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Biotechnology for renewable energy and environmental protection
Kornél KOVÁCS Dept. Biotechnology, Univ. Szeged Institute of Biophysics, BRC
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BIOHYDROGEN
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Need for alternative energy
Fossil energy shortage Oil and natural gas: <30 years Coal: greenhouse effect Fossil energy Coal Oil and natural gas yr
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Nukleáris energia: maghasadás / magfúzió
Nuclear energy: nuclear fission / fusion Coal Wood Natural gas Oil Fission Solar yr
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HYDROGEN METABOLISM Archeae, Eubacteria, Cyanobacteri, Algaea Enzymes
Nitrogenase (N2 + 4H2 2 NH4+) Hydrogenase (2H+ + 2e- H2) Fe-only (e.g. Clostridium) [NiFe] No metal (methanogen)
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Solar energy numbers Energy utilization today 1
Known fossil reserves Coal ~ 80 Oil, natural gas ~ 20 Solar energy on Earth 1 hour of Solar 1 year of use today
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Several sources, one carrier: H2
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BIOLOGICAL H2 PRODUCTION
Hydrogenase Photosynthesis e- + H2O O2 2e- 2 H+ H2 2H+ Biomass e- 2 H+ H2
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HYDROGEN METABOLISM Archeae, Eubacteria, Cyanobacteria, Algaea Enzymes
Nitrogenase (N2 + 4H2 2 NH4+) Hydrogenase (2H+ + 2e- H2) Fe-only (e.g. Clostridium) [NiFe] No metal (methanogen)
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MICROORGANISMS Thiocapsa roseopersicina
Thermococcus litoralis, T. sibiricus Methylococcus capsulatus (Bath) Methylocaldum szegediense
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HYDROGENASES Redox metalloenzymes Conserved sequence and structure
[NiFe] + n [Fe4Sx] Conserved sequence and structure Very sensitive heat, oxygen, redox potential Biotechnology needs stable catalyst !!! H2 evolution biohydrogen H2 uptake fuel cell
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Hydrogenase activity assay
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Biohydrogen utilization
evolution reduction ENERGY hydrogenase H2 uptake oxidation e- REDUCINGAGENT Biogas, denitrification, etc.
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[NiFe] hydrogenases Heterodimer [NiFe] + CO/2CN 3 x [Fe4S4]
64kDa + 34kDa [NiFe] + CO/2CN on large subunit 3 x [Fe4S4] on small subunit 14-15 Angstrom apart
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Thiocapsa roseopersicina BBS
- phototrophic purple sulfur bacterium - max. growth temperature 30°C - anaerobic growth - isolated from cold sea water - [NiFe] hydrogenases H2 2H+ + 2e-
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T. roseopersicina stable Hase
pure enzyme whole cell Heat Oxygen Proteases Specific activity Temperature
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LOCATION: Hyd / Hup / Hox
Xred: GASH ? 2H+ PS ATP ? H2 HydL 2H+ 2e- Xox Xred ADP+Pi ATP HydS Isp1 Isp2 2e- + 2H+ N2ase 2H+ ATP ADP+Pi NH4+ 2e- N2 HupL HupS HupC 2H+ HoxH HoxY HoxU HoxF NAD+ NADH+H+ GASH:glutathion amide
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Hydrogenase inventory
Reaction catalysed: H2 2H+ + 2e- Stable Hase in the membrane: heat, protease hydS hydL isp2 isp1 hupS hupL hupC hupD hupH hup I hupR Unstable Hase in the membrane: why unstable? Hase in the cytoplasm: hydrogen evolution? hoxF hoxH hoxY huxU Hydrogen sensing Hase: oxygen, CO hupT hupU hupV Thiocapsa roseopersicina
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Interposon mutagenesis of the hydrogenase
structural genes sacB hydS isp1 isp2 hydL Sm strain:GB11 hupS hupL hupC hupD hupH hupI ORF-1 hupR sacB Gm strain: GB1121
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GB1121: The first good H2 producing strain by hydrogenase enzyme
140 120 100 80 In vivo H2 production (%) 60 40 20 wild type double mutant HypF-mutant strains Non nitrogen-fixing conditions -there is at least one additional hydrogenase in Thiocapsa roseopersicina !
