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Title: Structural studies of smooth muscle caldesmon
Author: Fertig, Tudor Emanuel
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2012
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Caldesmons are a family of proteins that bind actin with high affinity as well as myosin, tropomyosin and ca1modulin. Although the two described isoform subfamilies (smooth muscle and non-muscle caldesmons) have highly conserved functional domains, the smooth muscle isoforms contain an additional central region, which encloses a 168 residue single alpha helix domain (SAH). Smooth muscle caldesmons (hCaD) are found exclusively in smooth muscle cells, and are speculated to have a direct role in the regulation of muscle contraction, although the exact details of the molecular interactions are unclear. By contrast, non-muscle isoforms (lCaD) are found in almost all cell types and are involved in cytoskeletal formation and cell trafficking. The aim of this research was to investigate the structure of hCaD, to help understand how it may influence actomyosin function. This was done using a multiplicity of methods, some of which were not previously used for caldesmon studies. Firstly, metal shadowing electron microscopy and atomic force microscopy were used to determine the shape and flexibility of tissue purified turkey gizzard hCaD. The data revealed variations in shape and discrepancies in length between molecules prepared under regular conditions and the ones prepared under the stress of surface tension forces. Secondly, sequence analysis and circular dichroism were employed to study heaD secondary structure. The data indicated a new model for the organization of the heaD molecule, based on the presence of numerous SAH motifs, in all domains. Finally, caldesmon mutants with missing or extended central SAH motifs were constructed, in order to study the involvement of the SAH domain in smooth muscle contraction. Here, the expression and purification of these constructs in the baculovirus system was characterized.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available