Phospholamban thiols play a central role in activation of the cardiac muscle sarcoplasmic reticulum calcium pump by nitroxyl.
Nitroxyl (HNO) donated by Angeli's salt activates uptake of Ca(2+) by the cardiac SR Ca(2+) pump (SERCA2a). To determine whether HNO achieves this by a direct interaction with SERCA2a or its regulatory protein, phospholamban (PLN), we measured its effects on SERCA2a activation (as reflected in dephosphorylation) using insect cell microsomes expressing SERCA2a with or without PLN (wild-type and Cys --> Ala mutant). The results show that activation of SERCA2a dephosphorylation by HNO is PLN-dependent and that PLN thiols are targets for HNO. We conclude that HNO produces a disulfide bond that alters the conformation of PLN, relieving inhibition of the Ca(2+) pump.
Froehlich
Jeffrey P
JP
Department of Medicine, Johns Hopkins University, Baltimore, Maryland 21205, USA. jfroehl3@jhmi.edu
Mahaney
James E
JE
Keceli
Gizem
G
Pavlos
Christopher M
CM
Goldstein
Russell
R
Redwood
Abiona J
AJ
Sumbilla
Carlota
C
Lee
Dong I
DI
Tocchetti
Carlo G
CG
Kass
David A
DA
Paolocci
Nazareno
N
Toscano
John P
JP
D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000502:physiology*; D004285:Dogs; D004789:Enzyme Activation / Q000502:physiology; D005609:Free Radicals / Q000737:chemistry / Q000378:metabolism; D007313:Insecta; D008861:Microsomes / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology*; D009589:Nitrogen Oxides / Q000737:chemistry* / Q000378:metabolism; D010766:Phosphorylation; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000502:physiology*; D000099211:Phospholamban
D000975:Antioxidants; D002135:Calcium-Binding Proteins; D005609:Free Radicals; D009589:Nitrogen Oxides; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D013438:Sulfhydryl Compounds; D000099211:Phospholamban; C039900:nitroxyl