Part:BBa_K4324100

NAD(P)H-dependent D-xylose reductase from S. stipitis

This part is the CDS of the XYL1 gene from S. stipitis that induces xylose reductase, and has been codon-optimised for expression in E. coli.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  INCOMPATIBLE WITH RFC[1000]

  Illegal SapI.rc site found at 747
  

Usage and Biology

Our project focused on the improvement of xylose utilisation in E. coli. One part of this process was to incorporate a yeast-derived XR-XDH pathway

Figure 1 Xylose metabolism pathways of various microorganisms, from Biochemical routes for uptake and conversion of xylose by microorganisms by Zhao, Z., Xian, M., Liu, M. et al.

Xylose reductase (EC 1.1.1.307), also known as aldose reductase, is an enzyme that serves as a catalyst for the conversion of xylose into xylitol, and vice versa, according to the following chemical equation:

D-xylose + NAD(P)H + H⁺ ⇌ xylitol + NAD(P)⁺

In S. stipitis yeast cells, XR forms the first process in the XR-XDH pathway, which converts xylose into xylulose via xylitol. Xylulose is then converted into xylulose-5-phosphate (X5P) for further metabolism in the pentose phosphate pathway.

E. coli do not exhibit the XR-XDH pathway, instead having an XI pathway that directly converts xylose into xylulose. Hence, together with xylitol dehydrogenase (XDH) which can convert xylitol to xylulose, XR presents an alternate xylose metabolism pathway for E. coli.

Furthermore, as the reaction from xylose to xylitol is reversible, xylose reductase enables E. coli to utilise xylitol as an energy source through its conversion to xylose, which then follows the XI pathway.

References

1. https://www.uniprot.org/uniprotkb/P31867/entry
2. https://biotechnologyforbiofuels.biomedcentral.com/articles/10.1186/s13068-020-1662-x 3. https://pubmed.ncbi.nlm.nih.gov/3921014/