Characterization of the oxygen-dependent promoter of the Vitreoscilla hemoglobin gene in Escherichia coli

Khosla, Chaitan; Bailey, James E.

doi:10.1128/jb.171.11.5995-6004.1989

Cited by 98 publications

(67 citation statements)

References 43 publications

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“…After the cloning of the VHb gene ( vgb ), VHb was expressed in a number of heterologous bacterial and eukaryotic hosts, where, in general, it was associated with enhanced growth. In its native host, as well as several of the heterologous hosts, VHb production is induced under conditions of low oxygen or hypoxic conditions [Boerman and Webster, 1982;Dikshit et al, 1990;Joshi and Dikshit, 1994;Khosla and Bailey, 1989;Tsai et al, 1995b;Yang et al, 2005]. Transformation of Escherichia coli with vgb was particularly simple because of the extensive knowledge of the genetics, molecular biology, and biochemistry in this organism.…”

Section: Introductionmentioning

confidence: 99%

Role of Hemoglobin in Improving Biodegradation of Aromatic Contaminants under Hypoxic Conditions

2008

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Genetic engineering of bacteria using the Vitreoscilla (bacterial) hemoglobin gene has been used to enhance bioremediation of several compounds which are models for, or are themselves, toxic chemicals which may contaminate soil and water. Initial experiments, done mostly in shake flasks, with Escherichia coli, Burkholderia sp. DNT and Pseudomonas aeruginosa demonstrated that expression of Vitreoscilla hemoglobin in heterologous hosts can enhance biodegradation of several aromatic compounds as well as an organophosphorus compound. These studies concentrated for the most part on enhancement of endogenous catabolic capabilities of the hosts; the presence of vgb/VHb enhanced both growth and biodegradation. The initial studies were followed by experiments in systems which more closely approximated conditions that would exist in field applications. These included soil columns, continuous flow reactors and membrane bioreactors. The latter work also enabled calculation of the effects of the presence of vgb/VHb on kinetic parameters such as growth rate, substrate and oxygen utilization rate, and degradation rate of pollutants, etc. Although not always the case, for the most part, and particularly in bioreactors, the advantages due to vgb/VHb were greater under conditions of limited aeration or hypoxic conditions.

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Section: Introductionmentioning

confidence: 99%

Role of Hemoglobin in Improving Biodegradation of Aromatic Contaminants under Hypoxic Conditions

2008

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“…Transcription of the hemoglobin from the aerobic bacterium Vitreoscilla is elevated under oxygen-limiting conditions (6,7). Heterologous overexpression of the Vitreoscilla globin allows growth to higher cell densities in Escherichia coli and nearly doubles the growth rate of transgenic tobacco, suggesting an ability to increase the availability of intracellular oxygen (8,9).…”

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Role for the Salmonella Flavohemoglobin in Protection from Nitric Oxide

Crawford

Goldberg

1998

Journal of Biological Chemistry

164

146

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Hemoglobin homologs are being identified in an expanding number of unicellular prokaryotic and eukaryotic organisms. Many of these hemoglobins are twodomain proteins that possess a flavin-containing reductase in their C terminus. Determination of a function for these flavohemoglobins has been elusive. A Salmonella typhimurium strain harboring a deletion in the flavohemoglobin gene shows no difference in growth under oxidative stress conditions but displays an increased sensitivity to acidified nitrite and S-nitrosothiols, both of which produce nitric oxide. The effect is seen aerobically or anaerobically, indicating that oxygen is not required for flavohemoglobin function. These results suggest a role for the bacterial flavohemoglobins that is independent of oxygen metabolism and provide evidence for a bacterial route of protection from nitric oxide that is distinct from oxidative stress responses.

