Vergangene Seminare seit 2016

Gastgeber: Dr. Georg Hochberg

A chromosome-encoded ParMR system that forms membrane-bound filaments regulating cell shape in Cyanobacteria

Microbiology Seminar Series
Cytochrome P450 enzymes are catalysts of unrivalled versatility, able to mediate over 60 different monooxygenation and other reactions, such as aromatic and aliphatic hydroxylation at unactivated C-H bonds, epoxidation of olefins and aromatic rings, heteroatom oxidation and dealkylation, C-C bond cleavage, ring rearrangements, isomerizations and reductions. This catalytic versatility has led to the exploitation of P450s across the biosphere, for diverse functions such as the mobilization of carbon sources, chemical communication (e.g. hormonal signalling), and inter-organismal chemical warfare, such as between plants and the herbivores that feed on them. They were pivotal for the transition from water to land by plants and animals and play central roles in natural product biosynthesis in microbes and secondary metabolism in plants. This versatility also makes them attractive for catalyzing industrially important reactions in pharmaceutical and other fine chemical syntheses. However, P450 enzymes from natural sources are limited by poor stability and the need for accessory enzymes and a reducing cofactor. Moreover, expression of P450s in recombinant systems typically requires rich media, all of which increases the cost of using P450s for industrial biocatalysis. We have used ancestral sequence reconstruction as a technique for both engineering P450s as biocatalysts and exploring their evolution. This presentation will look both backwards and forwards. Using examples drawn from reconstructions of plant, animal and microbial P450 families, I will discuss what we have learned about the natural evolution of these enzymes. Then, I will show how ancestral P450s can be used as cost-effective, modular bio-bricks for synthetic biology, to create biocatalytic systems powered by photosynthesis and nanobioreactors based on P450s in virus-like particles. Cytochrome P450 enzymes are catalysts of unrivalled versatility, able to mediate over 60 different monooxygenation and other reactions, such as aromatic and aliphatic hydroxylation at unactivated C-H bonds, epoxidation of olefins and aromatic rings, heteroatom oxidation and dealkylation, C-C bond cleavage, ring rearrangements, isomerizations and reductions. This catalytic versatility has led to the exploitation of P450s across the biosphere, for diverse functions such as the mobilization of carbon sources, chemical communication (e.g. hormonal signalling), and inter-organismal chemical warfare, such as between plants and the herbivores that feed on them. They were pivotal for the transition from water to land by plants and animals and play central roles in natural product biosynthesis in microbes and secondary metabolism in plants. This versatility also makes them attractive for catalyzing industrially important reactions in pharmaceutical and other fine chemical syntheses. However, P450 enzymes from natural sources are limited by poor stability and the need for accessory enzymes and a reducing cofactor. Moreover, expression of P450s in recombinant systems typically requires rich media, all of which increases the cost of using P450s for industrial biocatalysis. We have used ancestral sequence reconstruction as a technique for both engineering P450s as biocatalysts and exploring their evolution. This presentation will look both backwards and forwards. Using examples drawn from reconstructions of plant, animal and microbial P450 families, I will discuss what we have learned about the natural evolution of these enzymes. Then, I will show how ancestral P450s can be used as cost-effective, modular bio-bricks for synthetic biology, to create biocatalytic systems powered by photosynthesis and nanobioreactors based on P450s in virus-like particles. [mehr]

Ask the ancestors: resurrecting and re-evolving the bacterial flagellar motor

Guest Speaker Talk

The evolution of the molecular toolkit for pluripotent stem cells

We use native and re-designed versions of SOX and OCT transcription factors to reprogram somatic cells into induced pluripotent stem cells and for stem cell engineering. In mammals, what distinguishes paralogous SOX factors is their ability to dimerize with OCT4 on distinctive composite DNA elements to induce stemness (SOX2) or specify the germline (SOX17). The selective partnership of these two SOX factors with OCT4 is primarily directed by a single amino acid conserved across animals. Mutating this amino acid converts SOX17 into an enhanced 'super SOX2', termed eSOX17, which speeds up pluripotency induction. In human cells, eSOX17 enables the direct conversion of somatic cells into totipotent cells. In two-factor cocktails, eSOX17 can transdifferentiate human blood into induced brain stem cells, avoiding the rejuvenation associated with pluripotency induction. Inspired by the close partnership between SOX/OCT and the potential of re-engineered variants for cellular reprogramming, we have begun to study their evolutionary history. Until now, SOX and OCT factors have been believed to be unique to animals. Surprisingly, we identified these factors in certain lineages of unicellular holozoans and found that they can replace SOX2 to induce pluripotency in mice. It is possible that the emergence of the molecular toolkit essential for mammalian pluripotency predates the evolution of multicellularity. [mehr]

Microbial determinants of folivory in beetles

Microbiology Seminar Series

Phylogenomics and the early evolution of Bacteria

Microbiology Seminar Series

Evolution of high torque flagellar motors and coevolution of cell plan in the Campylobacterota

Microbiology Seminar Series
Zur Redakteursansicht