Scientist, Boston Biomedical Research Institute.
Education
Research Interests
Ephrin-Eph Receptor Interactions
Ephrins, which are membrane bound ligands for the Eph receptor tyrosine kinases, and the Eph receptors themselves are the focus of structural studies in our lab. We have recently completed the 1.92 Angstrom crystal structure of the ephrin-B2 ectodomain (Developmental Cell, Vol. 1, n. 1, pp. 83-92.). The ephrin-B2 ectodomain has a greek topology stabilized by two disulfide bonds. A hydrophobic patch on the surface is the target for our directed-drug design studies, and we have an active collaboration with Dr. Laura Benjamin to do angiogenesis studies of ephrin-B2 and potential inhibitors of angiogenesis via ephrin-B2.
We are actively pursuing the crystallization and preparation of complexes of ephrins and Eph receptors for X-ray crystallography and single-particle image analysis. We also are analyzing ephrin-Eph interactions thermodynamically using our own ITC.
Funding: NIH R01 HL69707 Stuctural studies of an angiogenic protein, ephrin-B2.
GrpE-DnaK Interactions
The regulation of nucleotide hydrolysis is an important aspect of many cellular functions including protein folding via molecular chaperone pathways and signal transduction pathways. Nucleotide exchange factors promote the dissociation of spent nucleotide diphosphates from nucleotide binding proteins, so that nucleotide triphosphates can be bound once more. GrpE, SOS (son of sevenless), EfTs, and 7-transmembrane receptors are examples of proteins that act as nucleotide exchange factors.We study nucleotide exchange in the prokaryotic DnaK-DnaJ-GrpE cycle. DnaK is a molecular chaperone (Hsp70 analog) that couples peptide binding and release to ATP binding and hydrolysis. The hydrolysis of ATP to ADP by the ATPase domain of DnaK causes the polypeptide substrate of DnaK to be released from the peptide binding domain, through a mechanism that is still unknown. The nucleotide exchange factor GrpE then promotes the rapid dissociation of the otherwise tightly held ADP from DnaK. The crystal structure of the complex of GrpE and the ATPase domain of DnaK has been solved, and forms the basis for much of the research interests in the lab. The main emphasis of research is structural studies of GrpE-DnaK complexes, and homologous complexes from mitochondria and thermophiles, using X-ray crystallographic techniques. Also of crystallographic interest are other molecular chaperones including DnaJ, and the eukaryotic analogs, Hsp70 and Hsp40. Structure-function studies of GrpE-DnaK interactions are being undertaken to address the question of the discrimination of the ATP and ADP states of DnaK by GrpE, the functional epitope of GrpE-DnaK binding, and the displacement of GrpE from the ATP bound state of DnaK. Of extra interest is the structure-function relationship of the N-terminus of GrpE, which facilitates polypeptide release from DnaK.
Progress has been made in our lab regarding the interaction of GrpE and DnaK under constant-nucleotide conditions, which we study by sedimentation velocity analytical centrifugation. We have just completed an in-depth study of GrpE mutants by circular dichroism and are preparing a manuscript. Crystallographic studies of mutant GrpE-DnaK complexes are underway to augment our thermodynamic and kinetic analyses.
Funding: NIH R01 GM58256 Structure-function analysis of molecular chaperones.
Return to Bohm & Harrison Home PageSelected Publications
Joseph Toth, Tyler Cutforth, Amy D. Gelinas, Kelley E. Bethoney, Joel Bard, and Celia J. Harrison, 2001. "Crystal Stucture of an Ephrin Ectodomain." Developmental Cell, 1:83-92.
Celia J. Harrison, 1997. "La Cage Aux Fold: asymmetry in the crystal structure of GroEL-GroES-(ADP)7". (Review) Structure 5: 1261-1264.
Celia J. Harrison, Manajit Hayer-Hartl, Maurizio Di Liberto, F.-Ulrich Hartl and John Kuriyan, 1997. "Crystal structure of the nucleotide exchange factor GrpE bound to the ATPase domain of the molecular chaperone DnaK". Science 276:431-435.
Fred F. Damberger, Jeff G. Pelton, Corey Liu, Ho Cho, Celia. J. Harrison, Hillary C.M. Nelson, and Dave E. Wemmer, 1995. "Refined solution structure and dynamics of the DNA-binding domain of the heat-shock factor from Kluyveromyces lactis." J. Mol. Biol. 254: 704-719.
Fred F. Damberger, Jeff G. Pelton, Celia. J. Harrison, Hillary C.M. Nelson, and Dave E. Wemmer, 1994. "Solution Structure of the DNA-binding domain of the heat shock transciption factor determined by multidimensional heteronuclear magnetic resonance spectroscopy." Protein Sci. 3: 1806-21.
Karen E. Flick, Lino Gonazalez Jr., Celia J. Harrison, and Hillary C.M. Nelson, 1994."Yeast heat shock transcription factor contains a flexible linker between the DNA-binding and trimerization domains. Implications or DNA binding by trimeric proteins." J. Biol. Chem. 269: 12475-81.
Celia J. Harrison, A. Andrew Bohm, and Hillary C.M. Nelson, 1994. "Crystal structure of the DNA binding domain of the heat shock transcription factor." Science, 263: 224-27.