Vitreoscilla

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 1668 Experts worldwide ranked by ideXlab platform

Dale A. Webster - One of the best experts on this subject based on the ideXlab platform.

  • Vitreoscilla hemoglobin aids respiration under hypoxic conditions in its native host.
    Microbiological research, 2007
    Co-Authors: Pao-yu Chi, Dale A. Webster, Benjamin C. Stark
    Abstract:

    Summary When Vitreoscilla were grown in medium containing 60 mM sodium nitrite under both normal and limited aeration conditions, the levels of Vitreoscilla hemoglobin (VHb) were decreased by greater than 90%, while the levels of the terminal respiratory oxidase, cytochrome bo , were increased 350% under normal aeration and 7–23% under limited aeration. Cytochrome function, as measured by both NADH and ubiquinol oxidases for cells grown under both conditions, increased in parallel (by 150–222% and 8–56%, respectively, for the two activities). Nitrite in the medium inhibited Vitreoscilla growth at both normal and limited aeration. The inhibition of VHb at 60 mM nitrite decreased whole cell respiration to the greatest degree in stationary phase for growth in limited aeration conditions, which was the most oxygen poor condition tested. These results are consistent with the originally proposed role for VHb, as an aid to respiration under hypoxic conditions.

  • Role of Asp544 in subunit I for Na(+) pumping by Vitreoscilla cytochrome bo.
    Biochemical and Biophysical Research Communications, 2006
    Co-Authors: Yeon T. Chung, Benjamin C. Stark, Dale A. Webster
    Abstract:

    Abstract The conserved Glu540 in subunit I of Escherichia coli cytochrome bo (a H+ pump) is replaced by Asp544 in the Vitreoscilla enzyme (a Na+ pump). Site-directed mutagenesis of the Vitreoscilla cytochrome bo operon changed this Asp to Glu, and both wild type and mutant cyo’s were transformed into E. coli strain GV100, which lacks cytochrome bo. Compared to the wild type transformant the Asp544Glu transformant had decreased ability to pump Na+ as well as decreased stimulation in respiratory activity in the presence of Na+. Preliminary experiments indicated that this mutant also had increased ability to pump protons, suggesting that this single change may provide cation pumping specificity in this group of enzymes.

  • Evidence that Na+-pumping occurs through the D-channel in Vitreoscilla cytochrome bo.
    Biochemical and biophysical research communications, 2005
    Co-Authors: Seong K. Kim, Benjamin C. Stark, Dale A. Webster
    Abstract:

    Abstract The operon ( cyo ) encoding the Na + -pumping respiratory terminal oxidase (cytochrome bo ) of the bacterium Vitreoscilla was transformed into Escherichia coli GV100, a deletion mutant of cytochrome bo . This was done for the wild type operon and five mutants in three conserved Cyo subunit I amino acids known to be crucial for H + transport in the E. coli enzyme, one near the nuclear center, one in the K-channel, and one in the D-channel. CO-binding, NADH and ubiquinol oxidase, and Na + -pumping activities were all substantially inhibited by each mutation. The wild type Vitreoscilla cytochrome bo can pump Na + against a concentration gradient, resulting in a transmembrane concentration differential of 2–3 orders of magnitude. It is proposed that Vitreoscilla cytochrome bo pumps four Na + through the D-channel to the exterior and transports four H + through the K-channel for the reduction of each O 2 .

  • Improvement of bioremediation by Pseudomonas and Burkholderia by mutants of the Vitreoscilla hemoglobin gene (vgb) integrated into their chromosomes
    Journal of Industrial Microbiology and Biotechnology, 2005
    Co-Authors: Yongsoon Kim, Dale A. Webster, Benjamin C. Stark
    Abstract:

    Using genetic engineering, the Vitreoscilla (bacterial) hemoglobin gene ( vgb ) was integrated stably into the chromosomes of Pseudomonas aeruginosa and Burkholderia sp. strain DNT. This was done for both wild type vgb and two site-directed mutants of vgb that produce Vitreoscilla hemoglobin (VHb) with lowered oxygen affinities; in all cases functional VHb was expressed. Similar to previous results, the wild type VHb improved growth for both species and degradation of 2,4-dinitrotoluene ( Burkholderia sp.) or benzoic acid ( P. aeruginosa ) under both normal and low aeration conditions. Both mutant vgb s enhanced these parameters compared to wild type vgb , and the improvement was seen in both species. The enhancements were generally greater at low aeration than at normal aeration. The results demonstrate the possibility that the positive effects provided by VHb may be augmented by protein engineering.

