Muscle contraction is switched """"""""on"""""""" and """"""""off"""""""" in response to external chemical or electrical signals. Within each muscle cell activation is controlled by calcium ions and regulatory proteins: at high levels of calcium the muscle is """"""""on"""""""", at lower levels the muscle is """"""""off"""""""". This calcium switch consists of the proteins tropomyosin and troponin. Using X-ray crystallography together with electron microscopy I propose to determine the detailed three-dimensional structure of tropomyosin, visualize its interactions with troponin in the crystal lattice, and prepare crystals of troponin and/or its subfragments for high resolution structure determination. This information will allow us to better understand how these proteins control contraction. Motions of tropomyosin have been postulated to play a critical role in the regulatory process. The flexibility of tropomyosin in the crystals will be examined by analyzing the diffuse X-ray scattering in conjunction with crystallographic studies at various temperatures. These results will allow us to determine the kinds of motions and conformations which tropomyosin can adopt during the regulatory process. Although tropomyosin was first discovered in muscle cells, we have recently recognized that this protein plays an important role in the cytoskeleton of many cells. Moreover, tropomyosin-like proteins have been found at the surface of certain pathogenic bacteria, and appear to be critical factors in determining their virulence. Attempts will be made to characterize the molecular structure of one of these proteins from streptococcal bacteria. Knowledge of how this """"""""M protein"""""""" works could be significant in developing ways to control streptococcal diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR032764-07
Application #
3156396
Study Section
Biophysical Chemistry Study Section (BBCB)
Project Start
1984-04-01
Project End
1992-05-31
Budget Start
1990-06-01
Budget End
1991-05-31
Support Year
7
Fiscal Year
1990
Total Cost
Indirect Cost
Name
Rice University
Department
Type
Schools of Arts and Sciences
DUNS #
050299031
City
Houston
State
TX
Country
United States
Zip Code
77005
Berry, Michael B; Bae, Euiyoung; Bilderback, Tim R et al. (2006) Crystal structure of ADP/AMP complex of Escherichia coli adenylate kinase. Proteins 62:555-6
Soman, J; Tao, T; Phillips Jr, G N (1999) Conformational variation of calcium-bound troponin C. Proteins 37:510-1
Berry, M B; Phillips Jr, G N (1998) Crystal structures of Bacillus stearothermophilus adenylate kinase with bound Ap5A, Mg2+ Ap5A, and Mn2+ Ap5A reveal an intermediate lid position and six coordinate octahedral geometry for bound Mg2+ and Mn2+. Proteins 32:276-88
Phillips Jr, G N (1997) Structure and dynamics of green fluorescent protein. Curr Opin Struct Biol 7:821-7
Phillips Jr, G N; Chacko, S (1996) Mechanical properties of tropomyosin and implications for muscle regulation. Biopolymers 38:89-95
Hnath, E J; Wang, C L; Huber, P A et al. (1996) Affinity and structure of complexes of tropomyosin and caldesmon domains. Biophys J 71:1920-33
Berry, M B; Meador, B; Bilderback, T et al. (1994) The closed conformation of a highly flexible protein: the structure of E. coli adenylate kinase with bound AMP and AMPPNP. Proteins 19:183-98
Zou, G; Phillips Jr, G N (1994) A cellular automaton model for the regulatory behavior of muscle thin filaments. Biophys J 67:11-28
Avila-Sakar, A J; Schmid, M F; Li, L S et al. (1993) Preliminary electron crystallographic analysis of ice-embedded tropomyosin crystals. J Struct Biol 110:67-74
Chacko, S; Phillips Jr, G N (1992) Diffuse x-ray scattering from tropomyosin crystals. Biophys J 61:1256-66

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