PDBsum entry 5eqa

Biosynthetic protein

PDB id: 5eqa

Contents

Protein chains

254 a.a.

Metals

_CL ×9

Waters ×1075

PDB id:

5eqa

Name:

Biosynthetic protein

Title:

Crystal structure of medicago truncatula histidinol-phosphate phosphatase (mthpp) with intermolecular cross-link between lys158 and cys245

Structure:

Inositol monophosphatase. Chain: a, b, c, d. Engineered: yes

Source:

Medicago truncatula. Barrel medic. Organism_taxid: 3880. Gene: mtr_3g117220. Expressed in: escherichia coli. Expression_system_taxid: 511693.

Resolution:

1.32Å R-factor: 0.125 R-free: 0.165

Authors:

M.Ruszkowski,Z.Dauter

Key ref:

M.Ruszkowski and Z.Dauter (2016). Structural Studies of Medicago truncatula Histidinol Phosphate Phosphatase from Inositol Monophosphatase Superfamily Reveal Details of Penultimate Step of Histidine Biosynthesis in Plants. J Biol Chem, 291, 9960-9973. PubMed id: 26994138 DOI: 10.1074/jbc.M115.708727

Date:

12-Nov-15 Release date: 30-Mar-16

Protein chains

G7J7Q5  (G7J7Q5_MEDTR) -  histidinol-phosphatase from Medicago truncatula

Seq: 326 a.a.

Struc: 254 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.3.1.3.15 - histidinol-phosphatase.
• Pathway: Histidine Biosynthesis (late stages)
• Reaction: L-histidinol phosphate + H2O = L-histidinol + phosphate

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

reference

DOI no: 10.1074/jbc.M115.708727

J Biol Chem 291:9960-9973 (2016)

PubMed id: 26994138

Structural Studies of Medicago truncatula Histidinol Phosphate Phosphatase from Inositol Monophosphatase Superfamily Reveal Details of Penultimate Step of Histidine Biosynthesis in Plants.

M.Ruszkowski, Z.Dauter.

ABSTRACT

The penultimate enzyme in the histidine biosynthetic pathway catalyzes dephosphorylation of l-histidinol 1-phosphate (HOLP) into l-histidinol. The recently discovered in Arabidopsis thaliana plant-type histidinol phosphate phosphatase (HPP) shares no homology with the two other HPP superfamilies known previously in prokaryotes and resembles myo-inositol monophosphatases (IMPases). In this work, identification of an HPP enzyme from a model legume, Medicago truncatula (MtHPP) was based on the highest sequence identity to A. thaliana enzyme. Biochemical assays confirmed that MtHPP was able to cleave inorganic phosphate from HOLP but not from d-myo-inositol-1-phosphate, the main substrate of IMPases. Dimers of MtHPP, determined by size exclusion chromatography, in the presence of CO2 or formaldehyde form mutual, methylene-bridged cross-links between Lys(158) and Cys(245) residues. Four high resolution crystal structures, namely complexes with HOLP (substrate), l-histidinol (product), and PO4 (3-) (by-product) as well as the structure showing the cross-linking between two MtHPP molecules, provide detailed structural information on the enzyme. Based on the crystal structures, the enzymatic reaction mechanism of IMPases is accustomed to fit the data for MtHPP. The enzymatic reaction, which requires Mg(2+) cations, is catalyzed mainly by amino acid residues from the N-terminal domain. The C-terminal domain, sharing little identity with IMPases, is responsible for the substrate specificity (i.e. allows the enzyme to distinguish between HOLP and d-myo-inositol-1-phosphate). Structural features, mainly the presence of a conserved Asp(246), allow MtHPP to bind HOLP specifically.