  • ArcA works with Fnr as a positive regulator of Vitreoscilla (bacterial) hemoglobin gene expression in Escherichia coli
    Microbiological research, 2005
    Co-Authors: Jianguo Yang, Dale A. Webster, Benjamin C. Stark
    Abstract:

    Summary Low oxygen induction of the bacterial (Vitreoscilla) hemoglobin gene (vgb) by the Arc system was investigated, as the presumptive vgb Crp site was found to have 73% identity to the Escherichia coli consensus ArcA site. The role of ArcA by itself and with Fnr was examined in E. coli using the wild type vgb promoter and promoter mutants affecting the Fnr and Crp (presumptive ArcA) sites and E. coli strains with all combinations of fnr+/fnr−, arcA+/arcA− genotypes. High-level transcription required both ArcA and Fnr systems to be functional; low oxygen induction required at least one of ArcA and Fnr to be intact. Levels of Vitreoscilla hemoglobin protein (VHb) followed the same trends as seen with mRNA, although the relative decreases in the mutants relative to wild type were less than with transcription. Growth of cells was stimulated by VHb, generally to a greater extent as VHb levels increased.

Benjamin C. Stark - One of the best experts on this subject based on the ideXlab platform.

  • Bioethanol production from whey powder by immobilized E. coli expressing Vitreoscilla hemoglobin: optimization of sugar concentration and inoculum size
    Biofuels, 2019
    Co-Authors: Taner Sar, Benjamin C. Stark, Meltem Yesilcimen Akbas
    Abstract:

    A combined Vitreoscilla hemoglobin/immobilization system was evaluated for ethanol production using whey powder as a carbon source and ethanologenic E. coli strain FBR5 and its Vitreoscilla hemoglo...

  • Bioethanol production from whey powder by immobilized E. coli expressing Vitreoscilla hemoglobin: optimization of sugar concentration and inoculum size
    2019
    Co-Authors: Taner Sar, Benjamin C. Stark, Meltem Yesilcimen Akbas
    Abstract:

    A combined Vitreoscilla hemoglobin/immobilization system was evaluated for ethanol production using whey powder as a carbon source and ethanologenic E. coli strain FBR5 and its Vitreoscilla hemoglobin (VHb) expressing derivative strain, TS3. The effects of varying the inoculation concentration (5, 10, 20 or 30%) of alginate beads containing cells of either strain, and the lactose levels (8–15%) of whey powder media (WP8-WP15), were studied. Ethanol production was enhanced in strain TS3 compared to strain FBR5 for all combinations of inoculation size and medium lactose concentration. This enhancement increased from 41% to 83% with an 8–15% increase in lactose concentration. The maximum amount of ethanol, 4.64% (v/v) with 99% fermentation efficiency, was produced after growth for 72 h by immobilized strain TS3, using 10% bead inoculation and medium containing 8% lactose.

  • Complete Genome Sequence of Vitreoscilla sp. Strain C1, Source of the First Bacterial Hemoglobin.
    Microbiology resource announcements, 2018
    Co-Authors: Iva A. Veseli, Benjamin C. Stark, Anne Caroline Mascarenhas Dos Santos, Oscar Juárez, Jean-françois Pombert
    Abstract:

    ABSTRACT Vitreoscilla sp. strain C1 is of historical importance as the source of the first prokaryotic hemoglobin identified. Vitreoscilla spp. rely on their hemoglobin and cytochrome oxidase to grow in microaerobic environments despite their aerobic nature. To help characterize this historically relevant strain, we sequenced the complete Vitreoscilla sp. strain C1 genome.

