MOLECULAR DOCKING STUDY BETWEEN LACCASES OF THE ISOLATE Phlebia brevispora BAFC633 WITH AGROCHEMICALS OF SANITARY INTEREST

AYALA SCHIMPF AR; GAMARRA, M;; FONSECA MI; ZAPATA PD

Congreso; XVII Congreso Argentino de Microbiología General; 2022

Chlorpyrifos and 2,4D-dichlorophenoxyacetic acid (2,4D) are widely used pesticides in Misionesagriculture. Its intensive use generates pollution of ecosystems and the intoxication of living beingssuch as man, which is why its monitoring in the environment is essential. In this sense, the fungusPhlebia brevispora BAFC633 isolated in Misiones is characterized by the degradation of highlyrecalcitrant compounds, a condition given by the constituent enzymatic systems in which laccases playa predominant role given their unspecificity of substrate possible to be oxidized. The objective of thework was to model two laccases (LacI and PhlacII) belonging to P. brevispora BAFC633 and to evaluatetheir molecular coupling with the pesticides of interest for subsequent structural modifications thatenable their future use in the development of an enzymatic sensor for environmental monitoring ofthese contaminants. The laccase genes LacI and PhlacII (GenBank Acc.No. AFK30375.2 and Q01679.2respectively) were obtained by mapping to the reference from the genome published in JGIMycoCosm (https://genome.jgi.doe.gov/portal/Phlbr1/Phlbr1. download.html). Homology modelingwas performed using Phyre2, with the Trametes versicolor laccase (PDBID: 1GYC) as template.Subsequently, the models were contrasted with the structure of a Bacillus subtilis laccase cocrystallized with ABTS (PDBID: 3ZDW). The 2D structures of the pesticides were obtained usingPubChem and their preparation as ligands was carried out with Avogadro. The laccase receptors wereoptimized with Chimera, and the molecular coupling was performed with AutoDock 4.2 usingLamarckian Genetic Algorithm (LGA) with 100 runs for each of the couplings. The surface comparisonbetween the co-crystallized structure and the laccase-ABTS complexes showed a clear differencebetween the pockets. The divergence between the atomic distances of the model structure and 3ZDWgenerated a distinct laccase surface topology pattern; LacI obtained the best RMSD value (5.540 Å)and a binding energy of -9.41 kcal mol-1, while PhLacII obtained an RMSD of 5.988 Å and a bindingenergy of -8.41 kcal mol-1. The catalytic site of PhLacII presented a hydrophobic region within thepocket very close to the T1 site, indicating a strong interaction with a hydrophobic or aromatic groupof the ligand. LacI presented extra acceptor sites, showing a polar environment capable of stabilizingthe binding of polar groups. Both proteins revealed the presence of a characteristic aromatic site atthe opening of the pocket. Chlorpyrifos presented better coupling with PhLacII (-7.87 kcal mol-1) in39% of the conformations obtained, while for 2,4D it was LacI (-5.06 kcal mol-1) with 98% of theconformations obtained in the docking. The analysis of the results obtained in the interactions willallow us to postulate mutations in the structures of the laccases under study, in order to increase theirability to bind to substrates.