UDP-glucuronic acid heterologous production in Escherichia coli and Saccharomyces cerevisiae chassis

Abstract

Glycosaminoglycans (GAG) such as hyaluronic acid and chondroitin sulfate are nutraceuticals with important medical and cosmetic applications. Usually, these compounds are extracted from animal sources, though concerns on animal products use are driving the search for alternative GAG sources. Some pathogenic bacterial strains naturally produce GAG like polysaccharides through identified pathways which have been the basis for their biotechnological production using non pathogenic hosts. Uridine diphosphate (UDP)-glucose dehydrogenase (UGD) catalyzes a common step in GAG biosynthetic pathways that generates UDP-glucuronic acid (GlcA) reported as the limiting substrate for GAG production However, few UGD genes have been evaluated for pathway optimization. In the present work, Escherichia coli and Saccharomyces cerevisiae expressing alternative heterologous UGD genes have been constructed. Three UGD genes originally from different genomic sources (Capra hircus, Zymomonas mobilis, Lactobacillus johnsonii) were expressed in S. cerevisiae strains and in vivo UDP GlcA production was achieved up to 7.2 µmol/ g cells. The two prokaryotic UGD genes were also expressed in E. coli BL21 which resulted in up to 23.6 µmol/ g cells UDP GlcA The activity of the recombinant UGD enzymes was also evaluated through in vitro reactions using cell extracts This work reveals promising alternative enzymes for industrial GAGs production using heterologous hosts In particular, the expression of the eukaryotic ChUGD gene and the use of S. cerevisiae system were herein explored for the first time.