Molecular characterization of a highly efficient and thermostable phosphoribosyl anthranilate isomerase from...

Phosphoribosyl anthranilate isomerase is involved in the isomerization of phosphoribosyl anthranilate to 1-(o-carboxyphenylamino)-1-deoxyribulose 5-phosphate. In the present study, trpF_Gt, a gene encoding phosphoribosyl anthranilate isomerase from Geobacillus thermopakistaniensis, was cloned and expressed in Escherichia coli. The gene product, TrpF_Gt, was produced in E. coli in soluble and active form. Molecular characterization revealed that recombinant TrpF_Gt was highly efficient and stable. The apparent V_max and K_m values were 480 μmol min^-1 mg^-1 and 1.15 μM, respectively. The half-life of the enzyme was 90 min at 60 °C. Apart from thermostability, TrpF_Gt was highly stable against protein denaturants such as urea. There was no significant change in activity even after treatment with 8 M urea. To the best of our knowledge, TrpF_Gt, is the most active and stable phosphoribosyl anthranilate isomerase characterized to date and this is the first characterization of TrpF from the genus Geobacillus.