Biosynthesis of isoprenoids, polyunsaturated fatty acids and flavonoids in Saccharomyces cerevisiae

Industrial biotechnology employs the controlled use of microorganisms for the production of synthetic chemicals or simple biomass that can further be used in a diverse array of applications that span the pharmaceutical, chemical and nutraceutical industries. Recent advances in metagenomics and in the incorporation of entire biosynthetic pathways into Saccharomyces cerevisiae have greatly expanded both the fitness and the repertoire of biochemicals that can be synthesized from this popular microorganism. Further, the availability of the S. cerevisiae entire genome sequence allows the application of systems biology approaches for improving its enormous biosynthetic potential. In this review, we will describe some of the efforts on using S. cerevisiae as a cell factory for the biosynthesis of high-value natural products that belong to the families of isoprenoids, flavonoids and long chain polyunsaturated fatty acids. As natural products are increasingly becoming the center of attention of the pharmaceutical and nutraceutical industries, the use of S. cerevisiae for their production is only expected to expand in the future, further allowing the biosynthesis of novel molecular structures with unique properties.     

An investigation of the carboxyl group function in the active center of transketolase

Transketolase from baker's yeast is rapidly inactivated in the presence of 1-ethyl-3 (3'-dimethylaminopropyl)-carbodiimide. pKa of the modified carboxyl groups is approximately 6.5. An investigation of the initial steps of enzymatic catalysis monitored by a changes in the circular dichroism spectra and in an oxidation reaction with ferricyanide made it possible to conclude that the modification interferes with the donor substrate attachment to the enzyme. Evidence obtained was suggesting that the carboxyl group of the active center facilitates dissociation of a proton from the carbon atom in the second position of the thiamine pyrophosphate thiazolium ring.     

Functional Flexibility of the Transketolase Molecule

Transketolase is the simplest representative of the thiamine diphosphate-dependent enzymes. It was the first of these enzymes for which X-ray analysis was performed. Based on the data of X-ray studies and using the mutagenesis technique, the nature of functional groups of the enzyme involved in the interaction with substrates and cofactors and in the coenzyme activation was defined. Thus, considerable achievements have been made in studying the structure of transketolase. However, there is relatively little information on the conformational flexibility of the enzyme molecule while it is functioning, i.e., during its interaction with cofactors and substrates and in the course of intermediate product formation. This review summarizes mainly the results obtained in the author's group, as well as those rare data on this subject that could be found in literature.