1I6T

STRUCTURE OF INORGANIC PYROPHOSPHATASE

Summary for 1I6T

• Entry DOI: 10.2210/pdb1i6t/pdb
• Descriptor: INORGANIC PYROPHOSPHATASE, CALCIUM ION, SODIUM ION, ... (6 entities in total)
• Functional Keywords: hydrolase, inorganic pyrophosphatase
• Biological source: Escherichia coli
• Cellular location: Cytoplasm : P0A7A9
• Total number of polymer chains: 1
• Total formula weight: 20050.90

Authors

Samygina, V.R.,Popov, A.N.,Lamzin, V.S.,Avaeva, S.M. (deposition date: 2001-03-05, release date: 2001-12-05, Last modification date: 2023-08-09)

Primary citation

Samygina, V.R.,Popov, A.N.,Rodina, E.V.,Vorobyeva, N.N.,Lamzin, V.S.,Polyakov, K.M.,Kurilova, S.A.,Nazarova, T.I.,Avaeva, S.M.
The structures of Escherichia coli inorganic pyrophosphatase complexed with Ca(2+) or CaPP(i) at atomic resolution and their mechanistic implications.
J.Mol.Biol., 314:633-645, 2001

PubMed Abstract: Two structures of Escherichia coli soluble inorganic pyrophosphatase (EPPase) complexed with calcium pyrophosphate (CaPP(i)-EPPase) and with Ca(2+) (Ca(2+)-EPPase) have been solved at 1.2 and 1.1 A resolution, respectively. In the presence of Mg(2+), this enzyme cleaves pyrophosphate (PP(i)) into two molecules of orthophosphate (P(i)). This work has enabled us to locate PP(i) in the active site of the inorganic pyrophosphatases family in the presence of Ca(2+), which is an inhibitor of EPPase.Upon PP(i) binding, two Ca(2+) at M1 and M2 subsites move closer together and one of the liganded water molecules becomes bridging. The mutual location of PP(i) and the bridging water molecule in the presence of inhibitor cation is catalytically incompetent. To make a favourable PP(i) attack by this water molecule, modelling of a possible hydrolysable conformation of PP(i) in the CaPP(i)-EPPase active site has been performed. The reasons for Ca(2+) being the strong PPase inhibitor and the role in catalysis of each of four metal ions are the mechanistic aspects discussed on the basis of the structures described.

PubMed: 11846572
DOI: 10.1006/jmbi.2001.5149

Experimental method

X-RAY DIFFRACTION (1.2 Å)