Part:BBa_K2924020

Promoter AR with the chromoprotein amilCP

Long-chain fatty acid sensitive promoter PAR expressing amilCP. This part was used to characterize amilCP.

Usage and Biology

This year the iGEM team from Düsseldorf 2019 was working on the characterization of amilCP, a blue chromoprotein from the Acropora millepora (BBa_K592009) for the use as a reporter gene for a biosensor. For the characterization the synthetic P_AR from a previous publication ¹ was used and so the biosensor is sensitive for long chain fatty acids (LCFA). The plan was to implement a chromoprotein as a reporter gene, thus enabling to every laboratory to measure a biosensor without fluorescence applications - in contrast, most laboratories have access to a photometer. The chromoprotein amilCP can be observed with the naked eye, in addition to the measurement method by absorption at the wavelength 588 nm for example with a plate reader. Therefore, this option is available for everyone. 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
  COMPATIBLE WITH RFC[1000]

Characterization

Fig.1: Promoter AR with reporter gene amilCP in a pBb backbone. The backbone has a chloramphenicol resistance and a medium copy ori p15A. EcoRI and XbaI were used as restriction enzymes.

Chromoproteins are a good alternative to fluorescent proteins like red fluorescent protein (RFP). The amilCP protein has an absorption maximum at 588 nm and the blue color can be seen with naked eye. Chromoproteins have the benefit that they can measured by absorption and thus can be used in every laboratory.

Fig.2: Response of P_AR+amilCP (blue) to different chain lengths of fatty acids compared to an empty vector control (gray). Plot A presents the response for lauric acid, plot B for myristic acid, plot C for palmitic acid and plot D for stearic acid.

The experiments with the blue chromoprotein amilCP showed that the production of the chromoprotein is increased by a higher concentration of fatty acids in the medium. The best result was achieved with the fatty acid stearic acid. The biosensor also worked for the chain lengths from C14:0 and C16:0. The EVC is in thus experiments lower than the samples with amilCP. By adding lauric acid (C12:0) to the culture medium the production of amilCP increased, but the EVC also increased a lot and is close to amilCP, so it is not certain if this result can be used for an nearly distinct conclusion.

References

1: Fuzhong Zhang, James M Carothers, Jay D Keasling. “Design of a dynamic sensor-regulator system for production of chemicals and fuels derived from fatty acids” Nature Biotechnology volume 30, pages 354–359 (2012)