Julius B. Lucks/Bibliography/Ham-BiotechBioengineering-94-2006

Notes on [1]

• fim inversion in E. coli - unidirectional switch
• expression system - arabinose inducible fimE, and fim invertible DNA segment containing constitutively active promoter
  1. target gene has promoter in OFF orientation (no transcribed product)
  2. add arabinose, fimE flips DNA sequence, turning promoter in ON position causing transcription of target gene
  • tightly controlled basal expression, highly inducible
    • large scale expression of toxic proteins
• Other inducible systems
  • IPTG induced trc (P_trc)
  • arabinose induced araBAD (P_BAD)
• Podhajska 1985 - inversion-based expression system using lambda Int and attP/attB [2]
  • tight control when not intuced, and high induction level when induced - (Sektas, 2001)
  • requires heat-shock induction mechanism
• type I fimbrae in E. coli has phase variation
  • due to inversion of 314-bp segment containing promoter of fimA by invertases FimB and FimE (Klemm, 1986)
    • FimB inverts both directions, FimE inverts preferrentially ON to OFF
  • invertases bind to non-identical inverted repeats surrounding invertible DNA segment
• 'sequences between promoter and RBS could form mRNA secondary structures that could aversly affect expression' - (de Smit and van Duin 1994, Pfleger 2005)
• arabinose induces once to start gene expression - no need for extra inducer - can use a pulse of arabinose

• flipase memory system
• diagram attP/B push system

References

1. Ham TS, Lee SK, Keasling JD, and Arkin AP. A tightly regulated inducible expression system utilizing the fim inversion recombination switch. Biotechnol Bioeng. 2006 May 5;94(1):1-4. DOI:10.1002/bit.20916 |

   Notes

2. Podhajska AJ, Hasan N, and Szybalski W. Control of cloned gene expression by promoter inversion in vivo: construction of the heat-pulse-activated att-nutL-p-att-N module. Gene. 1985;40(1):163-8. DOI:10.1016/0378-1119(85)90038-1 |

   Notes