1HQX

R308K ARGINASE VARIANT

Summary for 1HQX

• Entry DOI: 10.2210/pdb1hqx/pdb
• Related: 1RLA
• Descriptor: ARGINASE, MANGANESE (II) ION (3 entities in total)
• Functional Keywords: binuclear manganese cluster, mutagenesis, arginase, subunit-subunit interactions, hydrolase
• Biological source: Rattus norvegicus (Norway rat)
• Total number of polymer chains: 3
• Total formula weight: 105302.87

Authors

Lavulo, L.T.,Sossong Jr., T.M.,Brigham-Burke, M.R.,Doyle, M.L.,Cox, J.D.,Christianson, D.W.,Ash, D.E. (deposition date: 2000-12-20, release date: 2001-06-06, Last modification date: 2024-05-29)

Primary citation

Lavulo, L.T.,Sossong Jr., T.M.,Brigham-Burke, M.R.,Doyle, M.L.,Cox, J.D.,Christianson, D.W.,Ash, D.E.
Subunit-subunit interactions in trimeric arginase. Generation of active monomers by mutation of a single amino acid.
J.Biol.Chem., 276:14242-14248, 2001

PubMed 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.

PubMed: 11278703
DOI: 10.1074/jbc.M010575200

Experimental method

X-RAY DIFFRACTION (3 Å)