Important Milestone in Quest for Hydrogen Production Using Photosynthesis

Hydrogen gas has long been proposed as a promising energy carrier for future energy applications, but generating the gas from water has proved inefficient. Researchers at Uppsala University have now managed to activate a key enzyme called hydrogenase in E. coli bacteria, which opens the door to future applications in photosynthesising microorganisms.

intestinal tumours, molecular scissors, disease, genetic, immune cells, drug development, Diabetes, Antibiotic, hydrogen generation, chronic obstructive pulmonary disease, malaria, photosynthesis, kidney failure, Brain tumours, mental health, blood cancer, cancer, dementia, cancer treatment, antibiotic resistance, blood vessel leakage, quantum simulations, atrial fibrillation, batteries, goiter treatment, terahertz radiation, organic materials , Guild of European Research Intensive Universities, gene copies, social anxiety, blue light screens, ‘Our hope is that these findings will make it possible to discover a way to selectively inhibit the TGF-beta signals that stimulate tumour development without knocking out the signals that inhibit tumour development, and that this can eventually be used in the fight against cancer,’ says Eleftheria Vasilaki, postdoctoral researcher at Ludwig Institute for Cancer Research at Uppsala University and lead author of the study. TGF-beta regulates cell growth and specialisation, in particular during foetal development. In the context of tumour development, TGF-beta has a complicated role. Initially, it inhibits tumour formation because it inhibits cell division and stimulates cell death. At a late stage of tumour development, however, TGF-beta stimulates proliferation and metastasis of tumour cells and thereby accelerates tumour formation. TGF-beta’s signalling mechanisms and role in tumour development have been studied at the Ludwig Institute for Cancer Research at Uppsala University for the past 30 years. Recent discoveries at the Institute, now published in the current study in Science Signaling, explain part of the mechanism by which TGF-beta switches from suppressing to enhancing tumour development. Uppsala researchers, in collaboration with a Japanese research team, discovered that TGF-beta along with the oncoprotein Ras, which is often activated in tumours, affects members of the p53 family. The p53 protein plays a key role in regulating tumour development and is often altered – mutated – in tumours. TGF-beta and Ras suppress the effect of mutated p53, thereby enhancing the effect of another member of the p53 family, namely delta-Np63, which in turn stimulates tumour development and metastasis.

The method involves inserting designed molecules into genetically modified E. coli bacteria to induce an otherwise inactive enzyme to start producing hydrogen gas. In other words, the method uses a combination of synthetic chemistry and biology.

Troublesome enzyme: the iron-iron-hydrogenase

Generating renewable hydrogen gas from water is feasible, but current systems for achieving this are limited. Nature’s enzymes that produce hydrogen gas in bacteria and algae are the ‘iron-iron-hydrogenases’. These enzymes have a very high capacity and have long interested scientists. However, they exist only in specific microorganisms that require special culture conditions, and to date have therefore only been used in small-scale laboratory experiments. Large-scale production of iron-iron-hydrogenases in bacteria relevant to biotechnological applications has yielded an inactive, unusable enzyme form.

It is this unusable enzyme that the scientists now have succeeded in activating, in genetically modified organisms, by combining it with designed synthetic molecules.

“We can modify selected organisms genetically and insert the gene encoding the enzyme into more easily manageable bacteria, and then activate it using our synthetic iron compounds. These artificially activated enzymes have proved fully functional, and transformE. coli bacteria into cellular hydrogen-gas factories,” says Professor Peter Lindblad.

He and his research colleague Gustav Berggren have jointly led the work at the Department of Chemistry – Ångström Laboratory.

Next: Hydrogen production in photosynthesising microorganisms

The scientists are now proceeding to apply the technique to photosynthetic microorganisms that get their energy from sunlight, instead of bacteria that need a constant nutrient supply. They want to further improve the artificial enzymes at genetic level and also enhance the process by modifying the synthetic catalysts.

“If we manage to refine the method as planned, it has the potential to make biological production of hydrogen gas from sunlight and water markedly easier,” says group leader Gustav Berggren.

The article In vivo activation of an [FeFe] hydrogenase using synthetic cofactorswas published in Energy and Environmental Science on 11 April 2017.