  • enhancement of ethanol production from potato processing wastewater by engineering escherichia coli using Vitreoscilla haemoglobin
    Letters in Applied Microbiology, 2012
    Co-Authors: K Abanoz, Benjamin C. Stark, Meltem Yesilcimen Akbas
    Abstract:

    Ethanologenic Escherichia coli strain FBR5 was transformed with the Vitreoscilla haemoglobin (VHb) gene (vgb) in two constructs (resulting in strains TS3 and TS4). Strains FBR5, TS3 and TS4 were grown at two scales in LB medium supplemented with potato-processing wastewater hydrolysate. Aeration was varied by changes in the medium volume to flask volume ratio. Parameters measured included culture pH, cell growth, VHb levels and ethanol production. VHb expression in strains TS3 and TS4 was consistently correlated with increases in ethanol production (5–18%) under conditions of low aeration, but rarely did this occur with normal aeration. The increase in ethanol yields under low aeration conditions was the result of enhancement of ethanol produced per unit of biomass rather than enhancement of growth. ‘VHb technology’ may be a useful adjunct in the production of biofuels from food-processing wastewater. Significance and Impact of Study Genetic engineering using Vitreoscilla haemoglobin (VHb) has been shown previously to increase ethanol production by Escherichia coli from fermentation of the sugars in corn fibre hydrolysate. The study reported here demonstrates a similar VHb enhancement of ethanol production by fermentation of the glucose from potato waste water hydrolysate and thus extends the list of sugar containing waste products from which ethanol production may be enhanced by this strategy.

  • THE BIOCHEMISTRY OF Vitreoscilla HEMOGLOBIN
    Computational and structural biotechnology journal, 2012
    Co-Authors: Benjamin C. Stark, Kanak L. Dikshit, Krishna R. Pagilla
    Abstract:

    The hemoglobin (VHb) from Vitreoscilla was the first bacterial hemoglobin discovered. Its structure and function have been extensively investigated, and engineering of a wide variety of heterologous organisms to express VHb has been performed to increase their growth and productivity. This strategy has shown promise in applications as far-ranging as the production of antibiotics and petrochemical replacements by microorganisms to increasing stress tolerance in plants. These applications of “VHb technology” have generally been of the “black box” variety, wherein the endpoint studied is an increase in the levels of a certain product or improved growth and survival. Their eventual optimization, however, will require a thorough understanding of the various functions and activities of VHb, and how VHb expression ripples to affect metabolism more generally. Here we review the current knowledge of these topics. VHb's functions all involve oxygen binding (and often delivery) in one way or another. Several biochemical and structure-function studies have provided an insight into the molecular details of this binding and delivery. VHb activities are varied. They include supply of oxygen to oxygenases and the respiratory chain, particularly under low oxygen conditions; oxygen sensing and modulation of transcription factor activity; and detoxification of NO, and seem to require interactions of VHb with “partner proteins”. VHb expression affects the levels of ATP and NADH, although not enormously. VHb expression may affect the level of many compounds of intermediary metabolism, and, apparently, alters the levels of expression of many genes. Thus, the metabolic changes in organisms engineered to express VHb are likely to be numerous and complicated.

Kanak L. Dikshit - One of the best experts on this subject based on the ideXlab platform.

