Part:BBa_K4033001

ZhuI

ZhuI is a monodomain ARO/CYC that promotes the regiospecific C7–C12 first-ring cyclization for unreduced polyketide chains of variable lengths (C16 and C18–C20). And C7–C12 specificity for first-ring cyclization is unique among nonreducing type II PKS systems.

Biology and Usage

ZhuI encodes the cyclases that catalyzes formation of the C7-C12 first ring closure, which is unique among nonreducing type II PKS systems. ZhuI is proposed to catalyze aldol condensation between C7 and C12 (followed by aromatization) to yield intermediate SEK4b, which is then transferred to ZhuJ for second-ring cyclization between C5 and C14 (followed by aromatization) to give intermediate SEK4. After third-ring cyclization between C2 and C15, presumed to occur spontaneously, flavokermesic acid anthrone forms（Fig.1）[2].

ZhuI and ZhuJ are usually used together for typeⅡPKS reconstitution.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  INCOMPATIBLE WITH RFC[12]

  Illegal NheI site found at 229
  
• 21
  INCOMPATIBLE WITH RFC[21]

  Illegal XhoI site found at 203
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]

Experimental approach

References

[1] Ames, B. D., Lee, M. Y., Moody, C., Zhang, W., Tang, Y., & Tsai, S. C. (2011). Structural and biochemical characterization of ZhuI aromatase/cyclase from the R1128 polyketide pathway. Biochemistry, 50(39), 8392–8406. https://doi.org/10.1021/bi200593m [2] Frandsen, R.J.N., Khorsand-Jamal, P., Kongstad, K.T. et al. Heterologous production of the widely used natural food colorant carminic acid in Aspergillus nidulans. Sci Rep 8, 12853 (2018). https://doi.org/10.1038/s41598-018-30816-9