Nereis sarcoplasmic Ca2+-binding protein has a highly unstructured apo state which is switched to the native state upon binding of the first Ca2+ ion.
NSCP, a sarcoplasmic Ca2+/Mg2+-binding protein from Nereis diversicolor, shows an allosteric change during Ca2+ binding and a high positive cooperativity for Mg2+ binding. Here we report the results of CD and NMR experiments aiming to characterize the apo state and the Ca2+-induced conformational changes in this protein. Circular dichroism spectra of the apo form are indicative of a reduced helical structure. In contrast, NMR spectra show no element of regular secondary or tertiary structure. Addition of one Ca2+ determines large spectral changes bringing the molecule in a conformation which is very close to the native three Ca2+ state. Addition of the second and third Ca2+ shifts this equilibrium progressively towards the liganded conformation but affects only minimally the spectrum of the liganded species.
Prêcheur
B
B
Institut National de la Santé et de la Recherche Médicale, Institut Curie, Orsay, France.
Cox
J A
JA
Petrova
T
T
Mispelter
J
J
Craescu
C T
CT
D000818:Animals; D001059:Apoproteins / Q000737:chemistry* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D002942:Circular Dichroism; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D018482:Muscle, Skeletal / Q000737:chemistry; D011077:Polychaeta / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation
D001059:Apoproteins; D002135:Calcium-Binding Proteins; D008024:Ligands; D002118:Calcium