期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 117, 期 31, 页码 18448-18458出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.2006027117
关键词
ion pump; SERCA; ATP binding; phosphoryl transfer
资金
- SPring-8 [2016A0133, 2018A0144]
- Japan Society for the Promotion of Science KAKENHI [JP16H02499, JP19H00975]
Under physiological conditions, most Ca2+-ATPase (SERCA) molecules bind ATP before binding the Ca2+ transported. SERCA has a high affinity for ATP even in the absence of Ca2+, and ATP accelerates Ca2+ binding at pH values lower than 7, where SERCA is in the E2 state with low-affinity Ca2+-binding sites. Here we describe the crystal structure of SERCA2a, the isoform predominant in cardiac muscle, in the E2 center dot ATP state at 3.0-angstrom resolution. In the crystal structure, the arrangement of the cytoplasmic domains is distinctly different from that in canonical E2. The A-domain now takes an E1 position, and the N-domain occupies exactly the same position as that in the E1 center dot ATP center dot 2Ca(2+) state relative to the P-domain. As a result, ATP is properly delivered to the phosphorylation site. Yet phosphoryl transfer never takes place without the filling of the two transmembrane Ca2+-binding sites. The present crystal structure explains what ATP binding itself does to SERCA and how nonproductive phosphorylation is prevented in E2.
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