title: Engineering a branch of the UDP-precursor biosynthesis pathway enhances the production of capsular polysaccharide in Escherichia coli O5:K4:H4.
abstract: Escherichia coli K4 produces a capsule with a chemical structure that resembles chondroitin, a molecule with established chondro protective properties. The endogenous genes pgm and galU are involved in the biosynthesis of UDP-glucose which is a critical intermediate in carbohydrate metabolism and biochemical precursor of UDP-glucuronic acid. Together with UDP-N-acetylgalactosamine, UDP-glucuronic acid is used as sugar donor for capsule biosynthesis. The aim of the study was to evaluate how a change in the pathways leading to UDP-glucuronic acid biosynthesis affected capsular polysaccharide production. One additional copy of pgm and galU was introduced in E. coli K4 and in the previously described recombinant strain EcK4r3. A microbioreactor was used to analyse strain performance with parallel batch experiments, demonstrating increased polysaccharide concentrations and providing data that are comparable to those obtained in larger fermenters. Further experiments on a glutamine enriched medium showed an additional 45% increase of capsule production, maybe indicating the need to balance both branches leading to polymer biosynthesis in order to maximize yields. In the effort towards the establishment of a feasible bio-chondroitin production process this study provides information on how the availability of sugar precursors impacts polysaccharide biosynthesis in E. coli K4, a complex unexplored aspect of a multifaceted process.
authors.affiliation: Department of Experimental Medicine, Section of Biotechnology and Molecular Biology, Second University of Naples, Naples, Italy. donatella.cimini@unina2.it.
authors.forename: Donatella
authors.initials: D
authors.lastname: Cimini
authors.affiliation: Department of Experimental Medicine, Section of Biotechnology and Molecular Biology, Second University of Naples, Naples, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Carlino
authors.affiliation: Department of Biochemistry Biophisics and General Pathology, Second University of Naples, Naples, Italy.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Giovane
authors.affiliation: Department of Experimental Medicine, Section of Biotechnology and Molecular Biology, Second University of Naples, Naples, Italy.
authors.forename: Ottavia
authors.initials: O
authors.lastname: Argenzio
authors.affiliation: Department of Experimental Medicine, Section of Biotechnology and Molecular Biology, Second University of Naples, Naples, Italy.
authors.forename: Ileana
authors.initials: I
authors.lastname: Dello Iacono
authors.affiliation: Department of Experimental Medicine, Section of Biotechnology and Molecular Biology, Second University of Naples, Naples, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: De Rosa
authors.affiliation: Department of Experimental Medicine, Section of Biotechnology and Molecular Biology, Second University of Naples, Naples, Italy. chiara.schiraldi@unina2.it.
authors.forename: Chiara
authors.initials: C
authors.lastname: Schiraldi
mesh_terms: D016667:Bacterial Capsules / Q000235:genetics / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology; D002807:Chondroitin; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D060847:Metabolic Engineering / Q000379:methods*; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase / Q000235:genetics / Q000378:metabolism; D014532:Uridine Diphosphate Glucose / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D002807:Chondroitin; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase; C121039:galU protein, E coli; D014532:Uridine Diphosphate Glucose
keywords: Chondroitin; Escherichia coli K4; GalU overexpression; Pgm overexpression; UDP-sugar pools