  • THE BIOCHEMISTRY OF Vitreoscilla HEMOGLOBIN
    Computational and structural biotechnology journal, 2012
    Co-Authors: Benjamin C. Stark, Kanak L. Dikshit, Krishna R. Pagilla
    Abstract:

    The hemoglobin (VHb) from Vitreoscilla was the first bacterial hemoglobin discovered. Its structure and function have been extensively investigated, and engineering of a wide variety of heterologous organisms to express VHb has been performed to increase their growth and productivity. This strategy has shown promise in applications as far-ranging as the production of antibiotics and petrochemical replacements by microorganisms to increasing stress tolerance in plants. These applications of “VHb technology” have generally been of the “black box” variety, wherein the endpoint studied is an increase in the levels of a certain product or improved growth and survival. Their eventual optimization, however, will require a thorough understanding of the various functions and activities of VHb, and how VHb expression ripples to affect metabolism more generally. Here we review the current knowledge of these topics. VHb's functions all involve oxygen binding (and often delivery) in one way or another. Several biochemical and structure-function studies have provided an insight into the molecular details of this binding and delivery. VHb activities are varied. They include supply of oxygen to oxygenases and the respiratory chain, particularly under low oxygen conditions; oxygen sensing and modulation of transcription factor activity; and detoxification of NO, and seem to require interactions of VHb with “partner proteins”. VHb expression affects the levels of ATP and NADH, although not enormously. VHb expression may affect the level of many compounds of intermediary metabolism, and, apparently, alters the levels of expression of many genes. Thus, the metabolic changes in organisms engineered to express VHb are likely to be numerous and complicated.

  • Vitreoscilla hemoglobin. Intracellular localization and binding to membranes.
    The Journal of biological chemistry, 2001
    Co-Authors: Ramandeep, Kyung Jin Kim, Benjamin C. Stark, Kanak L. Dikshit, Kwang-woo Hwang, Manoj Raje, Dale A. Webster
    Abstract:

    The obligate aerobic bacterium, Vitreoscilla, synthesizes elevated quantities of a homodimeric hemoglobin (VHb) under hypoxic growth conditions. Expression of VHb in heterologous hosts often enhances growth and product formation. A role in facilitating oxygen transfer to the respiratory membranes is one explanation of its cellular function. Immunogold labeling of VHb in both Vitreoscilla and recombinant Escherichia coli bearing the VHb gene clearly indicated that VHb has a cytoplasmic (not periplasmic) localization and is concentrated near the periphery of the cytosolic face of the cell membrane. OmpA signal-peptide VHb fusions were transported into the periplasm in E. coli, but this did not confer any additional growth advantage. The interaction of VHb with respiratory membranes was also studied. The K(d) values for the binding of VHb to Vitreoscilla and E. coli cell membranes were approximately 5-6 microm, a 4-8-fold higher affinity than those of horse myoglobin and hemoglobin for these same membranes. VHb stimulated the ubiquinol-1 oxidase activity of inverted Vitreoscilla membranes by 68%. The inclusion of Vitreoscilla cytochrome bo in proteoliposomes led to 2.4- and 6-fold increases in VHb binding affinity and binding site number, respectively, relative to control liposomes, suggesting a direct interaction between VHb and cytochrome bo.

  • Hemoglobin Biosynthesis in Vitreoscilla stercoraria DW: Cloning, Expression, and Characterization of a New Homolog of a Bacterial Globin Gene
    Applied and environmental microbiology, 1998
    Co-Authors: Meenal Joshi, Shekhar C. Mande, Kanak L. Dikshit
    Abstract:

