Part:BBa_K3039004

MHETase W397A

The enzymes PETase and MHETase were first discovered in Ideonella sakaiensis in 2016 by a group of researchers in Japan. These enzymes were found to degrade polyethylene terephthalate (PET) into its monomers, terephthalic acid (TPA) and ethylene glycol (EG). PETase degrades PET into Mono-(2-hydroxyethyl)terephthalic acid (MHET), Bis(2-Hydroxyethyl) terephthalate (BHET) and TPA, the main product being MHET. MHET is further degraded by MHETase into TPA and EG. We are aiming to use mutants of these enzymes to degrade the microfibres that are coming off clothing during washing cycles. The enzymes would be secreted into a filter that captures the microfibres. This sequence is the Escherichia coli K12 (E. coli K12) codon optimized DNA of the W397A mutant MHETase, with an attached His tag. The His tag was attached in order to more easily identify the enzymes. The wild type MHETase doesn’t show BHET degrading activity. This mutation has been reported in past papers to give MHETase the ability to degrade BHET.

The native predicted signal peptide (Met1-Ala19) was removed from the WT MHETase sequence (Palm et al 2019) and replaced with a start codon (Met), however all mutations are numbered according to the full-length WT sequence. The amino acid sequence was submitted to Twist Bioscience who codon optimised the sequence for E. coli, ensuring that there were no forbidden restriction sites, BsaI or SapI, to allow for potential TypeIIS assembly. The resulting CDS was synthesised and cloned, by Twist, into pET28. This added a 63 AA His-tag and thrombin cleavage site to the N-terminal of the protein, a T7 promoter and T7 terminator.

Western blot of the soluble fraction of Arctic Express strain showing expression of all mutants. The PageRuler Plus prestained protein ladder was used and labeled with the corresponding sizes. The negative control is labeled with 1. This part (MHETase W397A) is labeled with 6. A clear band is visible with a size of about 65 kDa which is the size of MHETase with the His tag attached to it.

Sequence and Features

Assembly Compatibility:

• 10
  INCOMPATIBLE WITH RFC[10]

  Illegal PstI site found at 260
  Illegal PstI site found at 1021
  
• 12
  INCOMPATIBLE WITH RFC[12]

  Illegal PstI site found at 260
  Illegal PstI site found at 1021
  
• 21
  COMPATIBLE WITH RFC[21]
• 23
  INCOMPATIBLE WITH RFC[23]

  Illegal PstI site found at 260
  Illegal PstI site found at 1021
  
• 25
  INCOMPATIBLE WITH RFC[25]

  Illegal PstI site found at 260
  Illegal PstI site found at 1021
  
• 1000
  COMPATIBLE WITH RFC[1000]