Surface staining of E. coli

From: Wallace Lauzon (wlauzon@uottawa.ca)
Date: Thu May 18 2000 - 15:46:27 EST


Hi,

I just did a quick and dirty preliminary experiment to look for the surface
expression of an inducible recombinant protein in E. coli and got a very
puzzling result.  I am staining with polyclonal antisera raised in rabbits
to the native form of the recombinant bacterial protein that I know works in
an ELISA.  The secondary is a commercial goat anti-rabbit IgG-PE.  I didn't
titrate the antibodies, so I expected a certain amount of background.

In the induced culture, I found that the entire population shifted nicely to
the right when the primary and secondary antibodies were present compared to
the autofluorescence tube.  However, the secondary antibody alone resulted
in 2 populations.  One, matching the autofluorescence peak and the other
(roughly 50% of the sample) staining significantly brighter than the
positive (primary + secondary).
In the uninduced culture, there was little staining in either the
primary+secondary tube or in the secondary alone tube.  Both the induced and
the uninduced came from the same culture which was split and incubated in
the presence or absence of arabinose for 4h.

I would appreciate any insight the you may have regarding these results.

Cheers,

Wallly

Wallace Lauzon, PhD
Dept. Biochemistry, Microbiology, and Immunology
Faculty of Medicine
University of Ottawa
451 Smyth Rd
Ottawa, Ontario
CANADA
K1H 8M5
Phone: (613) 562-5800 x8244
FAX: (613) 562-5452



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