type and mutant cultures had similar growth rates, but the mutant culture had a lower growth rate under static, aerobic conditions. Oxygen consumption rates were lower for mutant cultures (1.5-fold), and wild-type cultures also maintained lower dissolved oxygen concentrations under aerated growth conditions. When transferred to anoxic conditions, the mutant did not grow with fumarate, iron(III), or dimethyl sulfoxide (DMSO) as electron acceptors. Biochemical assays demonstrated the expression of differentc-type cytochromes as well as decreased fumarate reductase activity in the mutant transferred to anoxic growth conditions. Transcriptomic studies showed the inability of the mutant to up-express and down-express genes, includingc-type cytochromes (e.g., SO4047/SO4048, SO3285/SO3286), reductases (e.g., SO0768, SO1427), and potential regulators (e.g., SO1329). The complemented strain was able to grow when transferred from aerobic to anoxic growth conditions with the tested electron acceptors. The modeled structure for the SO3389 PAS domains was highly similar to the crystal structures of FAD-binding PAS domains that are known O2/redox sensors. Based on physiological, genomic, and bioinformatic results, we suggest that the sensory box protein, SO3389, is an O2/redox sensor that is involved in optimization of aerobic growth and transitions to anoxia inS. oneidensisMR-1.

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