In silico approach for identification of polyethylene terephthalate hydrolase (PETase)-like enzymes

Abstract

Substantial use of plastics as packaging material has become a global concern due to their limited recycling or incineration options and requires periodic degradation to avoid accumulation as a pollutant in the environment. Several chemical and physical properties such as surface area, hydrophobicity, chemical structure, molecular weight, melting temperature, crystallinity, and so on influence their biodegradation. Previously, hydrolases from Thermobifida fusca were reported to have higher degradability until Polyethylene terephthalate hydrolase (PETase) from Ideonella sakaiensis was discovered that showed better specificity for PET. The catalytic triad contains Ser160, Asp206 and His237 along with conserved serine hydrolase motif “Gly-X1-Ser-X2-Gly” having tryptophan at X1 for extending the hydrophobic surface of the active site and cysteine in the vicinity providing thermal stability via additional disulfide bonds. Here, we employed in silico screening techniques for the identification of potential plastic degrading PETases, initiating with sequence similarity search using IsPETase, scrutinizing for the presence of the conserved serine hydrolase motif containing tryptophan at X1 position and cysteine in the vicinity. Five PETases belonging to the diene-lactone hydrolase protein family from different bacterial species were identified in the initial screening, which was further confirmed by molecular docking studies indicating their capacity to bind MHET as substrate for degradation. Our study provides a reliable framework for identification and characterization of PETases involved in biodegradation of plastics which can be further explored for improving their efficiency and suitability under different conditions. This is extremely beneficial approach considering that the increasing demand for microbial enzymes due to the continued accumulation of plastics in the environment.