Device

Part:BBa_K533010:Design

Designed by: ZHANG Yunxiao   Group: iGEM11_Tsinghua   (2011-09-29)
Revision as of 09:19, 5 October 2011 by Wishyx (Talk | contribs) (→‎Design Notes)

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PAA receptor weakened expression cassette


Assembly Compatibility:
  • 10
    COMPATIBLE WITH RFC[10]
  • 12
    COMPATIBLE WITH RFC[12]
  • 21
    COMPATIBLE WITH RFC[21]
  • 23
    COMPATIBLE WITH RFC[23]
  • 25
    INCOMPATIBLE WITH RFC[25]
    Illegal AgeI site found at 1936
  • 1000
    INCOMPATIBLE WITH RFC[1000]
    Illegal BsaI site found at 2514
    Illegal BsaI site found at 3582


Design Notes

When a E. coli strain lack all the chemoreceptors express a certain receptor in the plasmid, it will be conferred the chemotaxis towards the ligand. Interestingly, sensitivity of chemotaxis does not increase as the expression level of the receptor increases; on the contrary, low expression level of the receptor is essential to sensitive chemotaxis. It can be inferred that high level of receptors caused an internal noise, which interfered with normal chemotaxis.

This sequence was cloned from plasmid PD12-TarPA4 (kind gift from Prof. Mark Goulian, U Penn). An accidental ligation occured, causing the receptor coding sequence to insert into lacI sequence. Furthermore,some of the sequence in lacI can serve as a weak promoter, driving extremely low level expression of the receptor.

This receptor is specific for phenylacetic acid, or PAA for short. As the experiments in Goulian's lab demonstrated, the maximum concentration of the chemoattractant is 10mM. A concentration higher than that will saturate the receptor and hinder chemotaxis.

Source

Gift from Dr. Goulian

References