Structural element, a mediator of adhesion, and an extracellular signaling molecule. The quantity and the qualities of the HA polysaccharide modulate cell behavior during development, intercellular adhesion and recognition, locomotion, and neovascularization. The long-term goal of this investigation is to elucidate the structure and the mechanism of action of the HA synthase enzymes responsible for production of HA in humans. The biosynthesis of HA in vertebrates has been studied for decades with little success until 1996, when a family of eukaryotic HA synthases was identified. These enzymes are novel and interesting glycosyltransferases because they transfer two different sugar groups during polymerization; almost all other enzymes transfer only one sugar. The molecular and biochemical details of HA biosynthesis in vertebrates are lacking. Therefore, the major goal of this five-year project period is to characterize several HA synthases from Xenopus and humans. The investigators have produced functional recombinant xenopus HA synthase enzyme in a background-free system.
The specific aims of this project are; 1) To analyze the kinetics of the eukaryotic HA synthases. Classical biochemical studies will reveal the manner in which the enzyme polymerizes its UDP-sugar precursors. 2) To characterize structurally the eukaryotic HA synthases. Radiation inactivation and mass spectrometry will be used to define the functional unit and monomer sizes, respectively. 3) To identify the precursor binding sites of the HA synthases. photoaffinity and chemical labeling studies will be utilized ot tag regions of the enzyme that interact with the UDP-sugar substrates. 4) To determine the functional residues of the HA synthase. The residues that are conserved among HA synthases will be altered by site-directed mutagenesis; in particular, certain cysteine residues will be mutated due to their potential roles in catalysis and in disulfide bond formation. The essential residues identified in aim 3 will also be confirmed by mutagenesis studies. The enzymological and structural information may allow the generation of a working model describing the catalytic mechanism of these enzymes.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM056497-04
Application #
6181279
Study Section
Physiological Chemistry Study Section (PC)
Program Officer
Marino, Pamela
Project Start
1997-07-01
Project End
2003-06-30
Budget Start
2000-07-01
Budget End
2003-06-30
Support Year
4
Fiscal Year
2000
Total Cost
$149,015
Indirect Cost
Name
University of Oklahoma Health Sciences Center
Department
Biochemistry
Type
Schools of Medicine
DUNS #
937727907
City
Oklahoma City
State
OK
Country
United States
Zip Code
73117
Pummill, Philip E; Kane, Tasha A; Kempner, Ellis S et al. (2007) The functional molecular mass of the Pasteurella hyaluronan synthase is a monomer. Biochim Biophys Acta 1770:286-90
Weigel, Paul H; DeAngelis, Paul L (2007) Hyaluronan synthases: a decade-plus of novel glycosyltransferases. J Biol Chem 282:36777-81
DeAngelis, Paul L; Oatman, Leonard C; Gay, Daniel F (2003) Rapid chemoenzymatic synthesis of monodisperse hyaluronan oligosaccharides with immobilized enzyme reactors. J Biol Chem 278:35199-203
Jing, Wei; DeAngelis, Paul L (2003) Analysis of the two active sites of the hyaluronan synthase and the chondroitin synthase of Pasteurella multocida. Glycobiology 13:661-71
Pummill, Philip E; DeAngelis, Paul L (2003) Alteration of polysaccharide size distribution of a vertebrate hyaluronan synthase by mutation. J Biol Chem 278:19808-14
DeAngelis, Paul L (2002) Evolution of glycosaminoglycans and their glycosyltransferases: Implications for the extracellular matrices of animals and the capsules of pathogenic bacteria. Anat Rec 268:317-26
DeAngelis, Paul L; White, Carissa L (2002) Identification and molecular cloning of a heparosan synthase from Pasteurella multocida type D. J Biol Chem 277:7209-13
Pummill, Philip E; DeAngelis, Paul L (2002) Evaluation of critical structural elements of UDP-sugar substrates and certain cysteine residues of a vertebrate hyaluronan synthase. J Biol Chem 277:21610-6
DeAngelis, Paul L (2002) Microbial glycosaminoglycan glycosyltransferases. Glycobiology 12:9R-16R
Pummill, P E; Kempner, E S; DeAngelis, P L (2001) Functional molecular mass of a vertebrate hyaluronan synthase as determined by radiation inactivation analysis. J Biol Chem 276:39832-5

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