Recombinant Expression and Functional Assessment of Uricase from a Pertinent Origin of the Enzyme, Streptomyces sp. Strain 17-1.

Background: Uricase or urate oxidase, as a therapeutic enzyme, is extensively applied to oxidize accumulated uric acid in the body to soluble form to treat related illnesses.

Objectives: This study was conducted with the aim of searching for potential sources of uricase-producing Streptomyces from Eshtehard salt desert in Alborz province, Iran and heterologous expression, purification and functional assay of the enzyme.

Materials and methods: Main screening was conducted by cultivation of the strains on a medium enriched with 0.3 percent (w/v) uric acid. The uricase gene from the most potent strain was then recombinantly expressed in E. coli BL21 (DL3).

Results: Out of the tested strains, only seven showed uricase activity. The highest level of native uricase activity (11.5735 U.mL^-1) belonged to strain 17-1, which had the closest similarity to Streptomyces nigra. A recombinant uricase with a molecular mass of approximately 38 kDa was produced. The purified uricase exhibited a specific activity of about 28.29±0.59 U.mg^-1, which is among the highest level of uricase activity reported by other studies.

Conclusions: This enzyme is a promising candidate for further applicable investigations and large-scale production in terms of its large volume of soluble expression and selective competitive activity.