Designed by: Perry Tsai   Group: iGEM2006_Harvard   (2006-10-30)

Lac-inducible generator of Lpp-OmpA(46-66)-Streptavidin wild-type + His6tag

This device contains a lac promoter and strong ribosome binding site for lac-inducible expression of the fusion protein of Lpp signal peptide, OmpA aa46-66, and streptavidin wild-type + His6 tag. This expression should display streptavidin on the cell surface of E. coli.

NOTE ABOUT THE SEQUENCE: The mixed site between parts is 'only' six base pairs, ACTAGA. There is no spacer T or G nucleotide. These spacer nucleotides have been placed in the results for "get selected sequence" as an automatic composite-parts addition for the BioBricks mixed site between assembled parts. However, this does not apply for the two spacer nucleotides betweeon R0010 and B0034, and the one spacer nucleotide after B0034, because those were standard BioBricks.

Possible error in Spring 2008 distribution information

The sequence data for this construct in the 2008 Spring Distribution suggest it's on plasmid backbone pSB1A3, not pSB1A2 as the stated in the documentation. The bases following the PstI site are 5'-tccggcaaaaaa-3' which matches pSB1A3, while the same locus on pSB1A2 reads 5'-gcttcctcgctc-3'.

Also, the 'inconsistent' sequence data is due to the fact that, in order to conform to the composite parts format, an 8 base scar is shown in the 'get selected sequence' readout. The sequencing data is checked against this sequence with the 8-base scars, not the 6-base in-frame scars that are part of the sequencing data from the actual plasmid. --robere, University of Washington iGEM team, 11 Sept 2009

Usage and Biology

Characterized by [ Washington 2009 iGEM team]. We sought to use these parts to display streptavidin on the surface of the cell. We confirmed the expression of these proteins by Western blot using an anti-His detection reagent. We then assayed each part for biotin binding using flow cytometry. Our assay was to incubate cells with a biotinylated fluorophore, wash cells, and then monitor by flow cytometry the retention of fluorophore on the surface of cells that had this part induced with IPTG. In this experiment, increased florescence would indicate binding interactions between the streptavadin and the biotin. Our results are described below in the histogram, the y-axis is the event frequency (equivalent to the number of cells counted) and the x-axis is the fluorescence intensity (FL1-A: 488 nm excitation, 515-545 nm emission) of the cells/beads:

We also visualized the part-expressing cells using a fluorescence microscope after incubation with biotinylated fluorophore (as for the flow cytometry experiment described above). We used the same streptavidin-coated beads (SVP-15-5 1.5-1.9 μm polystyrene spheres, [ Spherotech]) as a positive control for streptavidin-biotin binding. In this experiment we sought to visualize binding between the cells and the biotinylated flourophore. The results are summarized below.

Sequence and Features

Assembly Compatibility:
  • 10
  • 12
  • 21
    Illegal BamHI site found at 432
  • 23
  • 25
    Illegal AgeI site found at 474
    Illegal AgeI site found at 525
  • 1000