User:Hfleming2017/PETase

Old

Mutations

In 2018 scientists from the University of Portsmouth with the collaboration of the National Renewable Energy Laboratory of the United States Department of Energy developed a mutant of this PETase that degrades PET faster than the one in its natural state. In this study it was also shown that PETases can degrade polyethylene 2,5-furandicarboxylate (PEF).

Studies have demonstrated that the β1-β2 connecting loop located far from the active site of PETase of I. sakaiensis (IsPETase)structure is very flexible it is suggested that it can be considered for mutagenesis to increase the thermal stability of IsPETase.

New:

The discovery of PETase from I. sakaiensis provides a potential solution to the world’s amassing plastic; however, naturally occurring enzymes are limited in their degradation abilities due to instability, low activity, and expression levels, which ultimately drive the need for improvement if they are to be used for large-scale industrial applications. One strategy implemented site-directed mutagenesis to create a variant, IsPETaseR280A, which increased the activity of PETase by replacing the arginine with alanine in position 280. This change resulted in a 22.4% increase in activity. Similarly, a double mutant, S238F/W159H, constricted the PETase active site and was 4.13% more active than the wildtype. It was also discovered that this same mutant can degrade polyethylene 2,5-furandicarboxylate (PEF). Comparatively, at position 121, serine was swapped for either aspartic acid or glutamic acid, while at position 186, aspartate was exchanged for histidine, creating S121D/D186H and S121E/D186H mutants, which created extra hydrogen bonds that improved the stability of PETase. Other successful approaches to improving PETase stability included adding Ca2+ or Mg2+, disulfide bonds and salt bridges as well as glycosylation. Another double mutant, W159H/F229Y, displayed an increased thermal stability in comparison to the wild type ; however, the β1-β2 connecting loop of the enzyme may also be a future target for mutagenesis due to its flexibility and distance from the active site.