Abstract

Gangliosides contain complex carbohydrates attached to lipids and play essential roles in cell signaling. The GM2 activator protein (GM2-AP) is an essential cofactor in mammalian lysosomes for conversion of GM2 to GM3 by beta-hexosaminidase A. Deficiency of GM2-AP results in type AB Tay Sachs disease, a fatal genetic disorder. To investigate the specific activating function of GM2-AP and its affinity for glycolipid acyl chains, x-ray structures of both human and mouse GM2-AP are being determined as well as the structure of the mouse GM2 ligand complex. The crystal structure of the selenomethionine mutant of the GM2-AP has been solved at 2.4 A by multiwavelength anomalous diffraction. The plan is to refine the human GM2-AP structure and to solve the apo-mouse GM2-AP and its complex with GM2 at 2.5 A by molecular replacement. The resulting molecular models will be analyzed for conformational differences. Additional structural studies of human Tay Sachs mutants (R138P and C107R) will further unravel the functional role of specific protein side chains in the disease. Finally, to investigate how gangliosides are recognized in other proteins, new structural studies are proposed on sulfatide activator protein (SAP-B), a small dimeric protein known to stimulate the hydrolysis of GM1 by beta-galactosidase.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM060603-03
Application #
6526066
Study Section
Biophysical Chemistry Study Section (BBCB)
Program Officer
Flicker, Paula F
Project Start
2000-09-01
Project End
2004-08-31
Budget Start
2002-09-01
Budget End
2003-08-31
Support Year
3
Fiscal Year
2002
Total Cost
$212,266
Indirect Cost

  Institution

Name
University of Virginia
Department
Pharmacology
Type
Schools of Medicine
DUNS #
001910777
City
Charlottesville
State
VA
Country
United States
Zip Code
22904

  Publications

Carter, Jeffery D; Mathias, Jordan D; Gomez, Edwin F et al. (2014) Characterizing solution surface loop conformational flexibility of the GM2 activator protein. J Phys Chem B 118:10607-17
Wright, Christine S; Mi, Li-Zhi; Lee, Sangderk et al. (2005) Crystal structure analysis of phosphatidylcholine-GM2-activator product complexes: evidence for hydrolase activity. Biochemistry 44:13510-21
Wright, Christine S; Mi, Li-Zhi; Rastinejad, Fraydoon (2004) Evidence for lipid packaging in the crystal structure of the GM2-activator complex with platelet activating factor. J Mol Biol 342:585-92
Wright, Christine Schubert; Zhao, Qiang; Rastinejad, Fraydoon (2003) Structural analysis of lipid complexes of GM2-activator protein. J Mol Biol 331:951-64
Sun, Q A; Kirnarsky, L; Sherman, S et al. (2001) Selenoprotein oxidoreductase with specificity for thioredoxin and glutathione systems. Proc Natl Acad Sci U S A 98:3673-8