RESEARCH OVERVIEW

Natural biodiversity is now increasingly searched not only for new pharmacological compounds (particularly for diseases where our present range of drugs is less or not effective, or loses its effectiveness as in the alarming case of many antibiotics) but also for new sources of these compounds. Instead of screening natural biodiversity for sources of these compounds, we have taken another approach where we harness the biosynthetic machineries of cells to synthesize and create new structural diversity of small molecules.

Efforts in genome sequencing give us access to an incredible number of biosynthetic genes that we can use to assemble biosynthetic reaction sequences in heterologous hosts much like the synthetic reaction sequences performed by an organic chemist. Not only can we combine enzyme functions in reaction sequences for desired small molecules, but by changing and matching the catalytic functions of assembled enzymes we can broaden the diversity of synthesized compounds and even produce new, unnatural compounds.

In nature, metabolic pathways have evolved by gene duplication followed by recruitment of genes into new pathways and mutation and selection of improved catalytic functions. We are following nature's strategy of metabolic evolution by recruiting genes from different organisms and pathways and matching catalytic functions using random and, if possible, protein structure guided in vitro evolution strategies.

Our research endeavors combine methods and strategies from several disciplines including analytical chemistry, engineering, biochemistry and bioinformatics. As biochemists our research activities are not only focused on the engineering of biosynthetic machineries to make useful compounds, but a major focus is also directed at understanding the functions and catalytic plasticity of the combined enzymes and from there, generate a better understanding of metabolic pathways. In vitro evolution experiments, random or structure-guided, provide us with new insights into the function of enzymes. Reconstituting biosynthetic pathways into a heterologous host such as E. coli that does not synthesize the class of compounds being investigated, allows the investigation of biosynthetic functions in a background free in vivo setting. This is particularly useful when investigating enzyme functions encoded by gene sequences obtained by mining of microbial and plant genomes as it allows rapid experimental confirmation or rejection of computationally annotated functions in genome sequences.

We are currently studying and redesigning the biosynthetic machineries of three compound classes - isoprenoids, flavonoids & porphyrins - using the approaches described above. These compounds have important applications as agrochemicals, therapeutics, pharmaceuticals, nutraceuticals and materials.