| Autor: |
de Paiva FCR; Department of Microbiology, Institute of Biomedical Sciences II, University of São Paulo, São Paulo, Brazil., Chan K; Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom., Samborskyy M; Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom., Silber AM; LaBTryps - Laboratory of Biochemistry of Tryps, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil., Leadlay PF; Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom., Dias MVB; Department of Microbiology, Institute of Biomedical Sciences II, University of São Paulo, São Paulo, Brazil. |
| Abstrakt: |
Adenylate-forming enzymes (AFEs) are a mechanistic superfamily of proteins that are involved in many cellular roles. In the biosynthesis of benzoxazole antibiotics, an AFE has been reported to play a key role in the condensation of cyclic molecules. In the biosynthetic gene cluster for the benzoxazole AJI9561, AjiA1 catalyzes the condensation of two 3-hydroxyanthranilic acid (3-HAA) molecules using ATP as a co-substrate. Here, the enzymatic activity of AjiA1 is reported together with a structural analysis of its apo form. The structure of AjiA1 was solved at 2.0 Å resolution and shows a conserved fold with other AFE family members. AjiA1 exhibits activity in the presence of 3-HAA (K m = 77.86 ± 28.36, k cat = 0.04 ± 0.004) and also with the alternative substrate 3-hydroxybenzoic acid (3-HBA; K m = 22.12 ± 31.35, k cat = 0.08 ± 0.005). The structure of AjiA1 in the apo form also reveals crucial conformational changes that occur during the catalytic cycle of this enzyme which have not been described for any other AFE member. Consequently, the results shown here provide insights into this protein family and a new subgroup is proposed for enzymes that are involved in benzoxazole-ring formation. |
