Structural studies of the airway surface liquid volume regulator human SPLUNC1 (2013)

Undergraduate: Herodes Guzman

Faculty Advisor: Matthew Redinbo
Department: Chemistry

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Structural studies of the short palate, lung, and nasal epithelial clone (SPLUNC1) K138E point mutation were conducted. The protein is found in the airway surface liquid (ASL) that covers the epithelial cells of mammalian airways and functions as a protease inhibitor blocking the activation of the epithelial sodium channel, ENaC. Careful regulation of ENaC by SPLUNC1 helps maintain adequate ASL volume and prevents the development of thick mucus and lung infection that plague cystic fibrosis (CF) patients. Malfunction of SPLUNC1 is speculated to contribute to these complications in CF. The K138E mutation was selected to observe any structural changes that could reveal why this mutant exhibited hyperactivity in a previous study. Purified mutant SPLUNC1 was obtained to perform crystal screening. Diffraction data from one harvested crystal gave 2.67 A resolution data. This data was used to formulate an electron density map for comparison with a previous wild-type SPLUNC1 structure. The SPLUNC1 K138E model is currently being examined for any differences it may have with the wild type model. In addition, circular dichroism (CD) will be used to determine whether a speculated salt bridge found at the 138-lysine residue plays a significant role in SPLUNC1 function. These studies on SPLUNC1 could reveal more about its role in regulating ALS via the inhibition of ENaC and could lead to improvements in the treatment of CF patients1