PDBsum entry 1kfq

Isomerase

PDB id: 1kfq

Contents

Protein chains

571 a.a. *

Metals

_CA ×2

Waters ×56

* Residue conservation analysis

PDB id:

1kfq

Name:

Isomerase

Title:

Crystal structure of exocytosis-sensitive phosphoprotein, pp63/parafusin (phosphoglucomutse) from paramecium. Open form

Structure:

Phosphoglucomutase 1. Chain: a, b. Engineered: yes

Source:

Paramecium tetraurelia. Organism_taxid: 5888. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.40Å R-factor: 0.233 R-free: 0.284

Authors:

S.Mueller,K.Diederichs,J.Breed,R.Kissmehl,K.Hauser,H.Plattner,W.Welte

Key ref:

S.Müller et al. (2002). Crystal structure analysis of the exocytosis-sensitive phosphoprotein, pp63/parafusin (phosphoglucomutase), from Paramecium reveals significant conformational variability. J Mol Biol, 315, 141-153. PubMed id: 11779235 DOI: 10.1006/jmbi.2001.5168

Date:

22-Nov-01 Release date: 16-Jan-02

Protein chains

P47244  (PGM1_PARTE) -  Phosphoglucomutase-1 from Paramecium tetraurelia

Seq: 572 a.a.

Struc: 571 a.a.

Enzyme reactions

• Enzyme class: E.C.5.4.2.2 - phosphoglucomutase (alpha-D-glucose-1,6-bisphosphate-dependent).
• Pathway: UDP-glucose, UDP-galactose and UDP-glucuronate Biosynthesis
• Reaction: alpha-D-glucose 1-phosphate = alpha-D-glucose 6-phosphate

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

Added reference

DOI no: 10.1006/jmbi.2001.5168

J Mol Biol 315:141-153 (2002)

PubMed id: 11779235

Crystal structure analysis of the exocytosis-sensitive phosphoprotein, pp63/parafusin (phosphoglucomutase), from Paramecium reveals significant conformational variability.

S.Müller, K.Diederichs, J.Breed, R.Kissmehl, K.Hauser, H.Plattner, W.Welte.

ABSTRACT

During exocytosis of dense-core secretory vesicles (trichocysts) in Paramecium, the protein pp63/parafusin (pp63/pf) is transiently dephosphorylated. We report here the structures of two crystal forms of one isoform of this protein which has a high degree of homology with rabbit phosphoglucomutase, whose structure has been reported. As expected, both proteins possess highly similar structures, showing the same four domains forming two lobes with an active-site crevice in between. The two X-ray structures that we report here were determined after crystallization in the presence of sulfate and tartrate, and show the lobes arranged as a closed and an open conformation, respectively. While both conformations possess a bound divalent cation, only the closed (sulfate-bound) conformation shows bound sulfate ions in the "phosphate-transfer site" near the catalytic serine residue and in the "phosphate-binding site". Comparison with the open form shows that the latter dianion is placed in the centre of three arginine residues, one contributed by subunit II and two by subunit IV, suggesting that it causes a contraction of the arginine triangle, which establishes the observed conformational closure of the lobes. It is therefore likely that the closed conformation forms only when a phosphoryl group is bound to the phosphate-binding site. The previously published structure of rabbit phosphoglucomutase is intermediate between these two conformers. Several of the known reversible phosphorylation sites of pp63/pf-1 are at positions critical for transition between the conformations and for binding of the ligands and thus give hints as to possible roles of pp63/pf-1 in the course of exocytosis.

Selected figure(s)

Figure 1.
Figure 1. Structure of pp63/pf-sulfate and structural alignment with rabbit PGM. Important secondary structure elements and loops are labelled according to Liu et al[15]. In all subsequent Figures and Tables the domains are coded in the same colours as in (a). (a) Structure of the monomer in ribbon representation. The molecule is oriented to show the bilobal shape with the large lobe to the left and the small lobe to the right, and the approximate dimensions indicated in Å. Domains I, II, III, IV are coloured green, blue, red and yellow, respectively. The divalent cation and the two sulfate molecules are indicated as ball and stick models. (b) Structural alignment of pp63/pf-sulfate with PGM. This and all further structural Figures were prepared with MOLSCRIPT[49].

Figure 3.
Figure 3. (a) The pp63/pf-tartrate and (b) the pp63/pf-sulfate structures in ribbon representation. The stereo views show the C^a carbon trace. Critical residues of the active site, the latch segment, loop A segment and others discussed in the text are shown and labelled.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2002, 315, 141-153) copyright 2002.

Figures were selected by an automated process.