Irreversible Glucuronyl C5-epimerization in the Biosynthesis of Heparan Sulfate

Hagner-McWhirter, Åsa; Li, Jinping; Oscarson, Stefan; Lindahl, Ulf

doi:10.1074/jbc.m313760200

Cited by 40 publications

(29 citation statements)

References 31 publications

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“…This result agrees with previous studies of solubilized microsomal enzyme, which showed a freely reversible reaction with favored retention of D-gluco configuration (20). Similar findings applied to solubilized HS epimerase (21), which, however, was found to act in essentially irreversible mode in the intact cell (22). The intracellular epimerase reactions are presumably closely associated with O-sulfation steps (12, 38 -40) that preclude "back epimerization" and thus promote generation of IdoUA-containing structures.…”

Section: Discussionsupporting

confidence: 82%

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Biosynthesis of Dermatan Sulfate

Maccarana

Olander

Malmström

et al. 2006

Journal of Biological Chemistry

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138

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We identified the gene encoding chondroitin-glucuronate C5-epimerase (EC 5.1.3.19) that converts D-glucuronic acid to L-iduronic acid residues in dermatan sulfate biosynthesis. The enzyme was solubilized from bovine spleen, and an ϳ43,000-fold purified preparation containing a major 89-kDa candidate component was subjected to mass spectrometry analysis of tryptic peptides. SART2 (squamous cell carcinoma antigen recognized by T cell 2), a protein with unknown function highly expressed in cancer cells and tissues, was identified by 18 peptides covering 26% of the sequence. Transient expression of cDNA resulted in a 22-fold increase in epimerase activity in 293HEK cell lysate. Moreover, overexpressing cells produced dermatan sulfate chains with 20% of iduronic acid-containing disaccharide units, as compared with 5% for mock-transfected cells. The iduronic acid residues were preferentially clustered in blocks, as in naturally occurring dermatan sulfate. Given the discovered identity, we propose to rename SART2 (Nakao, M., Shichijo, S., Imaizumi, T., Inoue, Y., Matsunaga, K., Yamada, A., Kikuchi, M., Tsuda, N., Ohta, K., Takamori, S., Yamana, H., Fujita, H., and Itoh, K. (2000) J. Immunol. 164, 2565-2574) with a functional designation, chondroitin-glucuronate C5-epimerase (or DS epimerase). DS epimerase activity is ubiquitously present in normal tissues, although with marked quantitative differences. It is highly homologous to part of the NCAG1 protein, encoded by the C18orf4 gene, genetically linked to bipolar disorder. NCAG1 also contains a putative chondroitin sulfate sulfotransferase domain and thus may be involved in dermatan sulfate biosynthesis. The functional relation between dermatan sulfate and cancer is unknown but may involve known iduronic acid-dependent interactions with growth factors, selectins, cytokines, or coagulation inhibitors. Proteoglycans consist of glycosaminoglycan (GAG)5 chains covalently linked to core proteins. The GAGs play important roles in mediating biological functions of proteoglycans, mainly due to their ability to interact with a variety of proteins (1-5). Chondroitin sulfate (CS)/dermatan sulfate (DS) proteoglycans carry GAGs composed of alternating units of GalNAc and GlcA, or IdoUA in the case of DS. The chondroitin/CS/DS family has been ascribed a variety of physiological/developmental effects that range from control of basic cellular processes such as cell division in Caenorhabditis elegans, scaffold functions in various types of connective tissue, to highly cell type-specific effects, as exemplified by the neurite outgrowthpromoting activity mediated by rare structures in cerebral CS/DS (6 -9). Protein ligands targeted by CS/DS include growth factors, modulators of blood coagulation, selectins, and chemokines. It is important to define the CS/DS structures involved in selective protein binding and to understand how they are generated. The IdoUA-containing domains of DS chains are of particular significance in this regard, because IdoUA residues endow conformational flexibili...

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Section: Discussionsupporting

confidence: 82%

“…The resulting labeled K4 polysaccharides were defructosylated (dK4). HS epimerase substrate was generated in an analogous manner by incubating E. coli K5 bacteria with D- [5-3 H]glucose, followed by N-deacetylation and N-sulfation of the resultant radiolabeled polysaccharide (21,22).…”

Section: Methodsmentioning

confidence: 99%

Biosynthesis of Dermatan Sulfate

Maccarana

Olander

Malmström

et al. 2006

Journal of Biological Chemistry

Self Cite

138

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“…[16][17][18] However, recent data demonstrates importance of the epimerase in development and normal functioning of living organisms. It was shown that targeted disruption of a glucuronyl C5-epimerase gene in mice results in heparan sulfate lacking L-Iduronic Acid and in neonatal lethality.…”

Section: Discussionmentioning

confidence: 99%

Decreased expression of human D‐glucuronyl C5‐epimerase in breast cancer

Grigorieva¹,

Eshchenko²,

Рыкова³

et al. 2007

Intl Journal of Cancer

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D-glucuronyl C5-epimerase (GLCE) is one of the key enzymes in proteoglycan biosynthesis. However, nothing is known about expression and activity of the protein in cancer. In this study, we investigated GLCE expression in human breast cancer using multipex RT-PCR, QRT-PCR and Western-blot assays. In total, 21 patients without malignancy and 74 patients with breast tumor were investigated. The obtained data showed that in 82-84% of human breast tumors there is either downregulation or loss of Dglucuronyl C5-epimerase mRNA expression and significant decrease of the protein content. In most cases (77%), GLCE expression was decreased also in the normal-appearing tissue surrounding the tumor node but the protein amount was comparable to normal breast tissue. These findings represent the first data about involvement of human D-glucuronyl C5-epimerase in malignant transformation. ' 2007 Wiley-Liss, Inc.

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“…The next enzyme in line is the C5-epimerase, specific for b-D-GlcA residues glycosylated at the 4-position with NS glucosamine (Hagner-McWhirter et al, 2004). The disaccharide in HS, a minor component of heparin (-4 (Maruyama et al, 1998 Pharmacology of Heparin and Related Drugs crystal structure of this enzyme (the sequence from Danio rero) in complex with a heparin oligosaccharide was recently solved (4PXQ.pdb) and compared with the unbound enzyme (4PW2.pdb) (Qin et al, 2015).…”

Section: A Biosynthesismentioning

confidence: 99%