    In the strictly aerobic, gram-negative bacterium Vitreoscilla strain C1, oxygen-limited growth conditions create a more than 50-fold increase in the expression of a homodimeric heme protein which was recognized as the first bacterial hemoglobin (Hb). The recently determined crystal structure of Vitreoscilla Hb has indicated that the heme pocket of microbial globins differs from that of eukaryotic Hbs. In an attempt to understand the diverse functions of Hb-like proteins in prokaryotes, we have cloned and characterized the gene (vgb) encoding an Hb-like protein from another strain of Vitreoscilla, V. stercoraria DW. Several silent changes were observed within the coding region of the V. stercoraria vgb gene. Apart from that, V. stercoraria Hb exhibited interesting differences between the A and E helices. Compared to its Hb counterpart from Vitreoscilla strain C1, the purified preparation of V. stercoraria Hb displays a slower autooxidation rate. The differences between Vitreoscilla Hb and V. stercoraria Hb were mapped onto the three-dimensional structure of Vitreoscilla Hb, which indicated that the four changes, namely, Ile7Val, Ile9Thr, Ile10Ser, and Leu62Val, present within the V. stercoraria Hb fall in the region where the A and E helices contact each other. Therefore, alteration in the relative orientation of the A and E helices and the corresponding conformational change in the heme binding pocket of V. stercoraria Hb can be correlated to its slower autooxidation rate. In sharp contrast to the oxygen-regulated biosynthesis of Hb in Vitreoscilla strain C1, production of Hb in V. stercoraria has been found to be low and independent of oxygen control, which is supported by the absence of a fumarate and nitrate reductase regulator box within the V. stercoraria vgb promoter region. Thus, the regulation mechanisms of the Hb-encoding gene appear to be quite different in the two closely related species of Vitreoscilla. The relatively slower autooxidation rate of V. stercoraria Hb, lack of oxygen sensitivity, and constitutive production of Hb suggest that it may have some other function(s) in the cellular physiology of V. stercoraria DW, together with facilitated oxygen transport, predicted for earlier reported Vitreoscilla Hb.

  • OXYGEN DEPENDENT REGULATION OF Vitreoscilla GLOBIN GENE : EVIDENCE FOR POSITIVE REGULATION BY FNR
    Biochemical and biophysical research communications, 1994
    Co-Authors: Meenal Joshi, Kanak L. Dikshit
    Abstract:

    Vitreoscilla globin (vgb) gene, encoding for Vitreoscilla haemoglobin (VtHb) has been cloned and functionally expressed in heterologous bacterial hosts. Analysis of vgb gene expression and the study on vgb-xylE transcriptional fusion revealed that vgb promoter is preferentially activated in response to oxygen limitation in Vitreoscilla and other heterologous bacterial hosts. Microaerobic mode of induction in various hosts, provided evidence for a common regulatory factor involved in activation of vgb promoter under hypoxic condition. Primary structure analysis of vgb upstream regulatory region indicated the presence of a possible binding site for the transcriptional activator, FNR. Further, the E.coli mutant lacking fnr gene product was not able to activate vgb promoter under microaerobic condition, suggesting the involvement of FNR or FNR-like proteins in modulating its activity. The possibility of a second level of control by CRP is also indicated. Oxygen responsive nature and regulatory characteristics of vgb promoter offers a novel system for the expression of gene in heterologous bacterial hosts in an oxygen dependent manner.

  • The bacterial hemoglobin from Vitreoscilla can support the aerobic growth of Escherichia coli lacking terminal oxidases
    Archives of biochemistry and biophysics, 1992
    Co-Authors: Rajendra P. Dikshit, Kanak L. Dikshit, Yixiang Liu, Dale A. Webster
    Abstract:

    Two Escherichia coli mutants that lack both cytochrome o and d terminal oxidases are able to grow with glucose as the carbon source but not with the aerobic substrates succinate or lactate. One of these, GV101, is a deletion mutant of cytochrome o and a point mutation of cytochrome d. The other, GK100, is a total deletion mutant of all the genes for both cytochromes. When these mutants were transformed with a plasmid containing the gene for the bacterial hemoglobin from Vitreoscilla, they were capable of growth in the presence of succinate or lactate and showed aerobic respiration in the presence of these substrates, unlike the parent strains. Cells transformed with a plasmid containing the gene for the hemoglobin but lacking the native promoter did not express the hemoglobin and did not respire. Membrane vesicles prepared from the cells consumed oxygen in the presence of succinate. This succinate-supported respiration decreased with successive washings of the vesicles but was restored by adding E. coli cytosol containing the hemoglobin or by adding the hemoglobin purified from Vitreoscilla. This respiration was inhibited by cyanide.

Pierreedouard Fournier - One of the best experts on this subject based on the ideXlab platform.

S. Ndongo - One of the best experts on this subject based on the ideXlab platform.

Related terms

Vitreoscilla - 15 days free trial to Access Experts & Abstracts