Showcase of Undergraduate Research and Creative Endeavors (SOURCE)

Progress Toward Understanding Cadmium Inhibition of Troponin Function

Muscle contraction is a complicated mechanism that involves different protein complexes working synergistically to carry out and regulate the process. One such protein is the troponin complex, which serves as the link between brain signaling and muscle function. This protein is composed of three subunits: troponin-T, troponin-I, and troponin-C. Troponin-T anchors the rest of the complex to tropomyosin, a component of the muscle fiber. Troponin-I is responsible for inhibiting muscle contraction until a surge of calcium is recognized by troponin-C in response to a signal from the brain. Cadmium is a dangerous heavy metal that has carcinogenic properties and is known to impact cardiovascular function. Interestingly, cadmium can bind to troponin-C with equal or higher affinity than calcium. The aim of our research is to understand the impacts of cadmium on troponin function and its implications for muscle contraction. To date, we have encountered issues with troponin-I solubility, so we have adjusted our approach in that regard, working with smaller, more soluble regions of troponin-I that have strong interactions with troponin-C. Our current efforts are focused on cloning and purifying specific segments of troponin-I. We utilized PCR to modify and amplify the target region of the troponin-I gene. The KLD enzyme mix (NEB Biolabs) was used to phosphorylate and circularize the PCR product and degrade the residual template. We use the product from the KLD reactions to transform E. coli cells with our desired traits so we can begin testing the truncated troponin-I protein.