PDBsum entry 3it3

Hydrolase

PDB id: 3it3

Contents

Protein chains

337 a.a. *

Ligands

3AM ×2

Waters ×580

* Residue conservation analysis

PDB id:

3it3

Name:

Hydrolase

Title:

Crystal structure francisella tularensis histidine acid phosphatase d261a mutant complexed with substrate 3'-amp

Structure:

Acid phosphatase. Chain: a, b. Fragment: unp residues 17-351. Synonym: histidine acid phosphatase. Engineered: yes. Mutation: yes

Source:

Francisella tularensis subsp. Holarctica. Organism_taxid: 376619. Strain: lvs. Gene: ftl_0031. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.50Å R-factor: 0.172 R-free: 0.187

Authors:

H.Singh,R.L.Felts,T.J.Reilly,J.J.Tanner

Key ref:

H.Singh et al. (2009). Crystal Structures of the histidine acid phosphatase from Francisella tularensis provide insight into substrate recognition. J Mol Biol, 394, 893-904. PubMed id: 19836403 DOI: 10.1016/j.jmb.2009.10.009

Date:

27-Aug-09 Release date: 10-Nov-09

Protein chains

Q2A612  (Q2A612_FRATH) -

Enzyme reactions

• Enzyme class: E.C.3.1.3.2 - acid phosphatase.
• Reaction: a phosphate monoester + H2O = an alcohol + phosphate

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

reference

DOI no: 10.1016/j.jmb.2009.10.009

J Mol Biol 394:893-904 (2009)

PubMed id: 19836403

Crystal Structures of the histidine acid phosphatase from Francisella tularensis provide insight into substrate recognition.

H.Singh, R.L.Felts, J.P.Schuermann, T.J.Reilly, J.J.Tanner.

ABSTRACT

Histidine acid phosphatases catalyze the transfer of a phosphoryl group from phosphomonoesters to water at acidic pH using an active-site histidine. The histidine acid phosphatase from the category A pathogen Francisella tularensis (FtHAP) has been implicated in intramacrophage survival and virulence, motivating interest in understanding the structure and mechanism of this enzyme. Here, we report a structure-based study of ligand recognition by FtHAP. The 1.70-A-resolution structure of FtHAP complexed with the competitive inhibitor l(+)-tartrate was solved using single-wavelength anomalous diffraction phasing. Structures of the ligand-free enzyme and the complex with inorganic phosphate were determined at resolutions of 1.85 and 1.70 A, respectively. The structure of the Asp261Ala mutant enzyme complexed with the substrate 3'-AMP was determined at 1.50 A resolution to gain insight into substrate recognition. FtHAP exhibits a two-domain fold similar to that of human prostatic acid phosphatase, consisting of an alpha/beta core domain and a smaller domain that caps the core domain. The structures show that the core domain supplies the phosphoryl binding site, catalytic histidine (His17), and an aspartic acid residue (Asp261) that protonates the leaving group, while the cap domain contributes residues that enforce substrate preference. FtHAP and human prostatic acid phosphatase differ in the orientation of the crucial first helix of the cap domain, implying differences in the substrate preferences of the two enzymes. 3'-AMP binds in one end of a 15-A-long tunnel, with the adenine clamped between Phe23 and Tyr135, and the ribose 2'-hydroxyl interacting with Gln132. The importance of the clamp is confirmed with site-directed mutagenesis; mutation of Phe23 and Tyr135 individually to Ala increases K(m) by factors of 7 and 10, respectively. The structural data are consistent with a role for FtHAP in scavenging phosphate from small molecules present in host macrophage cells.

Selected figure(s)

Figure 1.
Fig. 1. Overall fold of FtHAP. (a) Ribbon drawing of the FtHAP protomer. Residues are colored according to a rainbow scheme, with blue at the N-terminus and red at the C-terminus. The P[i] ligand is shown in spheres. The side chains of His17, Phe23, and Tyr135 are drawn as sticks in white. Strands of the β-sheet are numbered. The first three helices of the polypeptide chain are labeled α1, α2, and α3. The conserved portion of the dimerization loop (residues 116–121) is colored magenta. (b) Ribbon and surface representations of the protomer, highlighting domain structure. The orientation is the same as in (a). The core domain is colored blue, and the cap domain is colored pink. The P[i] ligand is shown in spheres, and the side chains of His17, Phe23, and Tyr135 are drawn as sticks.

Figure 5.
Fig. 5. Cutaway view of the substrate-binding tunnel with bound 3′-AMP.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2009, 394, 893-904) copyright 2009.

Figures were selected by the author.