J23101+B0034+VHb (Vitreoscilla haemoglobin)
The BioBrick information has been updated by SCU-China 2016
This part is a hemoglobin isolated from Vitreoscilla (VHb) expressed behind a strong Anderson promoter and a strong RBS. VHb is a monomeric heme-containing protein that appears to improve the metabolic function of obligate aerobes and facultative anaerobes in low-oxygen conditions. Evidence suggests that the protein binds oxygen, then shuttles it to at least one cytochrome in the electron transport chain, improving the rate of oxidative phosphorylation and therefore ATP production even when dissolved oxygen is scarce, resulting in increased cell metabolism. This part contains a constitute promoter and RBS ready for expression.
Expressing BBa_K1321200 in pSEVA331-Bb backbone (part BBa_K1321300) in the cellulose-producing Gluconacetobacter xylinus strain igem (part BBa_K1321306; grown at 30degC 180rpm in 5ml HS-cellulase medium, in 50ml tubes for 4 days) increases biomass production almost two-fold (see Figure 1).
 http://www.ncbi.nlm.nih.gov/pubmed/2850971 - Cloning, characterisation and expression of the hemoglobin gene from Vitreoscilla in Escherichia coli.
 http://www.ncbi.nlm.nih.gov/pubmed/11478898 - Monomer-dimer equilibrium and oxygen-binding properties of ferrous Vitreoscilla hemoglobin.
 http://onlinelibrary.wiley.com/doi/10.1021/bp960071v/full - Expression of Vitreoscilla hemoglobin is superior to horse heart myoglobin or yeast flavohemoglobin for enhancing Escherichia coli growth in a microaerobic bioreactor.
 http://www.nature.com/nbt/journal/v11/n8/full/nbt0893-926.html - The production of cephalosporin C by Aecremonium chrysogenum is improved by the intracellular expression of bacterial hemoglobin.
 http://onlinelibrary.wiley.com/doi/10.1111/j.1432-1033.1994.tb19931.x/full - Intracellular expression of Vitreoscilla hemoglobin alters Escherichia coli energy metabolism under oxygen-limited conditions.
Sep. 2016, Characterization Updated by SCU-China 2016. The formation of mRFP needs oxygen molecule. So the fluoresence result remains considerations. But the OD600 data is reliable.
Vitreoscilla haemoglobin (VHb) can promote the cell growth and protein production ability. To measure the characters of Vitreoscilla haemoglobin generator constructed by iGEM14_Imperial (BBa_K1321200), we ligate mRFP generator (BBa_J04450) with VHb generator to test the protein production ability in E. coli.
In iGEM14_Imperial project, VHb is used in Gluconacetobacter xylinus strain to promote the production of cellulose. SCU-China 2016 are expected to express this gene in E. coli to promote the engineered bacteria growth ability in relatively bad condition (Shoes, for example). Except observational measurement, we did the quantitative measurement in different oxygen concentrations to test its ability.
In observational measurement, we use two E. coli BL21 strains which contain mRFP (BBa_J04450) and mRFP + VHb (K1919500) respectively to compare their growth and mRFP production by naked eyes. The result obviously shows that the colony is bigger and contains more mRFP.
In quantitative measurement, we use different oxygen concentrations (created by gas production pack) to test if VHb can really work. Because the synthesis of VHb cost energy. But if the volume of energy cost is lower than what VHb can bring, as a result, VHb makes the strain grow slower. We think oxygen concentration is an important factor. And we raise a theory called “VHb energy cost theory” in our modeling part. The result is shown in the part information page below, please visit our wiki for details http://2016.igem.org/Team:SCU-China/Model.
As the quantitative measurement results shown as follows, we conclude that in restricted environment, VHb can accelerate the growth and in early stage and it can improve the production protein. But all improvement occurs only when oxygen supply is efficient. For more details and analysis, please visit the wiki of SCU-China 2016 http://2016.igem.org/Team:SCU-China/Description.
Our project aimed to use Vitreoscilla hemoglobin (VHb) to improve the oxygen usage of the engineering bacteria, so we considered this part to get the VHb gene. However, when making alignment we found that the sequence of VHb in BBa_K1321200 was different from the original VHb both in DNA and protein. (data source: NCBI)
We transformed these constructs to E.coli.(BL21) and measured their growth curve(figure 3). From the result we can see that all the three VHb transgene bacteria grew better than the wildtype bacteria, mainly presented on the maximal bio-mass at platform, while our newly built constructs(BBa_K2833022, BBa_K2833023) showed bigger effects on the growth of the bacteria.
SHSU_China 2018 team intend to create a cellular hemoglobin (Hb) based oxygen carriers for future artificial blood design. To reach this goal, we firstly need to find Hb and then found proper carrier. We chose to use hemoglobin isolated from Vitreoscilla (VHb) as it's an ideal hp to start our project. We improved this part by creating a composite part CD63-Vhb Fusion Protein (BBa_K2794005), when this fuse genes been transfected into mammalian cells, the fusion protein will be transported to the endosome and then through inward budding and exocytosis be exported on the membrane of exosomes. In this way, Vhb located inside the exosome and it automatically transported into the exosomes.
We constructed plasmids pRK7-N-Flag-Vhb (abbreviated as PNV) and pRK7-N-Flag-CD63-Vhb plasmid (abbreviated as PNCV) to express the target protein in HEK 293T cells. SHSU_China have sequenced the plasmid and confirmed the sequence. Then SHSU_China did a series of experiments to study the function of the fusion protein
The western blotting result of whole cell lysate showed successful transfection of PNV and PNCV plasmids in HEK 293T cells. Coomassie brilliant blue staining and western blotting result of exosome content showed successful result of fusion protein band around 40 kDa. TEM imaging result of sample showed that exogenous protein doesn’t effect the shape or the concentration of exosomes. COD result compared to normal exosomes showd that the fusion protein containing heme group that could increase the chemical demand of exosomes and thus proving the function of Vhb is not disturbed. Also, color difference can be seen between normal and fusion-protein containing exosomes.
Sequence and Features
- 10COMPATIBLE WITH RFC
- 12Illegal NheI site found at 7
Illegal NheI site found at 30
- 21Illegal BglII site found at 477
- 23COMPATIBLE WITH RFC
- 25COMPATIBLE WITH RFC
- 1000COMPATIBLE WITH RFC
IMPROVEMENT REFERENCE: BNU-China 2018
The part was linked with a periplasm-targeted signal peptide TorA to enhance its function of growth promotion. The new part is : BBa_K2717013(Group: iGEM18_BNU-China), Designed by: Chenyu Liu.
IMPROVEMENT REFERENCE: SHSU_China 2018
The part was linked with a membrane anchoring protein CD63 and when this fusion gene been transfected into cells, VHb could located inside the exosome and it automatically transported into the exosomes. The new part is : BBa_K2794005(Group: iGEM18 SHSU_China), Designed by: Luo Yan.