PDBsum entry 1hqx

Hydrolase

PDB id: 1hqx

Contents

Protein chains

314 a.a. *

Metals

_MN ×6

Waters ×29

* Residue conservation analysis

PDB id:

1hqx

Name:

Hydrolase

Title:

R308k arginase variant

Structure:

Arginase. Chain: a, b, c. Engineered: yes. Mutation: yes

Source:

Rattus norvegicus. Norway rat. Organism_taxid: 10116. Expressed in: escherichia coli. Expression_system_taxid: 562

Biol. unit:

Trimer (from PQS)

Resolution:

3.00Å R-factor: 0.263 R-free: 0.296

Authors:

L.T.Lavulo,T.M.Sossong Jr.,M.R.Brigham-Burke,M.L.Doyle,J.D.Cox, D.W.Christianson,D.E.Ash

Key ref:

L.T.Lavulo et al. (2001). Subunit-subunit interactions in trimeric arginase. Generation of active monomers by mutation of a single amino acid. J Biol Chem, 276, 14242-14248. PubMed id: 11278703 DOI: 10.1074/jbc.M010575200

Date:

20-Dec-00 Release date: 06-Jun-01

Protein chains

P07824  (ARGI1_RAT) -  Arginase-1 from Rattus norvegicus

Seq: 323 a.a.

Struc: 314 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.3.5.3.1 - arginase.
• Pathway: Urea Cycle and Arginine Biosynthesis
• Reaction: L-arginine + H2O = urea + L-ornithine
• Cofactor: Mn(2+)

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

reference

DOI no: 10.1074/jbc.M010575200

J Biol Chem 276:14242-14248 (2001)

PubMed id: 11278703

Subunit-subunit interactions in trimeric arginase. Generation of active monomers by mutation of a single amino acid.

L.T.Lavulo, T.M.Sossong, M.R.Brigham-Burke, M.L.Doyle, J.D.Cox, D.W.Christianson, D.E.Ash.

ABSTRACT

The structure of the trimeric, manganese metalloenzyme, rat liver arginase, has been previously determined at 2.1-A resolution (Kanyo, Z. F., Scolnick, L. R., Ash, D. E., and Christianson, D. W., (1996) Nature 383, 554-557). A key feature of this structure is a novel S-shaped oligomerization motif at the carboxyl terminus of the protein that mediates approximately 54% of the intermonomer contacts. Arg-308, located within this oligomerization motif, nucleates a series of intramonomer and intermonomer salt links. In contrast to the trimeric wild-type enzyme, the R308A, R308E, and R308K variants of arginase exist as monomeric species, as determined by gel filtration and analytical ultracentrifugation, indicating that mutation of Arg-308 shifts the equilibrium for trimer dissociation by at least a factor of 10(5). These monomeric arginase variants are catalytically active, with k(cat)/K(m) values that are 13-17% of the value for wild-type enzyme. The arginase variants are characterized by decreased temperature stability relative to the wild-type enzyme. Differential scanning calorimetry shows that the midpoint temperature for unfolding of the Arg-308 variants is in the range of 63.6-65.5 degrees C, while the corresponding value for the wild-type enzyme is 70 degrees C. The three-dimensional structure of the R308K variant has been determined at 3-A resolution. At the high protein concentrations utilized in the crystallizations, this variant exists as a trimer, but weakened salt link interactions are observed for Lys-308.

Selected figure(s)

Figure 1.
Fig. 1. The crystal structure of rat liver arginase showing the trimeric quarternary structure, S-shaped tail in white at the subunit interface, and two manganese ions (spheres) at the active site of each subunit. Arg-308 is represented in the white ball and stick form.

Figure 4.
Fig. 4. Differential scanning calorimetry data for the unfolding of wild-type arginase (solid line), R308A (dashed and dotted line), R308E (dotted line), and R308K (dashed line) shown as excess molar heat capacity versus temperature. All scans are normalized per mole of arginase subunit. Conditions were as follows: 20 mM NaPO[4], 150 mM NaCl, 0.1 mM MnCl[2], pH 7.4, and 0.4 mg/ml arginase.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2001, 276, 14242-14248) copyright 2001.

Figures were selected by an automated process.