This proposal addresses continuing efforts to elucidate the structure of the lectin isolated from the garden pea (PSA) at high resolution by protein crystallographic methods. The objectives are to refine the model structure, based on a 3 angstrom electron density map, by restrained least-squares methods to an ultimate resolution of 1.2 angstroms. PSA is a 25 K dalton protein composed of two polypeptides of ca. 7K and 18K daltons, requires Mn++ and Ca++ for carbohydrate-binding activity and crystallizes as a dimer of 50K daltons. The diffracting quality of the PSA crystals offer a unique opportunity to examine this relatively large protein at high resolution (1.2 angstroms). High-resolution data will be collected on the unique facility at Daresbury, England consisting of a Arndt/Nonius T.V. detection system, synchrotron wiggler beam line and 1.0 angstrom wavelength radiation. The structure of PSA will be carefully compared with the structure of Con A in order to understand the structural implications of the unusual circularly permuted amino acid sequence compared to Con A. The analysis of similarities between the two subunits that make up the asymmetric unit in PSA crystals, Con A and a predicted structure of PSA will help in our understanding of the effect of amino acid sequences on the tertiary and quaternary structures of proteins. The details of the carbohydrate-binding site probed with both simple and complex carbohydrates will be determined by crystallographic studies of the PSA-carbohydrate complexes. These efforts will be extended to other lectins closely related to PSA by model building using computer graphics. The structure of lectin-carbohydrate complexes will help in our understanding of the specificities involved in carbohydrate-protein interactions and the recognition of carbohydrates, glycoproteins and cell surface components by proteins.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
7R01GM036610-01
Application #
3290942
Study Section
Biophysics and Biophysical Chemistry B Study Section (BBCB)
Project Start
1985-08-01
Project End
1990-04-30
Budget Start
1985-08-01
Budget End
1986-04-30
Support Year
1
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Georgia Institute of Technology
Department
Type
Schools of Arts and Sciences
DUNS #
097394084
City
Atlanta
State
GA
Country
United States
Zip Code
30332
Prasthofer, T; Phillips, S R; Suddath, F L et al. (1989) Design, expression, and crystallization of recombinant lectin from the garden pea (Pisum sativum). J Biol Chem 264:6793-6
Basu, D; Delucas, L; Parks, E H et al. (1988) Preliminary crystallographic study of the alpha-D-galactose-specific lectin from jack fruit (Artocarpus integra) seeds. J Mol Biol 201:661-2
Einspahr, H; Parks, E H; Suguna, K et al. (1986) The crystal structure of pea lectin at 3.0-A resolution. J Biol Chem 261:16518-27