Author
He, Wenqin
Other Contributors
Koffas, Mattheos A. G.; Linhardt, Robert J.; Barquera, Blanca L.; Karande, Pankaj;
Date Issued
2017-05
Subject
Chemical engineering
Degree
PhD;
Terms of Use
This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.;
Abstract
Chondroitin sulfate (CS) is an important glycosaminoglycan that is predominantly present in cartilage and the surfaces of many cells and extracellular matrices. It has been widely used in treating osteoarthritis due to its anti-inflammatory and chondroprotective properties. Given the importance of CS in medicine and as a dietary supplement, the traditional animal extraction method which risks virus and/or prion contamination should be replaced by a standardized bioengineering process. The general mechanism of synthesizing CS involves the enzymatic reaction of a membrane-associated sulfotransferase adding sulfo group onto the polymeric chondroitin backbone by adopting a sulfo donor 3'-phosphoadenosine 5'-phosphosulfate (PAPS). The capsular polysaccharide of pathogenic Escherichia coli K4 strain shares a similar structure to the CS precursor, chondroitin. We first overexpressed the genes involved in the biosynthesis of K4 polysaccharide in a non-pathogenic production strain BL21Star™ (DE3).; This strain produced ~2.4g/l chondroitin in DO-STAT fed-batch fermentor. The next challenge is the functional expression of membrane-associated chondroitin sulfotransferase, which typically requires post modification of N-glycosylation site. The recent success of expressing Homo sapiens chondroitin 4-sulfotransferase in BL21Star™ (DE3) by applying several protein engineering strategies enables a high level of conversion of chondroitin to CS type-A in vitro. The next challenge was improving the availability of the sulfur donor PAPS. PAPS is traditionally generated by chemical synthesis, which results in low yield and high cost. To resolve this issue, a simple and efficient enzymatic scheme was utilized by single plasmid system consisting of three related genes expressed in E. coli BL21 Star™ (DE3). With all the efforts, the metabolic engineering approach of chondroitin synthesis, expression of C4ST-1 and enzymatic synthesis of PAPS, will open up a new regime in bioengineering microbial chondroitin sulfate.;
Description
May 2017; School of Engineering
Department
Dept. of Chemical and Biological Engineering;
Publisher
Rensselaer Polytechnic Institute, Troy, NY
Relationships
Rensselaer Theses and Dissertations Online Collection;
Access
Users may download and share copies with attribution in accordance with a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License. No commercial use or derivatives are permitted without the explicit approval of the author.;