title: Metabolic engineering of Pichia pastoris for production of hyaluronic acid with high molecular weight.
abstract: The high molecular weight (>1 MDa) of hyaluronic acid (HA) is important for its biological functions. The reported limiting factors for the production of HA with high molecular weight (MW) by microbial fermentation are the insufficient HA precursor pool and cell growth inhibition. To overcome these issues, the Xenopus laevis xhasA2 and xhasB genes encoding hyaluronan synthase 2 (xhasA2) and UDP-glucose dehydrogenase (xhasB), were expressed in Pichia pastoris widely used for production of heterologous proteins. In this study, expression vectors containing various combination cassettes of HA pathway genes including xhasA2 and xhasB from X. laevis as well as UDP-glucose pyrophosphorylase (hasC), UDP-N-acetylglucosamine pyrophosphorylase (hasD) and phosphoglucose isomerase (hasE) from P. pastoris were constructed and tested. First, HA pathway genes were overexpressed using pAO815 and pGAPZB vectors, resulting in the production of 1.2 MDa HA polymers. Second, in order to decrease hyaluronan synthase expression a strong AOX1 promoter in the xhasA2 gene was replaced by a weak AOX2 promoter which increased the mean MW of HA to 2.1 MDa. Finally, the MW of HA polymer was further increased to 2.5 MDa by low-temperature cultivation (26 °C) which reduced cell growth inhibition. The yield of HA production by the P. pastoris recombinant strains in 1L of fermentation culture was 0.8-1.7 g/L.
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro (373-1 Guseong-dong), Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors.forename: Euijoon
authors.initials: E
authors.lastname: Jeong
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro (373-1 Guseong-dong), Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors.forename: Woo Yong
authors.initials: WY
authors.lastname: Shim
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro (373-1 Guseong-dong), Yuseong-gu, Daejeon 305-701, Republic of Korea. Electronic address: kimjh@kaist.ac.kr.
authors.forename: Jung Hoe
authors.initials: JH
authors.lastname: Kim
mesh_terms: D000818:Animals; D001483:Base Sequence; D053898:Biosynthetic Pathways / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D004926:Escherichia coli; D005822:Genetic Vectors / Q000235:genetics; D042843:Glucose 1-Dehydrogenase / Q000235:genetics; D014453:Glucuronosyltransferase / Q000235:genetics*; D000076002:Hyaluronan Synthases; D006820:Hyaluronic Acid / Q000096:biosynthesis* / Q000737:chemistry*; D060847:Metabolic Engineering / Q000379:methods*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010843:Pichia / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013696:Temperature; D029867:Xenopus Proteins / Q000235:genetics*; D014982:Xenopus laevis / Q000235:genetics*
chemical_list: D017931:DNA Primers; D029867:Xenopus Proteins; D006820:Hyaluronic Acid; D042843:Glucose 1-Dehydrogenase; D014453:Glucuronosyltransferase; C491096:Has2 protein, Xenopus; D000076002:Hyaluronan Synthases
keywords: Hyaluronan synthase 2; Hyaluronic acid; Metabolic engineering; Molecular weight; Pichia pastoris; Xenopus laevis