Comparing the structure and dynamics of phospholamban pentamer in its unphosphorylated and pseudo-phosphorylated states.
Human phospholamban (PLN), a 30 kDa homopentamer in the sarcoplasmic reticulum (SR) membrane, controls the magnitude of heart muscle contraction and relaxation by regulating the calcium pumping activity of the SR Ca(2+)-ATPase (SERCA). When PLN is not phosphorylated, it binds and inhibits SERCA. Phosphorylation of PLN at S16 or T17 releases such inhibitory effect. It remains a matter of debate whether phosphorylation perturbs the structure of PLN, which in turn affects its interaction with SERCA. Here we examine by NMR spectroscopy the structure and dynamics of PLN pentamer with a physiologically relevant, phosphorylation-mimicking mutation, S16E. Based on extensive NMR data, including NOEs, dipolar couplings, and solvent exchange of backbone amides, we conclude that the phosphorylation-mimicking mutation does not perturb the pentamer structure. However, (15)N R(1) and R(2) relaxation rates and (15)N((1)H) NOEs suggest subtle differences in the dynamics of the extramembrane portion of the protein.
Oxenoid
Kirill
K
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Rice
Amanda J
AJ
Chou
James J
JJ
D019943:Amino Acid Substitution; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008970:Molecular Weight; D019906:Nuclear Magnetic Resonance, Biomolecular; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D013329:Structure-Activity Relationship; D000099211:Phospholamban
D002135:Calcium-Binding Proteins; D011993:Recombinant Fusion Proteins; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D012694:Serine; D000099211:Phospholamban