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“…The evolutionary and functional significance of VHb in existing as single-domain hemoglobin and its implication in Vitreoscilla cellular metabolism remains unclear. In the strictly aerobic bacterium Vitreoscilla sp., expression of the vgb gene is strongly induced by a decrease in oxygen level (8,9,26). Extensive biochemical and genetic studies on VHb have suggested that it facilitates oxygen delivery to the respiratory apparatus of its host (45) and thus enhances its growth metabolism (25,27) or that it may act as an alternative terminal oxidase itself (10).…”

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Chimeric Vitreoscilla Hemoglobin (VHb) Carrying a Flavoreductase Domain Relieves Nitrosative Stress in Escherichia coli : New Insight into the Functional Role of VHb

Kaur

Pathania

Sharma

et al. 2002

Appl Environ Microbiol

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Dimeric hemoglobin (VHb) from the bacterium Vitreoscilla sp. strain C1 displays 30 to 53% sequence identity with the heme-binding domain of flavohemoglobins (flavoHbs) and exhibits the presence of potential sites for the interaction with its FAD/NADH reductase partner. The intersubunit contact region of VHb indicates a small interface between two monomers of the homodimer, suggesting that the VHb dimers may dissociate easily. Gel filtration chromatography of VHb exhibited a 25 to 30% monomeric population of VHb, at a low protein concentration (0.05 mg/ml), whereas dimeric VHb remained dominant at a high protein concentration (10 mg/ml). The structural characteristics of VHb suggest that the flavoreductase can also associate and interact with VHb in a manner analogous to flavoHbs and could yield a flavo-VHb complex. To unravel the functional relevance of the VHb-reductase association, the reductase domain of flavoHb from Ralstonia eutropha (formerly Alcaligenes eutrophus) was genetically engineered to generate a VHb-reductase chimera (VHb-R). The physiological implications of VHb and VHb-R were studied in an hmp mutant of Escherichia coli, incapable of producing any flavoHb. Cellular respiration the of the hmp mutant was instantaneously inhibited in the presence of 10 M nitric oxide (NO) but remained insensitive to NO inhibition when these cells produced VHb-R. In addition, E. coli overproducing VHb-R exhibited NO consumption activity that was two to three times slower in cells overexpressing only VHb and totally undetectable in the control cells. A purified preparation of VHb-R exhibited a three-to fourfold-higher NADH-dependent NO uptake activity than that of VHb alone. Overproduction of VHb-R in the hmp mutant of E. coli conferred relief from the toxicity of sodium nitroprusside, whereas VHb alone provided only partial benefit under similar condition, suggesting that the association of VHb with reductase improves its capability to relieve the deleterious effect of nitrosative stress. Based on these results, it has been proposed that the unique structural features of VHb may allow it to acquire two functional states in vivo, namely, a single-domain homodimer that may participate in facilitated oxygen transfer or a two-domain heterodimer in association with its partner reductase that may be involved in modulating the cellular response under different environmental conditions. Due to this inherent structural flexibility, it may perform multiple functions in the cellular metabolism of its host. Separation of the oxidoreductase domain from VHb may thus provide a physiological advantage to its host.Flavohemoglobins (flavoHbs), resulting from the integration of an N-terminal heme-binding domain with a flavin-binding reductase domain, have been identified in a number of bacteria and yeast (4,5,12,20,38,43). These proteins have been shown to play an important role in the metabolism of oxygen and nitrogenous compounds (3,6,29,35,36). In addition to their putative role in oxygen sensing, diffusion, and utilization, flavo...

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Characterization of the oxygen-dependent promoter of the Vitreoscilla hemoglobin gene in Escherichia coli

Cited by 98 publications

References 43 publications

Role of Hemoglobin in Improving Biodegradation of Aromatic Contaminants under Hypoxic Conditions

Role of Hemoglobin in Improving Biodegradation of Aromatic Contaminants under Hypoxic Conditions

Role for the Salmonella Flavohemoglobin in Protection from Nitric Oxide

Chimeric Vitreoscilla Hemoglobin (VHb) Carrying a Flavoreductase Domain Relieves Nitrosative Stress in Escherichia coli : New Insight into the Functional Role of VHb

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