| First Author | Lavulo LT | Year | 2001 |
| Journal | J Biol Chem | Volume | 276 |
| Issue | 17 | Pages | 14242-8 |
| PubMed ID | 11278703 | Mgi Jnum | J:68999 |
| Mgi Id | MGI:1933886 | Doi | 10.1074/jbc.M010575200 |
| Citation | Lavulo LT, et al. (2001) Subunit-subunit interactions in trimeric arginase. Generation of active monomers by mutation of a single amino acid. J Biol Chem 276(17):14242-8 |
| abstractText | 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. |
