RESUMO
During the last decade the number of characterized F420-dependent enzymes has significantly increased. Many of these deazaflavoproteins share a TIM-barrel fold and are structurally related to FMN-dependent luciferases and monooxygenases. In this work, we traced the origin and evolutionary history of the F420-dependent enzymes within the luciferase-like superfamily. By a thorough phylogenetic analysis we inferred that the F420-dependent enzymes emerged from a FMN-dependent common ancestor. Furthermore, the data show that during evolution, the family of deazaflavoproteins split into two well-defined groups of enzymes: the F420-dependent dehydrogenases and the F420-dependent reductases. By such event, the dehydrogenases specialized in generating the reduced deazaflavin cofactor, while the reductases employ the reduced F420 for catalysis. Particularly, we focused on investigating the dehydrogenase subfamily and demonstrated that this group diversified into three types of dehydrogenases: the already known F420-dependent glucose-6-phosphate dehydrogenases, the F420-dependent alcohol dehydrogenases, and the sugar-6-phosphate dehydrogenases that were identified in this study. By reconstructing and experimentally characterizing ancestral and extant representatives of F420-dependent dehydrogenases, their biochemical properties were investigated and compared. We propose an evolutionary path for the emergence and diversification of the TIM-barrel fold F420-dependent dehydrogenases subfamily.
Assuntos
Archaea/enzimologia , Proteínas Arqueais/classificação , Bactérias/enzimologia , Proteínas de Bactérias/classificação , Evolução Molecular , Oxirredutases/classificação , Riboflavina/análogos & derivados , Proteínas Arqueais/química , Proteínas Arqueais/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Biocatálise , Escherichia coli/genética , Oxirredutases/química , Oxirredutases/genética , Filogenia , Riboflavina/química , Especificidade por SubstratoRESUMO
The research on the synthesis of steroids and its derivatives is of high interest due to their clinical applications. A particular focus is given to molecules bearing a D-ring lactone like testolactone because of its bioactivity. The Aspergillus genus has been used to perform steroid biotransformations since it offers a toolbox of redox enzymes. In this work, the use of growing cells of Aspergillus parasiticus to study the bioconversion of dehydro-epi-androsterone (DHEA) is described, emphasizing the metabolic steps leading to D-ring lactonization products. It was observed that A. parasiticus is not only capable of transforming bicyclo[3.2.0]hept-2-en-6-one, the standard Baeyer-Villiger monooxygenase (BVMO) substrate, but also yielded testololactone and the homo-lactone 3ß-hydroxy-17a-oxa-D-homoandrost-5-en-17-one from DHEA. Moreover, the biocatalyst degraded the lateral chain of cortisone by an oxidative route suggesting the action of a BVMO, thus providing enough metabolic evidences denoting the presence of BVMO activity in A. parasiticus. Furthermore, since excellent biotransformation rates were observed, A. parasiticus is a promising candidate for the production of bioactive lactone-based compounds of steroidal origin in larger scales.
