Our long term goal is to identify the physical mechanisms that regulate calcium resequestration by the Ca-ATPase in cardiac sarcoplasmic reticulum (SR) membranes. This active transport protein functions to modulate the rate and extent of myocardial relaxation in the heart. The regulatory protein phospholamban (PLB) is co-expressed with the Ca-ATPase in cardiac SR, and prior to beta-adrenergic stimulation functions to inhibit the transport activity of the Ca-ATPase. It is our hypothesis that the normal catalytic motions involved in the transport mechanism of the Ca-ATPase are modulated by either PLB or changes in membrane lipid composition, and that alterations in these regulatory mechanisms underlie heart disease. Therefore, a primary goal of the proposed research is the identification of structural changes that couple ATP hydrolysis to calcium transport, and how PLB and membrane composition modify catalytically important structural transitions. This will involve the use of spin-label EPR, optical and vibrational spectroscopies in conjunction with site-directed mutagenesis to probe protein structure at defined sites on the Ca-ATPase and on PLB. A second goal is the determination of structural features of PLB that permit the regulation of Ca-ATPase transport function. These measurements will aim to define sites of interaction between PLB and the Ca-ATPase, measure changes in PLB structure and binding to the Ca-ATPase, and to investigate the structural coupling between the cytosolic and transmembrane domains of PLB with respect to the modulation of Ca-ATPase function.
Our specific aims i nclude: (1) Identify dynamic structural changes of the Ca-ATPase important to calcium transport, (2) Define mechanisms of PLB regulation of Ca-ATPase transport function, (3) Determine structure of PLB involved in regulation of Ca-ATPase transport activity, and (4) Define mechanisms of phospholipid regulation of Ca-ATPase ion transport. The identification of the structural mechanisms underlying regulation of Ca-ATPase function will permit the design of effective therapies to alleviate the loss of cardiac function in the failing heart.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL064031-03
Application #
6652029
Study Section
Physical Biochemistry Study Section (PB)
Program Officer
Reinlib, Leslie
Project Start
2001-04-01
Project End
2005-04-30
Budget Start
2003-05-01
Budget End
2004-04-30
Support Year
3
Fiscal Year
2003
Total Cost
$478,625
Indirect Cost
Name
Battelle Pacific Northwest Laboratories
Department
Type
DUNS #
032987476
City
Richland
State
WA
Country
United States
Zip Code
99352
Chen, Linda T L; Yao, Qing; Soares, Thereza A et al. (2009) Phospholamban modulates the functional coupling between nucleotide domains in Ca-ATPase oligomeric complexes in cardiac sarcoplasmic reticulum. Biochemistry 48:2411-21
Chen, Baowei; Mahaney, James E; Mayer, M Uljana et al. (2008) Concerted but noncooperative activation of nucleotide and actuator domains of the Ca-ATPase upon calcium binding. Biochemistry 47:12448-56
Stenoien, David L; Knyushko, Tatyana V; Londono, Monica P et al. (2007) Cellular trafficking of phospholamban and formation of functional sarcoplasmic reticulum during myocyte differentiation. Am J Physiol Cell Physiol 292:C2084-94
Li, Jinhui; Boschek, Curt B; Xiong, Yijia et al. (2005) Essential role for Pro21 in phospholamban for optimal inhibition of the Ca-ATPase. Biochemistry 44:16181-91
Li, Jinhui; Bigelow, Diana J; Squier, Thomas C (2004) Conformational changes within the cytosolic portion of phospholamban upon release of Ca-ATPase inhibition. Biochemistry 43:3870-9
Li, Jinhui; Xiong, Yijia; Bigelow, Diana J et al. (2004) Phospholamban binds in a compact and ordered conformation to the Ca-ATPase. Biochemistry 43:455-63
Chen, Baowei; Squier, Thomas C; Bigelow, Diana J (2004) Calcium activation of the Ca-ATPase enhances conformational heterogeneity between nucleotide binding and phosphorylation domains. Biochemistry 43:4366-74
Li, Jinhui; Bigelow, Diana J; Squier, Thomas C (2003) Phosphorylation by cAMP-dependent protein kinase modulates the structural coupling between the transmembrane and cytosolic domains of phospholamban. Biochemistry 42:10674-82
Ferrington, Deborah A; Yao, Qing; Squier, Thomas C et al. (2002) Comparable levels of Ca-ATPase inhibition by phospholamban in slow-twitch skeletal and cardiac sarcoplasmic reticulum. Biochemistry 41:13289-96
Chen, Baowei; Bigelow, Diana J (2002) Phosphorylation induces a conformational transition near the lipid-water interface of phospholamban reconstituted with the Ca-ATPase. Biochemistry 41:13965-72

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