PDBsum entry 1t5t

Hydrolase

PDB id: 1t5t

Contents

Protein chain

994 a.a. *

Ligands

ALF

ADP

Metals

_CA ×2

_MG ×2

__K

Waters ×43

* Residue conservation analysis

PDB id:

1t5t

Name:

Hydrolase

Title:

Structure of the (sr)ca2+-atpase ca2-e1-adp:alf4- form

Structure:

Sarcoplasmic/endoplasmic reticulum calcium atpase 1 isoform serca1a. Chain: a. Synonym: calcium pump 1, serca1, sr ca(2+)-atpase 1, calcium- transporting atpase sarcoplasmic reticulum type, fast twitch skeletal muscle isoform, endoplasmic reticulum class 1/2 ca(2+) atpase. Ec: 3.6.3.8

Source:

Oryctolagus cuniculus. Rabbit. Organism_taxid: 9986

Resolution:

2.90Å R-factor: 0.247 R-free: 0.293

Authors:

T.L.-M.Sorensen,J.V.Moller,P.Nissen

Key ref:

T.L.Sørensen et al. (2004). Phosphoryl transfer and calcium ion occlusion in the calcium pump. Science, 304, 1672-1675. PubMed id: 15192230 DOI: 10.1126/science.1099366

Date:

05-May-04 Release date: 15-Jun-04

Protein chain

P04191  (AT2A1_RABIT) -  Sarcoplasmic/endoplasmic reticulum calcium ATPase 1 from Oryctolagus cuniculus

Seq: 1001 a.a.

Struc: 994 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.7.2.2.10 - P-type Ca(2+) transporter.
• Reaction: Ca²⁺(in) + ATP + H2O = Ca²⁺(out) + ADP + phosphate + H⁺

Ca(2+)(in) + ATP + H2O = Ca(2+)(out) (Bound ligand (Het Group name = ADP) corresponds exactly) + ADP + phosphate + H(+)

• Cofactor: Mg(2+)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1126/science.1099366

Science 304:1672-1675 (2004)

PubMed id: 15192230

Phosphoryl transfer and calcium ion occlusion in the calcium pump.

T.L.Sørensen, J.V.Møller, P.Nissen.

ABSTRACT

A tight coupling between adenosine triphosphate (ATP) hydrolysis and vectorial ion transport has to be maintained by ATP-consuming ion pumps. We report two crystal structures of Ca2+-bound sarco(endo)plasmic reticulum Ca2+-adenosine triphosphatase (SERCA) at 2.6 and 2.9 angstrom resolution in complex with (i) a nonhydrolyzable ATP analog [adenosine (beta-gamma methylene)-triphosphate] and (ii) adenosine diphosphate plus aluminum fluoride. SERCA reacts with ATP by an associative mechanism mediated by two Mg2+ ions to form an aspartyl-phosphorylated intermediate state (Ca2-E1 approximately P). The conformational changes that accompany the reaction with ATP pull the transmembrane helices 1 and 2 and close a cytosolic entrance for Ca2+, thereby preventing backflow before Ca2+ is released on the other side of the membrane.

Selected figure(s)

Figure 2.
Fig. 2. Conformational changes upon nucleotide binding. Comparison of the Ca[2]-E[1] and Ca[2]-E[1]-AMPPCP forms, based on the same alignment as in Fig. 1C. Domains occupying similar positions are shown as colored surfaces with the coordination spheres of the two calcium ions in blue. The series of conformational changes leading from ATP binding to Ca^2+ occlusion have been indicated by arrows on the Ca[2]-E[1] form. The figure was prepared with PyMOL (26).

Figure 3.
Fig. 3. The Mg2+-catalyzed phosphoryl transferase activity. (A) Overview of Mg: AMPPCP binding, shown with a ball-and-stick representation of interacting residues. The color scheme is the same as in Fig. 1C. The bent conformation of the nucleotide, stabilized primarily by three arginines, can be seen. (B) Coordination of the -phosphate and Asp351 by a magnesium ion. The Asp351 side chain is still far from the -phosphorus atom. (C) The transition state of phosphoryl transfer as mimicked by ADP:AlF[4]^-. The Mg2+ ion coordinates Asp351 and AlF[4]^-, and the ß-phosphate and the Asp351 side chain form tight coordination of the aluminum atom as indicated by dashed lines in color. Residues important for stabilization are indicated.

The above figures are reprinted by permission from the AAAs: Science (2004, 304, 1672-1675) copyright 2004.

Figures were selected by an automated process.