Tissue-specific interactions of TNI isoforms with other TN subunits and tropomyosins in C. elegans: The role of the C- and N-terminal extensions

The aim of this study is to investigate the function of the C-terminal extension of three troponin I isoforms, that are unique to the body wall muscles of Caenorhabditis elegans and to understand the molecular interactions within the TN complex between troponin I with troponin C/T, and tropomyosin. We constructed several expression vectors to generate recombinant proteins of three body wall and one pharyngeal troponin I isoforms in Escherichia coli. Protein overlay assays and Western blot analyses were performed using antibodies. We demonstrated that pharyngeal TNI-4 interacted with only the pharyngeal isoforms of troponin C/T and tropomyosin. In contrast, the body wall TNI-2 bound both the body wall and pharyngeal isoforms of these components. Similar to other invertebrates, the N-terminus of troponin I contributes to interactions with troponin C. Full-length troponin I was essential for interactions with tropomyosin isoforms. Deletion of the C-terminal extension had no direct effect on the binding of the body wall troponin I to other muscle thin filament troponin C/T and tropomyosin isoforms.

Published with permission from the copyright holder. This is a author's copy,as published in Biochimica Biophysica et Acta, April 2007, volume 1774, issue 4, pp456-465.
Publisher URL: http://dx.doi.org/10.1016/j.bbapap.2007.01.003
Copyright © 2007 Elsevier B. V. All rights reserved.