REU: Calmodulin Mediated Disorder-to-order Transitions: Calcineurin as a Model System - Supplemental

Participants Selected Two participants have already been selected: Ms. Anne (Annie) E. Jensen and Ms. Meghan S. Hamilton. Each of these participants are currently undergraduates and will remain in that status at the end of their REU experiences with the P1. Both participants are U.S. citizens. Annie has previously worked in the P1's laboratory. She was home-schooled in Lexington, Kentucky, and was considering pursuing a college degree in science. Annie worked in the P1's laboratory on a voluntary basis through the Fall of 2007 and Spring of 2008 in order to gain laboratory experience. The P1 offered Annie a paid Summer position in 2008 before she left for Harvey Mudd College in Fall 2008. Annie would benefit significantly from an additional Summer of research now that she has completed some college-level science courses. Meghan has been pursuing research for credit in the P1's laboratory through the Spring 2009 semester. She plans to attend graduate school when she graduates from the University of Kentucky. Meghan has only been able to spend a few hours each week in the laboratory and would benefit greatly from a more concentrated research experience over the Summer. Form and Nature of Each Students Involvement 1) Conformational properties of the regulatory domain of calcineurin Calcineurin (CaN) is a ubiquitously-expressed, highly conserved SerlThr phosphatase whose activity is regulated by calmodulin (CaM). When cellular calcium levels are low CaN is maintained in an inactive state by its own autoinhibitory domain (AID; Figure la). CaM binds calcium when the levels rise, and subsequently binds CaN releasing the AID, leading to CaN activation. The CaM binding region in CaN is located within a 152 regulatory domain which includes the AID and a 31 residue C- terminal tail (CT). Experimental evidence suggests that this regulatory domain is largely disordered in the CaN inactive state. The P1's laboratory has expressed the regulatory domain of CaN as an isolated fragment (called RD-AID-CT). Preliminary circular dichroism (CD) spectroscopy data indicates that the RD-AID-CT fragment is largely disordered in the absence of CaM (Figure 1 b). Upon CaM binding the RD-AID-CT becomes -`90% cx- helical indicating that this fragment undergoes a disorder- to-order transition (Figure 1 b). Annie will extend our studies using a combination of CD spectroscopy and fluorimetry. Annie will investigate the conformational properties of the RD-AID-CT fragment (sans CaM) under a variety of solution conditions including in the presence of crowding agents. The specific question she will pursue is whether the RD-AID-CT fragment is disordered under conditions that model the intracellular milieu. This project a. b. 20 230 Wavelength nm igure 1: a. CaN structure with the lisordered regulatory domain indicated. b. CD spectra for the RD- ~.ID-CT fragment (blue), CaM (red), `md the RD-AID-CT:CaM complex purple). The grey spectrum is the iiathematical sum of the RD-AID-CT `md CaM spectra. is of direct relevance to the P1's funded proposal