Analyzing the Unique Properties of PETase in Comparison to Other PET-Degrading Enzymes

Polyethylene Terephthalate (PET) is a common thermoplastic polymer used in the manufacturing of materials such as water bottles and polyester fibers. Since PET is so durable, it does not fully break down, causing major concerns for ocean ecosystems and landfills. In ocean ecosystems, PET is broken down into microplastics which are consumed by aquatic organisms, causing the death of these organisms due to endocrine disruption. In landfills, PET plastics accumulate for long periods of time without breaking down. In sludge samples in 2016 in Japan, however, an organism with PET-degrading abilities was discovered: Ideonella sakaiensis. This bacteria degrades PET through a novel enzyme known as PETase, the most efficient PET-degrading enzyme with the unique ability to convert PET into energy. We studied the amino acid sequence of PETase, in comparison to that of cutinase from Saccharomonospora viridis and polyester hydrolase from Pseudomonas aestusnigri, to find differences that would contribute to PETase’s unique properties. Using Clustal Omega’s sequencing software, we analyzed the sequences of these three enzymes at key sites: Subsite I, Subsite II, and the Catalytic Triad. Through comparing the amino acids and their properties at key locations, we found that PETase has unique amino acids at 238, 246, and 280, part of subsite II. We concluded that one of the main reasons for PETase’s unique catalytic capabilities is its unique amino acids at key points. These findings have clear applications for future research involving PETase, as it could be bioengineered to further maximize its efficiency at degrading PET plastics.