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? In the GB1121 strain the H2 is produced by hydrogenase citoplasm
PS ATP 2H+ H2 2H+ HydL HupL HydS HupS Isp1 2e- HupC Isp2 ADP+Pi ATP ADP+Pi NH4+ ATP 2e- 2e- + 2H+ ? N2 Xred Xox H2 N2ase Xred: GASH ? H2 citoplasm GASH: glutathion amide 2H+ soluble hydrogenase
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3D MODELLING Only in HydSL Only in HupSL-ben Shared
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Looking for stabilizing elements
Random mutagenesis PCR errors (labor evolution) Chimeric enzymes DNS shuffling Site specific mutagenesis
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Accessory genes R. capsulatus hup: W X T U V S L C D FG H J K R
hyp: F A B D E
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Applied gene transfer systems
E. coli : donor T. roseopersicina: recipient mob Tn5 RP4 tra Site directed mutagenesis Normal conjugation Transposon Complementation
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Screening H2 H2 + 2MV2+ 2MV+ + 2H+ Hydrogenase
Heat treatment (optional) methyl-viologen 75 oC, 1-3h, air H2 H2 + 2MV2+ 2MV+ + 2H+ Hydrogenase
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Mutagenesis studies Hase maturation = complex process Investigation:
- mutation = loss of function - correction via complementation Wild Mutant hypF hupK hypC1 hypD hypE hypC2 hydD
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polypeptide (HupL/HydL)
Maturation / Assembly Large subunit polypeptide (HupL/HydL) Small subunit polypeptide (HupS/HydS) folding HypC Fex-Sx incorporation Fex-Sx cluster synthesis HypE, Fe? HypF (CO, CN) HypB (Ni) HypD HypD + HypC C-terminal peptidase (HupD/HydD) Membrane transport Tat-mechanisms active enzyme
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Role of the HypC protein in the maturation process
Small subunit C Cys Large subunit HypC
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Role of the HypF auxiliary protein
Cys HypC N C Cys Large subunit N Small subunit CN- CO HypF CN- (+HypE)
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Role of the HypB and HypD proteins
GTP GDP + Pi Ni HypB Cys HypC N C Cys Large subunit N Small subunit CO CN Fe HypD
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In vivo hydorgen production (%)
In vivo H2 production 700 600 500 400 In vivo hydorgen production (%) 300 200 100 wild type double mutant hypF- Nitrogen-fixing conditions
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polypeptide (HupL/HydL)
Maturation / Assembly Large subunit polypeptide (HupL/HydL) Small subunit polypeptide (HupS/HydS) folding HypC Fex-Sx incorporation Fex-Sx cluster synthesis HypE, Fe? HypF (CO, CN) HypB (Ni) HypD HypD + HypC C-terminal peptidase (HupD/HydD) Membrane transport Tat-mechanisms active enzyme
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HypF- = Hyd- / Hup- / Hox-
N2áz 2e- + 2H+ 2H+ ATP ADP+Pi NH4+ 2e- N2 HupL HupS HupC H2 HydL Xred HydS Isp1 Isp2 Xred: GASH ? PS ? GASH:glutation amide Nitrogenase Hydrogen is produced by the nitrogenase complex
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Effect of the hupK deletion on the Hyd uptake activity
100 100 80 activity % 60 40 20 4,7 HupK- mutant wild type -measured on membrane fraction at 55 oC
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Accessory genes R. capsulatus T. roseopersicina hup:
W X T U V S L C D FG H J K R hyp: F A B D E T. roseopersicina (instabil) : struktural genes (hupS, hydS, hupL, hydL) : accessory genes in R.capsulatus : accessory genes in T. roseopersicina : accessory genes in both : pleiotrop genes (hyp) hyd: hup: (stabil) isp1 isp2 S L S L C D H I R hyp F C D E hup K hyd D
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BioHyd EU project 2. óra anyaga itt! klikk!!
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