Structures of the Ca2+-ATPase complexes with ATP, AMPPCP and AMPPNP. An FTIR study.
We studied binding of ATP and of the ATP analogs adenosine 5'-(beta,gamma-methylene)triphosphate (AMPCP) and beta,gamma-imidoadenosine 5'-triphosphate (AMPPNP) to the Ca(2+)-ATPase of the sarcoplasmic reticulum membrane (SERCA1a) with time-resolved infrared spectroscopy. In our experiments, ATP reacted with ATPase which had AMPPCP or AMPPNP bound. These experiments monitored exchange of ATP analog by ATP and phosphorylation to the first phosphoenzyme intermediate Ca(2)E1P. These reactions were triggered by the release of ATP from caged ATP. Only small differences in infrared absorption were observed between the ATP complex and the complexes with AMPPCP and AMPPNP indicating that overall the interactions between nucleotide and ATPase are similar and that all complexes adopt a closed conformation. The spectral differences between ATP and AMPPCP complex were more pronounced at high Ca(2+) concentration (10 mM). They are likely due to a different position of the gamma-phosphate which affects the beta-sheet in the P domain.
Krasteva
Maria
M
Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden.
Barth
Andreas
A
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000737:chemistry*; D000266:Adenylyl Imidodiphosphate / Q000737:chemistry*; D000252:Calcium-Transporting ATPases / Q000737:chemistry*; D015394:Molecular Structure; D011485:Protein Binding; D012519:Sarcoplasmic Reticulum / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
D000266:Adenylyl Imidodiphosphate; C005147:5'-adenylyl (beta,gamma-methylene)diphosphonate; D000255:Adenosine Triphosphate; D000252:Calcium-Transporting ATPases